Acetylcholine – involved in voluntary movement, learning, memory, and sleep
§ Too much acetylcholine is associated with depression, and too little in the hippocampus has been associated with dementia.
Dopamine – correlated with movement, attention, and learning
§ Too much dopamine has been associated with schizophrenia, and too little is associated with some forms of depression as well as the muscular rigidity and tremors found in Parkinson’s disease.
Norepinephrine – associated with eating, alertness
§ Too little norepinephrine has been associated with depression, while an excess has been associated with schizophrenia.
Epinephrine – involved in energy, and glucose metabolism
§ Too little epinephrine has been associated with depression.
Serotonin – plays a role in mood, sleep, appetite, and impulsive and aggressive behavior
§ Too little serotonin is associated with depression and some anxiety disorders, especially obsessive-compulsive disorder. Some antidepressant medications increase the availability of serotonin at the receptor sites.
GABA (Gamma-Amino Butyric Acid) – inhibits excitation and anxiety
§ Too little GABA is associated with anxiety and anxiety disorders. Some anti-anxiety medication increases GABA at the receptor sites.
Endorphins – involved in pain relief and feelings of pleasure and contentedness
Sources: IB Psych, All Psych Online, University of Pennsylvania