Can abstinence resolve brain changes caused by methamphetamine?
Methamphetamine is, essentially, a stimulant powder that is used for treatments of Attention-Deficit-Hyperactivity-Disorder (ADHD) and obesity, but is unfortunately also abused as a recreational drug. It has been shown to produce structural brain changes, which may, in fact, be permanent.
Specifically, research has shown that meth can produce long-term neural damage and cognitive impairment. It has also resulted in decreased dopamine transporter count (responsible for detecting the neurotransmitter dopamine), and lower brain metabolism in the striatum (facilitate voluntary movement) and thalamus. However, thalamic metabolism significantly improved after <6 months of abstinence, and thalamic metabolism completely recovered after 12–17 months of abstinence. Striatum metabolism did not entirely heal however, and thus there could be slight long-lasting changes due to meth. Thus, although the striatum metabolism is more dubious, it can be suggested that your thalamic function will restore to normal levels after a year. Moreover, people who were abstinent for methamphetamine (MA) for an average of 1.5 years still showed reduced glucose metabolism in the frontal lobe compared to controls. Another major consistent long-term finding is the reduction of Dopamine Transporters (DATs) in several brain regions, including the striatum.
Nevertheless, I would argue that all regions of your brain can largely entirely revert to its original form, or become even better, with abstinence. Long-term abstinence (1–5 years) showed to restore brain metabolic levels to the same level as controls, suggesting that the brain adapts to its substance-free environment to restore to normal metabolic levels.
Moreover, DAT transporters showed to increase in the striatum after 12–17 months of abstinence, thus suggesting their return to normalcy and indicating that abstinence can restore original brain function.
Nevertheless, further evidence shows that decision-making and emotional symptoms significantly improve with duration of abstinence for up to 1 year, suggesting that the brain does significantly revert to its original states following a year.
Moreover, affected grey matter is restored to baseline levels after abstinence following addiction; more surprisingly, grey matter volume increases greater than those who were never addicted in the first place (implying that they have developed further neural connections and learnt from the experience). Thus, not only can your brain heal, but it can also grow.
Overall, the knowledge is quite mixed, and limited due to the small sample size and confounding factors in research. However, based on current knowledge, I would believe that a year is enough to induce significant neural recovery and that, if abstinence is continued, its neurotoxic effects will continue to reverse over time. However, clearly, better than abstinence is the sagacity to not ever consume methamphetamine for recreational purposes in the first place.