Synapse Activity Decreases. These brain scans highlight dopamine receptors, with areas of highest density shown in red. The meth abuser has severely reduced receptor levels. Other drugs, including alcohol, cocaine, and heroin, have the same effect.
An overwhelming number of studies have reported age-related changes insynthesis, , and number of receptors. Studies using (PET) in living human subjects have shown a significant age-related decline in dopamine synthesis, notably in the and regions (excluding the ).
Significant age-related decreases in dopamine receptors, , and have also been highly reported.
A general decrease in D1 and D2 receptors has been shown, and more specifically a decrease of D1 and D2 receptor binding in theand .
A general decrease in D1 receptor density has also been shown to occur with age. Significant age-related declines in dopamine receptors, D2 and D3
were detected in thewikipedia.org , , lateral temporal cortex, , medial temporal cortex, , medial , and lateral thalamus.
One study also indicated a significant inverse correlation between dopamine binding in the occipital cortex and age.
Postmortem studies also show that the number of D1 and D2 receptors decline with age in both the caudate nucleus and the putamen, although the ratio of these receptors did not show age-related changes.
The loss of dopamine with age is thought to be responsible for many neurological symptoms that increase in frequency with age, such as decreased arm swing and increased.
Changes in dopamine levels may also cause age-related changes in cognitive flexibility.