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Elevated intraindividual variability in methamphetamine dependence is associated with poorer everyday functioning

Erin E Morgan1, Katie L Doyle2, Arpi Minassian1

  • 1Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA.

Psychiatry Research
|August 2, 2014
PubMed

Insights

Methamphetamine dependence elevates neurocognitive intraindividual variability (IIV), indicating cognitive dyscontrol. This heightened IIV in methamphetamine users is linked to poorer daily functioning and real-world problems.

Area of Science:

  • Neuroscience
  • Psychology
  • Addiction Research

Background:

  • Methamphetamine dependence is linked to executive dysfunction.
  • Neurocognitive intraindividual variability (IIV) reflects cognitive dyscontrol and predicts daily functioning issues.
  • No prior studies have investigated IIV in methamphetamine dependence.

Purpose of the Study:

  • To examine neurocognitive intraindividual variability (IIV) in methamphetamine-dependent individuals.
  • To determine the relationship between IIV and daily functioning in this population.

Main Methods:

  • A vigilance task was administered to 35 methamphetamine-dependent (MA+) and 55 non-using (MA-) participants.
  • A mixed model ANOVA controlled for covariates including education, mean reaction time, global cognitive performance, and HIV status.
  • Neuropsychological and performance-based measures of everyday functioning were assessed.

Main Results:

  • Methamphetamine-dependent individuals exhibited significantly elevated IIV compared to controls.
  • Elevated IIV was consistent across all blocks of the vigilance task.
  • Within the MA group, higher IIV correlated with executive dysfunction, slower reaction times, recent MA use, poorer driving simulation performance, impaired functional skills, and increased cognitive complaints.

Conclusions:

  • Methamphetamine users show increased neurocognitive intraindividual variability (IIV), suggesting cognitive dyscontrol.
  • Elevated IIV in MA users is associated with deficits in executive function and psychomotor speed.
  • This cognitive dyscontrol may contribute to the real-world functional impairments observed in methamphetamine dependence.
Keywords:
Activities of daily livingCognitive controlNeuropsychological assessmentSubstance dependenceWithin-person variability

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