Methamphetamine dramatically affects the central nervous system (CNS). It acts as a potent CNS stimulant and is highly addictive. Several areas of the brain are affected: the nucleus accumbens, the prefrontal cortex and the striatum. Meth use causes the release of the neurotransmitters dopamine, norepinephrine and serotonin and blocks their re-uptake, which results in a sense of euphoria. Dopamine is the primary neurotransmitter that causes the enhanced mood and feelings of pleasure that accompanies meth abuse. Because meth is metabolized slowly, the high is longer and the potential for damage, including neurological damage, is greater than for other drugs of abuse. Whereas cocaine is metabolized in 1 hour, meth takes 12 hours. Meth is rapidly absorbed and reaches its peak effect in 2 to 3 hours. Continued meth use reduces the levels of dopamine in the brain and requires an increase in drug use to obtain the same sensations. This reduction in dopamine levels allows symptoms similar to those of Parkinson’s disease to become evident. One such symptom is compulsivity problems.46 Men more frequently suffer from pathological gambling and compulsive sexual behavior whereas women tend toward compulsive buying and binge eating. A unique manifestation of methamphetamine abuse is the development of stereotypy or punding defined as non-goal-directed repetitive activity for prolonged periods of time without any apparent gain.46 There is a predilection for these behaviors to entail activities in which users had previously been involved. For example, a carpenter may repetitively build wooden objects, an artist may draw or paint excessively or a businessman may make and add to spreadsheets for hours. There is also a gender-related component: men typically tinker with electronics and women engage in grooming behaviors such as hair brushing or nail polishing. Chronic methamphetamine abuse also significantly changes the brain. Brain imaging studies have demonstrated alterations in the activity of the dopamine system that are associated with reduced motor speed, emotion, reward, memory, cognitive skills and impaired verbal learning. 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). 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 or permanent.41 Since meth is a neurotoxin, abusing it can also result in irreversible damage to the brain including stroke, cerebral edema, cerebral hemorrhage, paranoia and hallucinations.30,34,39 Meth users describe themselves as brave, confident and energetic. Some users believe they have superpowers when high on meth which is why meth has been described as the ‘magic drug.’ Meth combines the hyperactivity of cocaine use with the delusions of LSD use.
Short-term CNS effects of meth abuse include insomnia, hyperactivity, decreased appetite and tremors. Extended meth abuse can cause depletion of monoamines in the brain, which can have a deleterious effect on learning. Long-term use of meth can also lead to psychological addiction, stroke, violent behavior, aggressiveness, anxiety, confusion, auditory hallucinations, mood disturbances, delusions, insomnia, seizures and short-or long-term psychosis. Withdrawal from the drug produces severe depression, anxiety, fatigue, paranoia, aggression, increased appetite and extreme cravings for the drug.34