Meth appears to have a neurotoxic effect, damaging brain cells that contain the neurotransmitters dopamine and serotonin. In the short term, meth causes mind and mood changes, such as anxiety and depression, and increased heart rate and blood pressure. People who overdose on meth experience high body temperatures and convulsions, which if not treated, can result in death. Long-term effects can include paranoid or delusional thinking, violent behavior, memory loss, tooth decay and loss, malnutrition, and skin disorders. (Many people who use meth long term start picking at or scratching their skin, believing there are insects under its surface.) Some of these symptoms can persist for months or even years after a person has quit using meth, because long-term meth use can change the structure of the brain, particularly in areas associated with emotion and memory. When people don’t recover quickly after quitting, it’s harder for them to keep from using again. Injecting meth is also linked to increased transmission of infectious diseases, especially hepatitis and HIV/AIDS.
