This monoamine (amino acid derivative) affects mood and is critical for motor function. Patients with Parkinson’s disease have low dopamine levels and become lethargic. The symptoms can be temporarily alleviated by administering the precursor L-dopa to boost dopamine production. The frontal lobes consume the most dopamine. Elevated levels are often seen in schizophrenia and could be a factor in bringing about hallucinations. Hallucinations caused by many psychoactive drugs are also thought to result from high dopamine levels.
The world’s first discovered neurotransmitter is an ester (a chemical compound derived from acids) involved in motor function, memory, attention, and learning. It can be a neuromodulator, altering synaptic sensitivity and the efficacy of other neurotransmitters. Its modulatory action involves how our levels of alertness and clarity of perception change. Alzheimer’s patients have low cortical acetylcholine levels and, when given medications increasing acetylcholine, their sensitivity, alertness, and memory typically improve.
Gamma-aminobutyric acid (GABA) is an inhibitory amino acid with a calming effect. Alcohol—with its powers of relaxation—mimics it, as do various tranquilizers.
Epinephrine (adrenaline) and norepinephrine are monoamines, which heighten energy levels as we experience fear or anger. These monoamines prepare us to fight or flee and act both as neurotransmitters and as stress hormones. Caffeine triggers epinephrine release, effectively inducing a mild fight-or-flight response.
Endorphins and Enkephalins
These are natural pleasure drugs. Athletes feel their effects during intense workouts. Endorphins are chemically similar to morphine and have comparable effects. They are natural painkillers and make it possible to push oneself further. Endorphins are found primarily in the brain, while enkephalins can be found in the rest of the body.