Function in other brain regions did not recover even after 14 months of abstinence, indicating that some methamphetamine-induced changes are very long lasting. 16 This recovery was associated with improved performance on motor and verbal memory tests. 15 Another neuroimaging study showed neuronal recovery in some brain regions following prolonged abstinence (14 but not 6 months). 14 A similar study found that while biochemical markers for nerve damage and viability persist in the brain through 6 months of abstinence from methamphetamine, those markers return to normal after a year or more without taking the drug. In the study just mentioned, abstinence from methamphetamine resulted in less excess microglial activation over time, and users who had remained methamphetamine-free for 2 years exhibited microglial activation levels similar to the study’s control subjects. Some of the neurobiological effects of chronic methamphetamine misuse appear to be, at least, partially reversible. A study using brain imaging found more than double the levels of microglial cells in people who previously misused methamphetamine compared to people with no history of methamphetamine misuse, which could explain some of the neurotoxic effects of methamphetamine. Too much activity of the microglial cells, however, can assault healthy neurons. These cells support brain health by defending the brain against infectious agents and removing damaged neurons. Methamphetamine misuse also has been shown to have negative effects on non-neural brain cells called microglia. With prolonged abstinence, dopamine transporters in this area can be restored. Methamphetamine misuse greatly reduces the binding of dopamine to dopamine transporters (highlighted in red and green) in the striatum, a brain area important in memory and movement. Recovery of Brain Dopamine Transporters in Chronic Methamphetamine (METH) Users 12 These changes in brain structure and function could explain why methamphetamine addiction is so hard to treat and has a significant chance of relapse early in treatment. The two effects were correlated, suggesting that the structural change underlies the decline in mental flexibility. ![]() Research in primate models has found that methamphetamine alters brain structures involved in decision-making and impairs the ability to suppress habitual behaviors that have become useless or counterproductive. 6,7,8 Studies in chronic methamphetamine users 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 these individuals. Neuroimaging studies have demonstrated alterations in the activity of the dopamine system that are associated with reduced motor speed and impaired verbal learning. These and other problems reflect significant changes in the brain caused by misuse of methamphetamine. 48 Psychotic symptoms can sometimes last for months or years after a person has quit using methamphetamine, and stress has been shown to precipitate spontaneous recurrence of methamphetamine psychosis in people who use methamphetamine and have previously experienced psychosis. 47 They also may display a number of psychotic features, including paranoia, visual and auditory hallucinations, and delusions (for example, the sensation of insects creeping under the skin). In addition to being addicted to methamphetamine, people who use methamphetamine long term may exhibit symptoms that can include significant anxiety, confusion, insomnia, mood disturbances, and violent behavior. 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 abusers may develop difficulty feeling any pleasure other than that provided by the drug, fueling further abuse. Abusers often need to take higher doses of the drug, take it more frequently, or change how they take it in an effort to get the desired effect. Addiction is a chronic, relapsing disease, characterized by compulsive drug seeking and use and accompanied by functional and molecular changes in the brain.Īs is the case with many drugs, tolerance to methamphetamine’s pleasurable effects develops when it is taken repeatedly. Long-term methamphetamine abuse has many negative consequences, including addiction.
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