Editing Causes of mental disorders (section)

===Neurotransmitter systems===
Abnormal levels of [[dopamine]] activity correspond with several disorders (reduced in [[ADHD]] and [[OCD]], and increased in schizophrenia). The dysfunction in [[serotonin]] and other [[monoamine]] neurotransmitters ([[norepinephrine]] and [[dopamine]]) correspond with certain mental disorders and their associated neural networks. Some include [[Major depressive disorder|major depression]], [[Obsessive compulsive disorder|obsessive-compulsive disorder]], [[phobias]], [[post-traumatic stress disorder]], and [[generalized anxiety disorder]]. Studies of depleted levels of [[monoamine]] neurotransmitters show an association with depression and other psychiatric disorders, but "... it should be questioned whether 5-HT [serotonin] represents just one of the final and not the main, factors in the neurological chain of events underlying psychopathological symptoms...."

Simplistic "chemical imbalance" explanations for mental disorders have never received empirical support; and most prominent psychiatrists, neuroscientists, and psychologists have not espoused such ill-defined, facile etiological theories. Instead, neurotransmitter systems have been understood in the context of the [[Diathesis–stress model|diathesis-stress]] or [[Biopsychosocial|biopsychosocial models]]. The following 1967 quote from renowned psychiatric and neuroscience researchers exemplifies this more sophisticated understanding (in contrast to the woolly "chemical imbalance" notion).

Whereas specific genetic factors may be of importance in the etiology of some, and possibly all, depressions, it is equally conceivable that early experiences of the infant or child may cause enduring biochemical changes, that may predispose some individuals to depressions in adulthood. It is not likely that changes in the metabolism of the biogenic amines alone will account for the complex phenomena of normal or pathological affect.