Stimulants are a classification of drugs "that elevate mood, increase feelings of well-being, and increase energy and alertness," according to the National Institute of Drug Abuse (NIDA). The Connecticut Clearinghouse adds that stimulants also increase activity in both the brain and spinal cord. Many stimulants are abused, like cocaine and methamphetamines, which have short-term and long-term effects on the brain.
Cocaine Effects
Cocaine works by interfering with the brain neurotransmitter dopamine, blocking its reabsorption, according to the Connecticut Clearinghouse; the cocaine molecule binds to the dopamine transporter molecule on the post-synaptic cleft, which is where the extra dopamine would be taken in to be recycled. As a result, more dopamine is available for use, resulting in strong feelings of pleasure. When a person uses cocaine for a long time, the brain decreases the amount of dopamine receptors to compensate. If the person continues to use cocaine after that point, she will need to take more to reach her previous high; if she discontinues use, she will experience cravings from the lower dopamine levels. In addition to the changes in dopamine levels, cocaine also affects the prefrontal cortex and amygdala, which are involved in memory and learning.
Methamphetamine Effects
Methamphetamines interfere with dopamine and norepinephrine because methamphetamines have a similar chemical structure to these neurotransmitters, according to the Connecticut Clearinghouse. Instead of preventing the reabsorption of either dopamine or norepinephrine, methamphetamines block the breakdown of these neurotransmitters, which results in pleasure, alertness and decrease in fatigue. Methamphetamines also redirect where dopamine and norepinephrine are released; the Connecticut Clearinghouse states that methamphetamines are "carried into the nerve terminals by transporter molecules that normally carry dopamine or norepinephrine from the synapse back into the nerve terminal," resulting in a release in the nucleus accumbens, prefrontal cortex and striatum.
Long-Term Effects
Besides affecting neurotransmitter levels, stimulants can result in long-term damage to the brain. The Connecticut Clearinghouse states that either a high-dose or prolonged exposure can damage up to 50 percent of dopamine-producing neurons; some scientists hypothesize that this could lead to Parkinson's disease. Other serious effects include paranoia, hallucinations, cerebral edema and brain hemorrhage.
