I was reading about Dementia, Psychosis, Anti-psychotic drugs that are not good for Dementia, and pain. And there is a relationship in all these issues. Some anti-histamine drugs can cause Dementia too. Some anti-psychotic drugs make one less motivated and more depressed. And eating acetylcholine-rich foods feed the brain and some times remove the pain.
Over time, pain can wreck havoc to the nucleus accumbens in the brain. 20 years before Dementia is diagnosed, you will notice less motivation and more depression. Could it be that the brain’s nucleus accumbens is affected by some inflammation or imbalance in neurotransmitters?
Before we reach the age of 65, we have to ensure that starting the age of 40 we have led a healthy lifestyle (whole foods, exercise, sleep, not over medicated).
The most abundant dietary sources of choline—a precursor to acetylcholine—are animal fats such as egg yolks, cream, fatty cheeses, fatty fish, fatty meats, and liver. Non-animal sources include avocadoes and almonds.
The Brain, Nucleus Accumbens
The Stanford scientists focused on the nucleus accumbens, a brain structure known to be involved in computing the behavioral strategies that prompt us to seek or avoid things that can affect our survival. They found that chronic pain permanently changed certain connections to the nucleus accumbens, causing an enduring downshift in the excitation transmitted by them. Importantly, Malenka’s group showed that a particular brain chemical called galanin plays a critical role in this enduring suppression of nucleus accumbens excitability.
Galanin is a short signaling-protein snippet secreted by certain cells in various places in the brain. While its presence in the brain has been known for a good 60 years or so, galanin’s role is not well-defined and probably differs widely in different brain structures. There have been hints, though, that galanin activity might play a role in pain. For example, it’s been previously shown in animal models that galanin levels in the brain increase with the persistence of pain.
Being in pain is quite uncomfortable for most people. Even minor pain, such as a stubbed toe or a paper cut, is unpleasant but that pain fades relatively quickly. Imagine being in pain that never fades, or that fades only to come back a few hours later. What would that do to a person? This is what people with chronic pain have to deal with every day.
Chronic pain, a diagnosis including arthritis, back pain, and recurring migraines, can have a profound effect on a person’s day to day life when it goes untreated. People dealing with ongoing or long-term pain can become irritable, short-tempered, and impatient, and with good reason. Constant pain raises the focus threshold for basic functioning, which leaves the pained person with a greatly reduced ability to find solutions or workarounds to even relatively mundane problems. Something like a traffic jam, which most people would be mildly annoyed by but ultimately take in stride, could seriously throw off the rhythm of someone who is putting forth so much effort just to get through the day.
After a while, pain wears a person down, draining their energy and sapping their motivation. They sometimes attempt to limit social contact in an effort to reduce stress and to decrease the amount of energy they have to spend reacting to their environment. Eventually, many people with chronic pain develop depression-like symptoms: lack of interpersonal interaction, difficulty concentrating on simple tasks, and the desire to simplify their life as much as possible, which often manifests as seeking isolation and quiet. Sleeping often makes the pain less intrusive, and that combined with the exhaustion that pain induces means that it isn’t uncommon for a person to start sleeping upwards of ten hours a day.
Some recent studies have also shown that chronic pain can actually affect a person’s brain chemistry and even change the wiring of the nervous system. Cells in the spinal cord and brain of a person with chronic pain, especially in the section of the brain that processes emotion, deteriorate more quickly than normal, exacerbating many of the depression-like symptoms. It becomes physically more difficult for people with chronic pain to process multiple things at once and react to ongoing changes in their environment, limiting their ability to focus even more. Sleep also becomes difficult, because the section of the brain that regulates sense-data also regulates the sleep cycle. This regulator becomes smaller from reacting to the pain, making falling asleep more difficult for people with chronic pain.
In addition to making some symptoms more profound, the change in brain chemistry can, create new ones, as well. The most pronounced of these are anxiety and depression. After enough recurring pain, the brain rewires itself to anticipate future bouts, which makes patients constantly wary and causes significant anxiety related to pain. Because chronic pain often mimics depression by altering how a person’s brain reacts to discomfort and pain, chronic pain often biologically creates a feeling of hopelessness and makes it more difficult to process future pain in a healthy way. In fact, roughly one third of patients with chronic pain develop depression at some point during their lifetime.
Untreated pain creates a downward spiral of chronic pain symptoms, so it is always best to treat pain early and avoid chronic pain. This is why multidisciplinary pain clinics should be involved for accurate diagnosis and effective intervention early in the course of a painful illness – as soon as the primary care provider runs out of options that they can do themselves such as physical therapy or medications. However, even if the effects of chronic pain have set in, effective interdisciplinary treatment may significantly reduce the consequences of pain in their lives. There are any number of common treatments, which include exercise, physical therapy, a balanced diet, and prescription pain medication. Ultimately, effective treatment depends on the individual person and the specific source of the pain. One thing is very clear, however: the earlier a person begins effective treatment, the less the pain will affect their day-to-day life.
Phenethylamine and tyramine: Phenethylamine and tyramine are trace amine compounds which are synthesized in several types of CNS neurons, including all dopamine neurons. Specifically, these neurotransmitters act within the dopaminergic inputs to the NAcc. These substances regulate the presynaptic release of dopamine through their interactions with VMAT2 and TAAR1, analogous to amphetamine.
Glucocorticoids and dopamine: Glucocorticoid receptors are the only corticosteroid receptors in the nucleus accumbens shell. L-DOPA, steroids, and specifically glucocorticoids are currently known to be the only known endogenous compounds that can induce psychotic problems, so understanding the hormonal control over dopaminergic projections with regards to glucocorticoid receptors could lead to new treatments for psychotic symptoms. A recent study demonstrated that suppression of the glucocorticoid receptors led to a decrease in the release of dopamine, which may lead to future research involving anti-glucocorticoid drugs to potentially relieve psychotic symptoms.
GABA: A recent study on rats that used GABA agonists and antagonists indicated that GABAA receptors in the NAc shell have inhibitory control on turning behavior influenced by dopamine, and GABAB receptors have inhibitory control over turning behavior mediated by acetylcholine.
Glutamate: Studies have shown that local blockade of glutamatergic NMDA receptors in the NAcc core impaired spatial learning. Another study demonstrated that both NMDA and AMPA (both glutamate receptors) play important roles in regulating instrumental learning.
Serotonin (5-HT): Overall, 5-HT synapses are more abundant and have a greater number of synaptic contacts in the NAc shell than in the core. They are also larger and thicker, and contain more large dense core vesicles than their counterparts in the core.
Current models of addiction from chronic drug use involve alterations in gene expression in the mesocorticolimbic projection. The most important transcription factors that produce these alterations are ΔFosB, cyclic adenosine monophosphate (cAMP) response element binding protein (CREB), and nuclear factor kappa B (NFκB). ΔFosB is the most significant gene transcription factor in addiction since its viral or genetic overexpression in the nucleus accumbens is necessary and sufficient for many of the neural adaptations and behavioral effects (e.g., expression-dependent increases in self-administration and reward sensitization) seen in drug addiction. ΔFosB overexpression has been implicated in addictions to alcohol (ethanol), cannabinoids, cocaine, methylphenidate, nicotine, opioids, phencyclidine, propofol, and substituted amphetamines, among others. Increases in nucleus accumbens ΔJunD expression can reduce or, with a large increase, even block most of the neural alterations seen in chronic drug abuse (i.e., the alterations mediated by ΔFosB).
ΔFosB also plays an important role in regulating behavioral responses to natural rewards, such as palatable food, sex, and exercise. Natural rewards, like drugs of abuse, induce ΔFosB in the nucleus accumbens, and chronic acquisition of these rewards can result in a similar pathological addictive state through ΔFosB overexpression. Consequently, ΔFosB is the key transcription factor involved in addictions to natural rewards as well; in particular, ΔFosB in the nucleus accumbens is critical for the reinforcing effects of sexual reward. Research on the interaction between natural and drug rewards suggests that psychostimulants and sexual behavior act on similar biomolecular mechanisms to induce ΔFosB in the nucleus accumbens and possess cross-sensitization effects that are mediated through ΔFosB.
Similar to drug rewards, non-drug rewards also increase the level of extracellular dopamine in the NAcc shell. Drug-induced dopamine release in the NAcc shell and NAcc core is usually not prone to habituation (i.e., the development of drug tolerance: a decrease in dopamine release from future drug exposure as a result of repeated drug exposure); on the contrary, repeated exposure to drugs that induce dopamine release in the NAcc shell and core typically results in sensitization (i.e., the amount of dopamine that is released in the NAcc from future drug exposure increases as a result of repeated drug exposure). Sensitization of dopamine release in the NAcc shell following repeated drug exposure serves to strengthen stimulus-drug associations (i.e., classical conditioning that occurs when drug use is repeatedly paired with environmental stimuli) and these associations become less prone to extinction (i.e., “unlearning” these classically conditioned associations between drug use and environmental stimuli becomes more difficult). After repeated pairing, these classically conditioned environmental stimuli (e.g., contexts and objects that are frequently paired with drug use) often become drug cues which function as secondary reinforcers of drug use (i.e., once these associations are established, exposure to a paired environmental stimulus triggers a craving or desire to use the drug which they’ve become associated with).
In contrast to drugs, the release of dopamine in the NAcc shell by many types of rewarding non-drug stimuli typically undergoes habituation following repeated exposure (i.e., the amount of dopamine that is released from future exposure to a rewarding non-drug stimulus normally decreases as a result of repeated exposure to that stimulus).
|Form of neuroplasticity
or behavioral plasticity
|Type of reinforcer||Sources|
|Opiates||Psychostimulants||High fat or sugar food||Sexual intercourse||Physical exercise
|ΔFosB expression in
nucleus accumbens D1-typeMSNs
|Escalation of intake||Yes||Yes||Yes|||
conditioned place preference
|Reinstatement of drug-seeking behavior||↑||↑||↓||↓|||
in the nucleus accumbens
|Sensitized dopamine response
in the nucleus accumbens
|Altered striatal dopamine signaling||↓DRD2, ↑DRD3||↑DRD1, ↓DRD2, ↑DRD3||↑DRD1, ↓DRD2, ↑DRD3||↑DRD2||↑DRD2|||
|Altered striatal opioid signaling||No change or
|↑μ-opioid receptors||↑μ-opioid receptors||No change||No change|||
|Changes in striatal opioid peptides||↑dynorphin
No change: enkephalin
|Mesocorticolimbic synaptic plasticity|
|Number of dendrites in the nucleus accumbens||↓||↑||↑|||
|Dendritic spine density in
the nucleus accumbens
In April 2007, two research teams reported on having inserted electrodes into the nucleus accumbens in order to use deep brain stimulation to treat severe depression. In 2010, experiments reported that deep brain stimulation of the nucleus accumbens was successful in decreasing depression symptoms in 50% of patients who did not respond to other treatments such as electroconvulsive therapy. Nucleus accumbens has also been used as a target to treat small groups of patients with therapy-refractory obsessive-compulsive disorder.