Methamphetamine and Brain Function
According to the Centers for Disease Control, methamphetamine, or meth as it is often referred to, is considered the fastest-growing illicit drug in the United States. The consequences of usage are detrimental to families and employers, not to mention the increasing law enforcement burden of having to find and disband labs making it illegally. (CDC, 2005) Aside from the far-reaching implications of methamphetamine use on these entities, this paper explores the effect methamphetamine has on the structure and function of the human brain.
A study by Nestor et al. (2011) explored prefrontal hypoactivation during cognitive control in early abstinent methamphetamine-dependent subjects. Cognitive control is the ability to process incoming information and respond with the appropriate behavior. The participants consisted of an 18 member control group who had not previously used meth and a 10 member experimental group who were 4 to 7 days removed from their last meth usage. The researchers utilized the Stroop test which focuses on one stimulus dimension while ignoring another dimension, in this case indicating the color of the letters the word was written in instead of naming the written color word as spelled, in an incongruent color. This task was performed by each individual while their brain activation was evaluated by functional MRI (fMRI). The fMRI works on the premise that the more active a brain area is, the more oxygen it will require, which results in increased blood flow to that area. Regarding the Stroop test alone, the meth-dependent group showed slower response times and made more errors than the control group. The fMRI results also showed the complementary result of significantly less activation in prefrontal areas of the brain in the meth-dependent subjects than in the control group. The end result of the study suggests that the cognitive control deficits impact the success of treatment for addiction to meth. (Nestor et al., 2011)
Salo et al. (2009) also investigated the role of methamphetamine in prefrontal cortex activity. They conducted one of the first studies revealing abnormal trial-to-trial data about meth users when required to exhibit learned behavioral control. The expectation of the study was that meth users, unlike those who had no substance abuse problem, would fail to learn from previous mistakes and avoid the same behaviors. 12 lifetime methamphetamine addicts were compared to 16 non-substance abusers of the same age. Similar to the previous study, the Stroop test was utilized with modifications to show differences in groups between error rates, response times, and amount of adjustments between trials. Again the Stroop test and fMRI scans were conducted simultaneously over multiple trials. As expected, meth abusers showed lower trial-to-trial response times. The study was more specific in that the fMRI implicated not only the right prefrontal cortex in the maladjustments, but also the...