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Marijuana Can Increase a Teenager’s Risk of Psychosis
Probing Psychopathic Brains
Source: Probing Psychopathic Brains
Probing Psychopathic Brains
Probing Psychopathic Brains
Josh Buckholtz wants to change the way you think about psychopaths — and he’s willing to go to prison to do it.
An Associate Professor of Psychology, Buckholtz is the senior author of a study that relies on brain scans of nearly 50 prison inmates to help explain why psychopaths make poor decisions that often lead to violence or other anti-social behavior.
What they found, he said, is psychopath’s brains are wired in a way that leads them to over-value immediate rewards and neglect the future consequences of potentially dangerous or immoral actions. The study is described in a July 5 paper in Neuron.
“For years, we have been focused on the idea that psychopaths are people who cannot generate emotion and that’s why they do all these terrible things,” Buckholtz said. “But what what we care about with psychopaths is not the feelings they have or don’t have, it’s the choices they make. Psychopaths commit an astonishing amount of crime, and this crime is both devastating to victims and astronomically costly to society as a whole.
“And even though psychopaths are often portrayed as cold-blooded, almost alien predators, we have been showing that their emotional deficits may not actually be the primary driver of these bad choices. Because it’s the choices of psychopaths that cause so much trouble, we’ve been trying to understand what goes on in their brains when the make decisions that involve trade-offs between the costs and benefits of action.,” he continued. “In this most recent paper…we are able to look at brain-based measures of reward and value and the communication between different brain regions that are involved in decision making.”
Obtaining the scans used in the study, however, was no easy feat — where most studies face an uphill battle in bringing subjects into the lab, Buckholtz’s challenge was in bringing the scanner to his subjects.
The solution came in form of a “mobile” scanner — typically used for cancer screenings in rural areas — that came packed in the trailer of a tractor trailer. After trucking the equipment to a two medium-security prisons in Wisconsin, the team — which included collaborators at the University of Wisconin-Madison and University of New Mexico — would spend days calibrating the scanner, and then work to scan as many volunteers as possible as quickly as possible.
“It was a huge undertaking,” he said. “Most MRI scanners, they’re not going anywhere, but in this case, we’re driving this inside a prison and then in very quick succession we have to assess and scan the inmates.”
The team ultimately scanned the brains of 49 inmates over two hours as they took part in a type of delayed gratification test which asked them to choose between two options — receive a smaller amount of money immediately, or a larger amount at a later time. The results of those tests were then fit to a model that allowed researchers to create a measure of not only how impulsive each participant’s behavior was, but to identify brain regions that play a role in assessing the relative value of such choices.
What they found, Buckholtz said, was people who scored high for psychopathy showed greater activity in a region called the ventral striatum — known to be involved in evaluating the subjective reward — for the more immediate choice.
“So the more psychopathic a person is, the greater the magnitude of that striatal response,” Buckholtz said. “That suggests that the way they are calculating the value rewards is dysregulated — they may over-represent the value of immediate reward.”
When Buckholtz and colleagues began mapping which brain regions are connected to the ventral striatum, it became clear why.
“We mapped the connections between the ventral striatum and other regions known to be involved in decision-making, specifically regions of the prefrontal cortex known to regulate striatal response,” he said. “When we did that, we found that connections between the striatum and the ventral medial prefrontal cortex were much weaker in people with psychopathy.”
That lack of connection is important, Buckholtz said, because this portion of the prefrontal cortex role is thought to be important for ‘mental time-travel’ — envisioning the future consequences of actions. There is increasing evidence that prefrontal cortex uses the outcome of this process to change how strongly the striatum responds to rewards. With that prefrontal modulating influence weakened, the value of the more immediate choice may become dramatically over-represented.
“The striatum assigns values to different actions without much temporal context” he said. “We need the prefrontal cortex to make prospective judgements how an action will affect us in the future — if I do this, then this bad thing will happen. The way we think of it is if you break that connection in anyone, they’re going to start making bad choices because they won’t have the information that would otherwise guide their decision-making to more adaptive ends.”
The effect was so pronounced, Buckholtz said, that researchers were able to use the degree of connection between the striatum and the prefrontal cortex to accurately predict how many times inmates had been convicted of crimes.
Ultimately, Buckholtz said, his goal is to erase the popular image of psychopaths as incomprehensible, cold-blooded monsters and see them for what they are — everyday humans whose brains are simply wired differently.
“They’re not aliens, they’re people who make bad decisions,” he said. “The same kind of short-sighted, impulsive decision-making that we see in psychopathic individuals has also been noted in compulsive over-eaters and substance abusers. If we can put this back into the domain of rigorous scientific analysis, we can see psychopaths aren’t inhuman, they’re exactly what you would expect from humans who have this particular kind of brain wiring dysfunction.”
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Source: Harvard
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Abstract for “Disrupted Prefrontal Regulation of Striatal Subjective Value Signals in Psychopathy” by Jay G. Hosking, Erik K. Kastman, Hayley M. Dorfman, Gregory R. Samanez-Larkin, Arielle Baskin-Sommers, Kent A. Kiehl, Joseph P. Newman, and Joshua W. Buckholtz in Neuron. Published online July 5 2017 doi:10.1016/j.neuron.2017.06.030
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Harvard “Probing Psychopathic Brains.” NeuroscienceNews. NeuroscienceNews, 5 July 2017.
<http://neurosciencenews.com/psychopathic-brains-7033/>.
<http://neurosciencenews.com/psychopathic-brains-7033/>.
Abstract
Disrupted Prefrontal Regulation of Striatal Subjective Value Signals in Psychopathy
Highlights
•Ventral striatal subjective value signals are amplified in incarcerated psychopaths
•Medial cortico-striatal intrinsic connectivity is weak in psychopathic individuals
•Cortico-striatal regulation of striatal activation is disrupted in psychopathy
•Diminished cortico-striatal regulation is associated with more criminal convictions
Summary
Psychopathy is a personality disorder with strong links to criminal behavior. While research on psychopathy has focused largely on socio-affective dysfunction, recent data suggest that aberrant decision making may also play an important role. Yet, the circuit-level mechanisms underlying maladaptive decision making in psychopathy remain unclear. Here, we used a multi-modality functional imaging approach to identify these mechanisms in a population of adult male incarcerated offenders. Psychopathy was associated with stronger subjective value-related activity within the nucleus accumbens (NAcc) during inter-temporal choice and with weaker intrinsic functional connectivity between NAcc and ventromedial prefrontal cortex (vmPFC). NAcc-vmPFC connectivity strength was negatively correlated with NAcc subjective value-related activity; however, this putative regulatory pattern was abolished as psychopathy severity increased. Finally, weaker cortico-striatal regulation predicted more frequent criminal convictions. These data suggest that cortico-striatal circuit dysregulation drives maladaptive decision making in psychopathy, supporting the notion that reward system dysfunction comprises an important neurobiological risk factor.
“Disrupted Prefrontal Regulation of Striatal Subjective Value Signals in Psychopathy” by Jay G. Hosking, Erik K. Kastman, Hayley M. Dorfman, Gregory R. Samanez-Larkin, Arielle Baskin-Sommers, Kent A. Kiehl, Joseph P. Newman, and Joshua W. Buckholtz in Neuron. Published online July 5 2017 doi:10.1016/j.neuron.2017.06.030
Marijuana Can Increase a Teenager’s Risk of Psychosis
Source: University of Montreal.
An UdeM study confirms the link between marijuana use and psychotic-like experiences in a Canadian adolescent cohort.
Going from an occasional user of marijuana to a weekly or daily user increases an adolescent’s risk of having recurrent psychotic-like experiences by 159%, according to a new Canadian study published today in the Journal of Child Psychology and Psychiatry. The study also reports effects of marijuana use on cognitive development and shows that the link between marijuana use and psychotic-like experiences is best explained by emerging symptoms of depression.
“To clearly understand the impact of these results, it is essential to first define what psychotic-like experiences are: namely, experiences of perceptual aberration, ideas with unusual content and feelings of persecution,” said the study’s lead author, Josiane Bourque, a doctoral student at Université de Montréal’s Department of Psychiatry. “Although they may be infrequent and thus not problematic for the adolescent, when these experiences are reported continuously, year after year, then there’s an increased risk of a first psychotic episode or another psychiatric condition.”
She added: “Our findings confirm that becoming a more regular marijuana user during adolescence is, indeed, associated with a risk of psychotic symptoms. This is a major public-health concern for Canada.”
What are the underlying mechanisms?
One of the study’s objectives was to better understand the mechanisms by which marijuana use is associated with psychotic-like experiences. Bourque and her supervisor, Dr. Patricia Conrod at Sainte Justine University Hospital Research Center hypothesized that impairments in cognitive development due to marijuana misuse might in turn exacerbate psychotic-like experiences.
This hypothesis was only partially confirmed, however. Among the different cognitive abilities evaluated, the development of inhibitory control was the only cognitive function negatively affected by an increase in marijuana use. Inhibitory control is the capacity to withhold or inhibit automatic behaviours in favor of a more contextually appropriate behaviour. Dr. Conrod’s team has shown that this specific cognitive function is associated with risk for other forms of substance abuse and addiction.
“Our results show that while marijuana use is associated with a number of cognitive and mental health symptoms, only an increase in symptoms of depression – such as negative thoughts and low mood – could explain the relationship between marijuana use and increasing psychotic-like experiences in youth,” Bourque said.
What’s next?
These findings have important clinical implications for prevention programs in youth who report having persistent psychotic-like experiences. “While preventing adolescent marijuana use should be the aim of all drug strategies, targeted prevention approaches are particularly needed to delay and prevent marijuana use in young people at risk of psychosis,” said Patricia Conrod, the study’s senior author and a professor at UdeM’s Department of Psychiatry.
Conrod is optimistic about one thing, however: the school-based prevention program that she developed, Preventure, has proven effective in reducing adolescent marijuana use by an overall 33%. “In future programs, it will be important to investigate whether this program and other similar targeted prevention programs can delay or prevent marijuana use in youth who suffer from psychotic-like experiences,” she said. “While the approach seems promising, we have yet to demonstrate that drug prevention can prevent some cases of psychosis.”
A large youth cohort from Montreal
The study’s results are based on the CIHR-funded Co-Venture project, a cohort of approximately 4,000 adolescents aged 13 years old from 31 high schools in the Greater Montreal area. These teens are followed annually from Grade 7 to Grade 11. Every year they fill out computerized questionnaires to assess substance use and psychiatric symptoms. The teens also complete cognitive tasks to allow the researchers to evaluate their IQ, working memory and long-term memory as well as their inhibitory control skills.
To do their study, the research team first confirmed results from both the United Kingdom and Netherlands showing the presence of a small group of individuals (in Montreal, 8%) among the general population of adolescents who report recurrent psychotic-like experiences. Second, the researchers explored how marijuana use between 13 and 16 years of age increases the likelihood of belonging to the 8%. Finally, they examined whether the relationship between increasing use of marijuana and increasing psychotic-like experiences can be explained by emerging symptoms of anxiety or depression, or by the effects of substance use on developing cognitive abilities.
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Funding: This study was funded by a Canadian Institutes of Health Research (CIHR) doctoral fellowship to Josiane Bourque, a Fond de recherche du Québec – Santé senior investigator award to Patricia Conrod, and a CIHR grant to Patricia Conrod and co-investigators.
Source: Mélanie Dallaire – University of Montreal
Image Source: NeuroscienceNews.com image is adapted from the UM news release.
Original Research: Abstract for “Cannabis use and psychotic-like experiences trajectories during early adolescence : the coevolution and potential mediators,” by Josiane Bourque, Mohammad H. Afzali, Maeve O’Leary-Barrett and Patricia Conrod in Journal of Child Psychology and Psychiatry. Published online July 5 2017 doi:10.1111/jcpp.12765
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University of Montreal “Marijuana Can Increase a Teenager’s Risk of Psychosis.” NeuroscienceNews. NeuroscienceNews, 5 July 2017.
<http://neurosciencenews.com/psychosis-teen-marijuana-7034/>.
<http://neurosciencenews.com/psychosis-teen-marijuana-7034/>.
Abstract
Cannabis use and psychotic-like experiences trajectories during early adolescence : the coevolution and potential mediators,
Background
The authors sought to model the different trajectories of psychotic-like experiences (PLE) during adolescence and to examine whether the longitudinal relationship between cannabis use and PLE is mediated by changes in cognitive development and/or change in anxiety or depression symptoms.
Methods
A total of 2,566 youths were assessed every year for 4-years (from 13- to 16-years of age) on clinical, substance use and cognitive development outcomes. Latent class growth models identified three trajectories of PLE: low decreasing (83.9%), high decreasing (7.9%), and moderate increasing class (8.2%). We conducted logistic regressions to investigate whether baseline levels and growth in cannabis use were associated with PLE trajectory membership. Then, we examined the effects of potential mediators (growth in cognition and anxiety/depression) on the relationship between growth in cannabis use and PLE trajectory.
Results
A steeper growth in cannabis use from 13- to 16-years was associated with a higher likelihood of being assigned to the moderate increasing trajectory of PLE [odds ratio, 2.59; 95% confidence interval (CI), 1.11–6.03], when controlling for cumulative cigarette use. Growth in depression symptoms, not anxiety or change in cognitive functioning, mediated the relationship between growth in cannabis use and the PLE moderate increasing group (indirect effect: 0.07; 95% CI, 0.03–0.11).
Conclusions
Depression symptoms partially mediated the longitudinal link between cannabis use and PLE in adolescents, suggesting that there may be a preventative effect to be gained from targeting depression symptoms, in addition to attempting to prevent cannabis use in youth presenting increasing psychotic experiences.
“Cannabis use and psychotic-like experiences trajectories during early adolescence : the coevolution and potential mediators,” by Josiane Bourque, Mohammad H. Afzali, Maeve O’Leary-Barrett and Patricia Conrod in Journal of Child Psychology and Psychiatry. Published online July 5 2017 doi:10.1111/jcpp.12765
Depression Affects Male and Female Brains Differently
Your Hands May Reveal the Struggle to Maintain Self Control
Brain Stimulation May Help Children With Learning Difficulties
Brain Stimulation May Help Children With Learning Difficulties
Summary: An exploratory study reveals a brain stimulation method previously suggested to help adults learn math may also help children with mathematical learning difficulties.
Source: Oxford University.
Applying a brain stimulation method, which was previously suggested to enhance mathematical learning in healthy adults, may improve the performance of children with mathematical learning difficulties, according to an exploratory study by researchers from the universities of Oxford and Cambridge.
The early stage, small-scale study, which has been published in Nature’s open access journal Scientific Reports, involved twelve children between the ages of eight and eleven with learning difficulties in mathematics.
The study took place at Fairley House, a specialist day school for children with specific learning difficulties in London. After careful safety screening, the children were split into two groups of six. One group wore a cap attached to a light, battery-operated device through which painless low electrical current was applied over the left and right areas on the forehead, above regions of the brain called the dorsolateral prefrontal cortices. This region has been highlighted to play a role in mathematical learning.
The method of stimulation, which is known as transcranial random noise stimulation (tRNS), was applied in nine 20-minute sessions over five weeks.
The other group wore an identical cap but did not receive any stimulation. Children did not detect reliably whether they received stimulation or not.
While wearing the caps, the children in both groups played a specially-designed numerical training game developed by the researchers, which integrates numerical learning and visuospatial components, with bodily movements, while the game changed its level adaptively based on the child’s performance.
Immediately before and after the trial, the researchers also measured their performance in a mathematical test called MALT, a standardized diagnostic tool calibrated to the UK’s national curriculum.
They found that stimulation yields a mixed effect in term of performance but improved the learning of children during the numerical training game, compared to those who wore the ‘placebo’ cap.
The results also hinted that the positive effects of tRNS have contributed to improved results on the MALT test.
These findings resemble previous studies on healthy adults that suggested tRNS over the same regions of the brain improved arithmetic learning compared to the control group, and generalised to related materials that were not specifically trained.
Professor Roi Cohen Kadosh of Oxford University’s Department of Experimental Psychology, said: ‘Compared to children without learning difficulties, children with learning difficulties have a brain that works differently. This is usually associated with poor learning, and in turn might impair typical brain development.
‘Learning difficulties are usually treated by behavioural interventions, but these have shown little efficacy, especially in brains with neural atypicalities. Our research suggests that children with learning difficulties might benefit from combining their learning with tRNS, which has been suggested to improve learning and alter brain functions in healthy adults.’
But the authors warn that this study is just the first step from a scientific perspective. To understand the potential of tRNS for improving learning and cognition of children with learning difficulties, we need to run more studies, and see whether these results replicate. We also need to understand the neural mechanisms that support such improvements in learning.
‘Maths is something that many people find challenging, and worries a lot of people so the potential for neuroscience to help those with difficulties to learn better is exciting but there are still a lot of ethical and scientific issues to explore,’ says Professor Cohen Kadosh who also worked with Oxford neuroethicists to deal with such problems.
‘It is also important to explore its impact on children from different educational and cultural backgrounds, and children with other developmental conditions, such as dyslexia or ADHD. This would allow a better understanding if such approach could be used in schools to help those with learning difficulties in the future.’
This type of study was first to take place in a school environment. Professor Cohen Kadosh said he hopes this trial will encourage other schools to take part in future neuroscientific research, but warned that members of the public should not try to use tRNS on themselves or on children.
‘The trial was carried out by experts with years of training in brain stimulation and expertise in mathematical cognition, who did careful medical and safety screening before deciding if a child could take part in the study,’ he said.
‘We urge people not to buy devices claimed to achieve these or similar results – do not try this at home!’
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Source: Oxford University
Image Source: NeuroscienceNews.com image is adapted from the Oxford University news release.
Original Research: Full open access research for “Transcranial random noise stimulation and cognitive training to improve learning and cognition of the atypically developing brain: A pilot study” by Chung Yen Looi, Jenny Lim, Francesco Sella, Simon Lolliot, Mihaela Duta, Alexander Alexandrovich Avramenko & Roi Cohen Kadosh in Scientific Reports. Published online July 5 2017 doi:10.1038/s41598-017-04649-x
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Oxford University “Brain Stimulation May Help Children With Learning Difficulties.” NeuroscienceNews. NeuroscienceNews, 6 July 2017.
<http://neurosciencenews.com/math-learning-brain-stimulations-7042/>.
<http://neurosciencenews.com/math-learning-brain-stimulations-7042/>.
Abstract
Transcranial random noise stimulation and cognitive training to improve learning and cognition of the atypically developing brain: A pilot study
Learning disabilities that affect about 10% of human population are linked to atypical neurodevelopment, but predominantly treated by behavioural interventions. Behavioural interventions alone have shown little efficacy, indicating limited success in modulating neuroplasticity, especially in brains with neural atypicalities. Even in healthy adults, weeks of cognitive training alone led to inconsistent generalisable training gains, or “transfer effects” to non-trained materials. Meanwhile, transcranial random noise stimulation (tRNS), a painless and more direct neuromodulation method was shown to further promote cognitive training and transfer effects in healthy adults without harmful effects. It is unknown whether tRNS on the atypically developing brain might promote greater learning and transfer outcomes than training alone. Here, we show that tRNS over the bilateral dorsolateral prefrontal cortices (dlPFCs) improved learning and performance of children with mathematical learning disabilities (MLD) during arithmetic training compared to those who received sham (placebo) tRNS. Training gains correlated positively with improvement on a standardized mathematical diagnostic test, and this effect was strengthened by tRNS. These findings mirror those in healthy adults, and encourage replications using larger cohorts. Overall, this study offers insights into the concept of combining tRNS and cognitive training for improving learning and cognition of children with learning disabilities.
“Transcranial random noise stimulation and cognitive training to improve learning and cognition of the atypically developing brain: A pilot study” by Chung Yen Looi, Jenny Lim, Francesco Sella, Simon Lolliot, Mihaela Duta, Alexander Alexandrovich Avramenko & Roi Cohen Kadosh in Scientific Reports. Published online July 5 2017 doi:10.1038/s41598-017-04649-x
Your Hands May Reveal the Struggle to Maintain Self Control
Source: Ohio State University.
Study shows decision-making in real time.
It takes just a few seconds to choose a cookie over an apple and wreck your diet for the day.
But what is happening during those few seconds while you make the decision?
In a new study, researchers watched in real time as people’s hands revealed the struggle they were under to choose the long-term goal over short-term temptation. The work represents a new approach to studying self-control.
In one key experiment, participants viewed pictures of a healthy and an unhealthy food choice on opposite sides of the top of a computer screen and moved a cursor from the center bottom to select one of the foods.
People who moved the cursor closer to the unhealthy treat (even when they ultimately made the healthy choice) later showed less self-control than did those who made a more direct path to the healthy snack.
“Our hand movements reveal the process of exercising self-control,” said Paul Stillman, co-author of the study and postdoctoral researcher in psychology at The Ohio State University.
“You can see the struggle as it happens. For those with low self-control, the temptation is actually drawing their hand closer to the less-healthy choice.”
The results may shed light on a scholarly debate about what’s happening in the brain when humans harness willpower.
Stillman conducted the study with Melissa Ferguson, professor of psychology, and Danila Medvedev, a former undergraduate student, both from Cornell University. Their research will appear in the journal Psychological Science.
The study involved several experiments. In one, 81 college students made 100 decisions involving healthy versus unhealthy food choices.
In each trial, they clicked a “Start” button at the bottom of the screen. As soon as they did, two images appeared in the upper-left and upper-right corners of the screen, one a healthy food (such as Brussels sprouts) and the other an unhealthy one (such as a brownie).
They were told to choose as quickly as possible which of the two foods would most help them meet their health and fitness goals. So there was a “correct” answer, even if they were tempted by a less healthy treat.
Before the experiment began, the participants were told that after they finished they would be given one of the foods they chose in the experiment. At the end, however, they could freely choose whether they wanted an apple or a candy bar.
The results showed that those who chose the candy bar at the end of the experiment – those with lower self-control – had tended to veer closer to the unhealthy foods on the screen.
“The more they were pulled toward the temptation on the computer screen, the more they actually chose the temptations and failed at self-control,” Stillman said.
But for those with higher levels of self-control, the path to the healthy food was more direct, indicating that they experienced less conflict.
In two other studies, similar results occurred in a completely different scenario, in which college students could decide whether they would rather accept $25 today or $45 in 180 days. Those with lower levels of self-control had mouse trajectories that were clearly different from those with higher self-control, suggesting differences in how they were dealing with the decisions.
“This mouse-tracking metric could be a powerful new tool to investigate real-time conflict when people have to make decisions related to self-control,” he said.
The findings also offer new evidence in a debate about how decision-making in self-control situations unfolds, Stillman said.
When the researchers mapped the trajectories people took with the cursor in the first experiment, they observed that most participants did not automatically start directly toward the unhealthy treat before abruptly switching course back to the healthy food. Rather, the trajectories appear curved, as if both the temptation and goal were competing from the beginning.
Why is that important?
Some researchers have argued that there are two systems in our brain that are involved in a self-control decision: one that’s impulsive and a second that overcomes the impulses to exert willpower. But if that were the case, the trajectories seen in this study should look different than they do, Stillman said.
If dual systems underlie these choices, there should be a relatively straight line toward the unhealthy food while people are under the influence of the impulsive first system and then an abrupt change in direction toward the healthy food as the system in charge of self-control kicks in.
“That’s not what we found,” Stillman said. “Our results suggest a more dynamical process in which the healthy and unhealthy choices are competing from the very beginning in our brains and there isn’t an abrupt change in thinking. That’s why we get these curved trajectories.”
Stillman said these results should help lead to a more accurate view of how our cognitive processes unfold to allow us to resist temptation.
Depression Affects Male and Female Brains Differently
Source: Frontiers.
New findings suggest that adolescent girls and boys might experience depression differently and that sex-specific treatments could be beneficial for adolescents.
When researchers in the UK exposed depressed adolescents to happy or sad words and imaged their brains, they found that depression has different effects on the brain activity of male and female patients in certain brain regions. The findings suggest that adolescent girls and boys might experience depression differently and that sex-specific treatments could be beneficial for adolescents.
Men and women appear to suffer from depression differently, and this is particularly striking in adolescents. By 15 years of age, girls are twice as likely to suffer from depression as boys. There are various possible reasons for this, including body image issues, hormonal fluctuations and genetic factors, where girls are more at risk of inheriting depression. However, differences between the sexes don’t just involve the risk of experiencing depression, but also how the disorder manifests and its consequences.
“Men are more liable to suffer from persistent depression, whereas in women depression tends to be more episodic,” explains Jie-Yu Chuang, a researcher at the University of Cambridge, and an author on the study, which was recently published in Frontiers in Psychiatry. “Compared with women, depressed men are also more likely to suffer serious consequences from their depression, such as substance abuse and suicide.” Despite this, so far, most researchers have focused on depression in women, likely because it is more common.
This motivated Chuang and her colleagues to carry out this latest study to find differences between depressed men and women. They recruited adolescent volunteers for the study, who were aged between 11 and 18 years. This included 82 female and 24 male patients who suffered from depression, and 24 female and 10 male healthy volunteers. The researchers imaged the adolescents’ brains using magnetic resonance imaging, while flashing happy, sad or neutral words on a screen in a specific order.
The volunteers pressed a button when certain types of words appeared and did not press the button when others appeared, and the researchers measured their brain activity throughout the experiment. When the researchers flashed certain combinations of words on the screen, they noticed that depression affects brain activity differently between boys and girls in brain regions such as the supramarginal gyrus and posterior cingulate.
So, what do these results mean? “Our finding suggests that early in adolescence, depression might affect the brain differently between boys and girls,” explains Chuang. “Sex-specific treatment and prevention strategies for depression should be considered early in adolescence. Hopefully, these early interventions could alter the disease trajectory before things get worse.”
The brain regions highlighted in the study have been previously linked to depression, but further work is needed to understand why they are affected differently in depressed boys, and if this is related to how boys experience and handle depression.
Because depression is more common in girls, the researchers were not able to recruit as many boys in this study, and future experiments should compare similar numbers of girls and boys for more representative results. Chuang and her colleagues would like to explore this phenomenon further. “I think it would be great to conduct a large longitudinal study addressing sex differences in depression from adolescence to adulthood.”
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Funding: Funding provided by Medical Research Council, NHS Health Technology Assessment (HTA) Programme, Central Manchester and Manchester Children’s University Hospitals NHS Trust.
Source: Melissa Cochrane – Frontiers
Image Source: NeuroscienceNews.com image is credited to the researchers/Frontiers.
Original Research: Full open access research for “Adolescent Major Depressive Disorder: Neuroimaging Evidence of Sex Difference during an Affective Go/No-Go Task” by Jie-Yu Chuang, Cindy C. Hagan, Graham K. Murray, Julia M. E. Graham, Cinly Ooi, Roger Tait, Rosemary J. Holt, Rebecca Elliott, Adrienne O. van Nieuwenhuizen, Edward T. Bullmore, Belinda R. Lennox, Barbara J. Sahakian, Ian M. Goodyer, and John Suckling in Frontiers in Psychiatry. Published online July 11 2017 doi:10.3389/fpsyt.2017.00119
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Frontiers “Depression Affects Male and Female Brains Differently.” NeuroscienceNews. NeuroscienceNews, 11 July 2017.
<http://neurosciencenews.com/depression-sex-differences-7059/>.
<http://neurosciencenews.com/depression-sex-differences-7059/>.
Abstract
Adolescent Major Depressive Disorder: Neuroimaging Evidence of Sex Difference during an Affective Go/No-Go Task
Compared to female major depressive disorder (MDD), male MDD often receives less attention. However, research is warranted since there are significant sex differences in the clinical presentation of MDD and a higher rate of suicide in depressed men. To the best of our knowledge, this is the first functional magnetic resonance imaging (fMRI) study with a large sample addressing putative sex differences in MDD during adolescence, a period when one of the most robust findings in psychiatric epidemiology emerges; that females are twice as likely to suffer from MDD than males. Twenty-four depressed and 10 healthy male adolescents, together with 82 depressed and 24 healthy female adolescents, aged 11–18 years, undertook an affective go/no-go task during fMRI acquisition. In response to sad relative to neutral distractors, significant sex differences (in the supramarginal gyrus) and group-by-sex interactions (in the supramarginal gyrus and the posterior cingulate cortex) were found. Furthermore, in contrast to the healthy male adolescents, depressed male adolescents showed decreased activation in the cerebellum with a significant group-by-age interaction in connectivity. Future research may consider altered developmental trajectories and the possible implications of sex-specific treatment and prevention strategies for MDD.
“Adolescent Major Depressive Disorder: Neuroimaging Evidence of Sex Difference during an Affective Go/No-Go Task” by Jie-Yu Chuang, Cindy C. Hagan, Graham K. Murray, Julia M. E. Graham, Cinly Ooi, Roger Tait, Rosemary J. Holt, Rebecca Elliott, Adrienne O. van Nieuwenhuizen, Edward T. Bullmore, Belinda R. Lennox, Barbara J. Sahakian, Ian M. Goodyer, and John Suckling in Frontiers in Psychiatry. Published online July 11 2017 doi:10.3389/fpsyt.2017.00119
Neural Stem Cells Steered by Electric Fields in Rat Brain
Summary: A recent study in Stem Cell Reports suggests electrical fields can be used to help guide transplanted neural stem cells towards a specific location in the brain. The finding could pave the way for new treatments that could help repair brain damage.
Source: UC Davis.
Electric fields can be used to guide neural stem cells transplanted into the brain towards a specific location. The research, published July 11 in the journal Stem Cell Reports, opens possibilities for effectively guiding stem cells to repair brain damage.
Professor Min Zhao at the University of California, Davis School of Medicine’s Institute for Regenerative Cures studies how electric fields can guide wound healing. Damaged tissues generate weak electric fields, and Zhao’s research has shown how these electric fields can attract cells into wounds to heal them.
“One unmet need in regenerative medicine is how to effectively and safely mobilize and guide stem cells to migrate to lesion sites for repair,” Zhao said. “Inefficient migration of those cells to lesions is a significant roadblock to developing effective clinical applications.”
Dr. Junfeng Feng, a neurosurgeon at Ren Ji Hospital, Shanghai Jiao Tong University and Shanghai Institute of Head Trauma, visited Zhao’s lab to study how electric fields might guide stem cells implanted in the brain.
Natural neural stem cells — cells that can develop into other brain tissues — are found deep in the brain, in the subventricular zone and hippocampus. To repair damage to the outer layers of the brain (the cortex), they have to migrate some distance, especially in the large human brain. Transplanted stem cells might also have to migrate some way to find an area of damage.
Stem Cells Move “Upstream”
Feng and Zhao developed a model of stem cell transplants in rats. They placed human neural stem cells in the rostral migration stream – a pathway in the rat brain that carries cells towards the olfactory bulb, which governs the animal’s sense of smell. Cells move along this pathway partly carried by the flow of cerebrospinal fluid and partly guided by chemical signals.
By applying an electric field within the rat’s brain, they found that they could get the transplanted stem cells to swim “upstream” against the fluid flow and natural cues and head for other locations within the brain.
The transplanted stem cells were still in their new locations weeks or months after treatment.
“Electrical mobilization and guidance of stem cells in the brain therefore provides a potential approach to facilitate stem cell therapies for brain diseases, stroke and injuries,” Zhao said.
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Additional authors on the paper are: at UC Davis, Lei Zhang, Jing Liu, Bruce Lyeth and Jan Nolta; Ji-Yao Jiang, Ren Ji Hospital, Shanghai Jiao Tong University and Shanghai Institute of Head Trauma; and Michael Russell, Aaken Laboratories, Davis.
Funding: The work was supported by the California Institute for Regenerative Medicine with additional support from NIH, NSF and Research to Prevent Blindness, Inc.
Source: Andy Fell – UC Davis
Image Source: NeuroscienceNews.com image is credited to Junfeng Feng.
Original Research: Full open access research for “Electrical Guidance of Human Stem Cells in the Rat Brain” by Jun-Feng Feng, Jing Liu, Lei Zhang, Ji-Yao Jiang, Michael Russell, Bruce G. Lyeth, Jan A. Nolta, and Min Zhao in Stem Cell Reports. Published online June 29 2017doi:10.1016/j.stemcr.2017.05.035
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UC Davis “Neural Stem Cells Steered by Electric Fields in Rat Brain.” NeuroscienceNews. NeuroscienceNews, 11 July 2017.
<http://neurosciencenews.com/genetics-stem-cells-neurobiology-7060/>.
<http://neurosciencenews.com/genetics-stem-cells-neurobiology-7060/>.
Abstract
Electrical Guidance of Human Stem Cells in the Rat Brain
Highlights
•Developed a technology and device delivering electric current to the brain in vivo
•Achieved stable delivery of currents to brain with monitoring and safety concerns
•Exhibited effective guidance of migration of transplanted human NSCs in live brain
•Demonstrated enhanced motility, survival, and differentiation of the guided hNSCs
Summary
Limited migration of neural stem cells in adult brain is a roadblock for the use of stem cell therapies to treat brain diseases and injuries. Here, we report a strategy that mobilizes and guides migration of stem cells in the brain in vivo. We developed a safe stimulation paradigm to deliver directional currents in the brain. Tracking cells expressing GFP demonstrated electrical mobilization and guidance of migration of human neural stem cells, even against co-existing intrinsic cues in the rostral migration stream. Transplanted cells were observed at 3 weeks and 4 months after stimulation in areas guided by the stimulation currents, and with indications of differentiation. Electrical stimulation thus may provide a potential approach to facilitate brain stem cell therapies.
“Electrical Guidance of Human Stem Cells in the Rat Brain” by Jun-Feng Feng, Jing Liu, Lei Zhang, Ji-Yao Jiang, Michael Russell, Bruce G. Lyeth, Jan A. Nolta, and Min Zhao in Stem Cell Reports. Published online June 29 2017 doi:10.1016/j.stemcr.2017.05.035
Visual System Changes That May Signal Parkinson’s Disease
Visual System Changes That May Signal Parkinson’s Disease
Source: RSNA.
Changes in the visual systems of newly diagnosed Parkinson’s disease patients may provide important biomarkers for the early detection and monitoring of the disease, according to a new study published online in the journal Radiology.
“Just as the eye is a window into the body, the visual system is a window into brain disorders,” said lead researcher Alessandro Arrigo, M.D., a resident in ophthalmology at the University Vita-Salute San Raffaele of Milan, Italy.
Parkinson’s disease is a neurodegenerative condition caused by neuronal loss in several brain structures. Parkinson’s disease is characterized by tremors, rigidity or stiffness throughout the body, and impaired balance and coordination.
“Although Parkinson’s disease is primarily considered a motor disorder, several studies have shown non-motor symptoms are common across all stages of the disease,” Dr. Arrigo said. “However, these symptoms are often undiagnosed because patients are unaware of the link to the disease and, as a result, they may be under-treated.”
Non-motor symptoms experienced by patients with Parkinson’s disease include visual alterations such as an inability to perceive colors, a change in visual acuity, and a decrease in blinking which can lead to dry eye.
“These non-motor Parkinson’s symptoms may precede the appearance of motor signs by more than a decade,” Dr. Arrigo said.
The study of 20 newly diagnosed and not yet treated patients (11 men, 9 women) with Parkinson’s disease and 20 age- and gender-matched healthy controls involved a multi-disciplinary team of researchers in ophthalmology, neurology and neuroradiology of the University of Messina, Italy. MRI was performed on both the healthy controls and the patients, who underwent imaging within four weeks of their diagnosis. Researchers used an MRI technique called diffusion weighted imaging to assess white matter changes and voxel-based morphometry (VBM) to investigate concentration changes of brain’s gray and white matter. All study participants also had ophthalmologic examinations.
The researchers found significant abnormalities within the visual system brain structures of Parkinson’s disease patients, including alterations of optic radiations, a reduction of white matter concentration and a reduction of optic chiasm volume. The optic chiasm is the part of the brain where the left and right optic nerves intersect.
“The study in depth of visual symptoms may provide sensitive markers of Parkinson’s disease,” Dr. Arrigo said. “Visual processing metrics may prove helpful in differentiating Parkinsonism disorders, following disease progression, and monitoring patient response to drug treatment.”
Dr. Arrigo added that future studies are needed to better understand the timing of degeneration along visual pathways, as well as the specific changes.
“We’re excited by our findings,” he said. “However, this is just a starting point.”
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Source: Queen Muse – RSNA
Image Source: NeuroscienceNews.com image is credited to RNSA.
Original Research: Full open access research for “Visual System Involvement in Patients with Newly Diagnosed Parkinson Disease” by Alessandro Arrigo, Alessandro Calamuneri, Demetrio Milardi, Enricomaria Mormina, Laura Rania, Elisa Postorino, Silvia Marino, Giuseppe Di Lorenzo, Giuseppe Pio Anastasi, Maria Felice Ghilardi, Pasquale Aragona, Angelo Quartarone, and Michele Gaeta in Radiology. Published online July 11 2017 doi:10.1148/radiol.2017161732
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RSNA “Visual System Changes That May Signal Parkinson’s Disease.” NeuroscienceNews. NeuroscienceNews, 11 July 2017.
<http://neurosciencenews.com/parkinsons-visual-changes-7061/>.
<http://neurosciencenews.com/parkinsons-visual-changes-7061/>.
Abstract
Visual System Involvement in Patients with Newly Diagnosed Parkinson Disease
Parkinson disease (PD) is a common neurodegenerative disease caused by dopaminergic neuronal loss in several brain structures, primarily in the substantia nigra. Although PD primarily is considered a motor disorder, results of several studies have shown that nonmotor symptoms are common throughout all stages of the disease. These symptoms are often undiagnosed because patients are embarrassed by them or unaware of their link to PD, and consequently, they may be undertreated.
Nonmotor symptoms encompass olfactory deficits, visual alterations, apathy, depression, pain, sexual difficulties, bowel incontinence, and sleep disorders. They usually precede the appearance of motor signs by more than a decade, in keeping with the progression of Lewy abnormalities. Although many patients with PD do not report visual problems, the disease can be associated with visual symptoms and signs that occur at different neural levels, including loss of visual acuity, difficulty with discrimination of contrast, alteration of color perception, impairment in visual skills in performing visual-spatial tasks, and difficulty in discriminating orientation and motion. In addition, eye movements and latency times of blinking and pupillary reflexes might be altered.
Retinal dysfunction might be partially responsible for some of the visual dysfunctions, because (a) retinal levels of dopamine are decreased in both patients with PD and in animal models of PD with visual electrophysiologic abnormalities that are similar to those reported in patients with PD and (b) electroretinographic abnormalities are present in both patients with and animal models of PD. In keeping with this interpretation, acute administration of levodopa induces recovery of the electrophysiologic abnormalities in both patients with and animal models of PD and relieves symptoms of visual blurring in patients. On the other hand, deficits at the cortical level might contribute to visual dysfunction, because results of studies have shown reduced metabolism and hypoperfusion in the occipital cortex of patients with PD. Moreover, authors of previous magnetic resonance (MR) imaging studies who used in vivo neuroanatomic quantitative approaches have reported significant focal reductions in cortical thickness of the occipital cortex in intermediate to advanced stages of the disease. Hence, the pathophysiologic basis of visual dysfunction in patients with PD requires further definition. On the basis of the existing literature, we hypothesized the presence of wide abnormalities in visual system pathways and related structures in patients with PD. The main aim of our study was to investigate the intracranial visual system in drug-naïve patients with newly diagnosed PD.
“Visual System Involvement in Patients with Newly Diagnosed Parkinson Disease” by Alessandro Arrigo, Alessandro Calamuneri, Demetrio Milardi, Enricomaria Mormina, Laura Rania, Elisa Postorino, Silvia Marino, Giuseppe Di Lorenzo, Giuseppe Pio Anastasi, Maria Felice Ghilardi, Pasquale Aragona, Angelo Quartarone, and Michele Gaeta in Radiology. Published online July 11 2017 doi:10.1148/radiol.2017161732