title: Elevated intraindividual variability in methamphetamine dependence is associated with poorer everyday functioning.
abstract: Methamphetamine (MA) dependence is associated with executive dysfunction, but no studies have evaluated MA-related elevations in neurocognitive intraindividual variability (IIV), an expression of cognitive dyscontrol linked to poor daily functioning in populations with frontal systems injury. We examined IIV during a vigilance task in a well-characterized sample of 35 MA-dependent (MA+) and 55 non-MA using comparison participants (MA-) as part of a larger neuropsychological battery that included self-report and performance-based measures of everyday functioning. A mixed model ANOVA was conducted while controlling for covariates, including factors that differed between the groups (e.g., education) and those with conceptual relevance to IIV: mean reaction time, global cognitive performance, and HIV-infection (which was comparable across groups; p=0.32). This analysis revealed significantly elevated IIV among MA+ relative to MA- individuals that was comparable in magnitude across all trial blocks of the vigilance task. Within the MA group, elevated IIV was associated with executive dysfunction, psychomotor slowing, and recency of MA use, as well as poorer automobile driving simulator performance, worse laboratory-based functional skills, and more cognitive complaints. MA-users are vulnerable to IIV elevation, likely due to cognitive dyscontrol, which may increase their risk of real-world problems.
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA. Electronic address: eemorgan@ucsd.edu.
authors: Erin E
authors: EE
authors: Morgan
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA; SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA.
authors: Katie L
authors: KL
authors: Doyle
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA.
authors: Arpi
authors: A
authors: Minassian
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA.
authors: Brook L
authors: BL
authors: Henry
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA.
authors: William
authors: W
authors: Perry
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA.
authors: Thomas D
authors: TD
authors: Marcotte
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA.
authors: Steven Paul
authors: SP
authors: Woods
authors: Department of Psychiatry, University of California-San Diego, La Jolla, CA, USA.
authors: Igor
authors: I
authors: Grant
mesh_terms: D000328:Adult; D019969:Amphetamine-Related Disorders / Q000150:complications / Q000523:psychology*; D001288:Attention / Q000502:physiology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000523:psychology; D006801:Humans; D008297:Male; D008694:Methamphetamine; D008875:Middle Aged; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology; D057566:Self Report
chemical_list: D008694:Methamphetamine
keywords: Activities of daily living; Cognitive control; Neuropsychological assessment; Substance dependence; Within-person variability