Elsevier

Biological Psychiatry

Volume 65, Issue 8, 15 April 2009, Pages 706-709
Biological Psychiatry

Brief Report
Impaired Prefrontal Cortical Function and Disrupted Adaptive Cognitive Control in Methamphetamine Abusers: A Functional Magnetic Resonance Imaging Study

https://doi.org/10.1016/j.biopsych.2008.11.026Get rights and content

Background

Methamphetamine (MA) abuse is associated with neurotoxicity to frontostriatal brain regions with deleterious effects on cognitive processes. Deficits in behavioral control are thought to be one contributing factor to the sustainment of addictive behaviors in MA abuse.

Methods

In order to examine patterns of behavioral control relevant to addiction, we employed a fast-event-related functional magnetic resonance imaging design to examine trial-to-trial reaction time (RT) adjustments in 12 MA-dependent subjects and 16 non-substance-abusers. A variant of the Stroop task was employed to contrast the groups on error rates, RT conflict, and the level of trial-to-trial adjustments seen after incongruent trials.

Results

The MA abusers exhibited reduced RT adjustments and reduced activation in the right prefrontal cortex compared to controls on conditions that measured the ability to use exposure to conflict situations (i.e., conflict trials) to regulate behavior. The groups did not differ on accuracy rates or within-trial Stroop conflict effects.

Conclusions

The observed deficits in trial-to-trial RT adjustments suggest that the ability to adapt a behavioral response based on prior experience may be compromised in MA abusers. These failures to modify behavior based on prior events may reflect a deficit that contributes to drug-seeking behavior.

Section snippets

Subjects

Two groups were studied: 12 MA abusing subjects and 16 age-matched non-substance-abusing control subjects. The MA abusers met DSM-IV criteria for lifetime MA dependence determined from the Structured Clinical Interview (SCID) (19) but were currently drug abstinent a minimum of 3 weeks (see Table 1).

Procedure

A single-trial Stroop task was administered during the scanning session that employed both Incongruent (conflict) and Congruent (nonconflict) trials (see Supplement 1 for detailed task description).

Reaction Time Analyses

Analyses revealed main effects of Stroop wordtype [F(1,26) = 65.09, p < .001] as well as an interaction between group, trial-to-trial adjustment and wordtype [F(1,26) = 4.04, p = .05]. Analyses revealed that the trial-to-trial adjustment RT effect (cI-iI) differed significantly between the MA abusers and controls [F(1,26) = 6.54; p =.04, Bonferroni corrected for multiple comparisons). Whereas the control subjects showed an RT advantage (13 msec benefit) to conflict trials that were preceded by

Discussion

Reduced right PFC activation, most notably in the right midfrontal cortex (BA6), was observed in MA abusers compared with non-substance-abusing control subjects when contrasting conditions that measured how prior exposure to conflict modulated subsequent behavior. In contrast, no significant group differences were observed in conflict-related activation in the ACC (17, 18, 21). These data provide preliminary evidence that MA abuse is associated with deficits in behavioral regulation associated

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