@article{ref1,
title="Reaction Time Variability and Related Brain Activity in Methamphetamine Psychosis",
journal="Biological psychiatry",
year="2014",
author="Fassbender, Catherine and Lesh, Tyler A. and Ursu, Stefan and Salo, Ruth",
volume="77",
number="5",
pages="465-474",
abstract="BACKGROUND: This study investigated the dynamics of cognitive control instability in methamphetamine (MA) abuse, as well its relationship to substance-induced psychiatric symptoms and drug use patterns. <br><br>METHODS: We used an ex-Gaussian reaction time (RT) distribution to examine intraindividual variability (IIV) and excessively long RTs (tau) in an individual's RT on a Stroop task in 30 currently drug-abstinent (3 months to 2 years) MA abusers compared with 27 nonsubstance-abusing control subjects. All subjects underwent functional magnetic resonance imaging while performing the Stroop task, which allowed us to measure the relationship between IIV and tau to functional brain activity. <br><br>RESULTS: Elevated IIV in the MA compared with the control group did not reach significance; however, when the MA group was divided into those subjects who had experienced MA-induced psychosis (MAP+) (n = 19) and those who had not (n = 11), the MAP+ group had higher average IIV compared with the other groups (p <.03). In addition, although control subjects displayed a relationship between IIV and conflict-related brain activity in bilateral prefrontal cortex such that increased IIV was associated with increased activity, the MAP+ group displayed this relationship in right prefrontal cortex only, perhaps reflecting elevated vigilance in the MAP+ group. Greater IIV did not correlate with severity of use or months MA abstinent. No group differences emerged in tau values. <br><br>CONCLUSIONS: These results suggest increased cognitive instability in those MA-dependent subjects who had experienced MA-induced psychosis.<p /><p>Language: en</p>",
language="en",
issn="0006-3223",
doi="10.1016/j.biopsych.2014.07.028",
url="http://dx.doi.org/10.1016/j.biopsych.2014.07.028"
}