What are the short-term (immediate) effects of methamphetamine abuse?

As a powerful stimulant, methamphetamine, even in small doses, can be addictive, can increase wakefulness and physical activity and decrease appetite. Methamphetamine can also cause a variety of cardiovascular problems, including rapid heart rate, irregular heartbeat, and increased blood pressure. Hyperthermia (elevated body temperature) and convulsions may occur with methamphetamine overdose, and if not treated immediately, can result in death.

Most of the pleasurable effects of methamphetamine are believed to result from the release of very high levels of the neurotransmitter dopamine. Dopamine is involved in motivation, the experience of pleasure, and motor function, and is a common mechanism of action for most drugs of abuse. The elevated release of dopamine produced by methamphetamine is also thought to contribute to the drug’s deleterious effects on nerve terminals in the brain.

What are the long-term effects of methamphetamine abuse?

Long-term methamphetamine abuse has many negative consequences, including addiction. Addiction is a chronic, relapsing disease, characterized by compulsive drug seeking and use, accompanied by functional and molecular changes in the brain. In addition to being addicted to methamphetamine, chronic abusers exhibit symptoms that can include anxiety, confusion, insomnia, mood disturbances, and violent behavior. They also can display a number of psychotic features, including paranoia, visual and auditory hallucinations, and delusions (for example, the sensation of insects creeping under the skin). Psychotic symptoms can sometimes last for months or years after methamphetamine abuse has ceased, and stress has been shown to precipitate spontaneous recurrence of methamphetamine psychosis in formerly psychotic methamphetamine abusers.

With chronic abuse, tolerance to methamphetamine’s pleasurable effects can develop. In an effort to intensify the desired effects, abusers may take higher doses of the drug, take it more frequently, or change their method of drug intake. Withdrawal from methamphetamine occurs when a chronic abuser stops taking the drug; symptoms of withdrawal include depression, anxiety, fatigue, and an intense craving for the drug.

Chronic methamphetamine abuse also significantly changes the brain. Specifically, brain imaging studies have demonstrated alterations in the activity of the dopamine system that are associated with reduced motor speed and impaired verbal learning. Recent studies in chronic methamphetamine abusers have also revealed severe structural and functional changes in areas of the brain associated with emotion and memory, which may account for many of the emotional and cognitive problems observed in chronic methamphetamine abusers.

Fortunately, some of the effects of chronic methamphetamine abuse appear to be, at least partially, reversible. A recent neuroimaging study showed recovery in some brain regions following prolonged abstinence (2 years, but not 6 months). This was associated with improved performance on motor and verbal memory tests. However, function in other brain regions did not display recovery even after 2 years of abstinence, indicating that some methamphetamine-induced changes are very long-lasting. Moreover, the increased risk of stroke from the abuse of methamphetamine can lead to irreversible damage to the brain.

Reprinted with permission from the National Institute on Drug Abuse