Prefrontal cortical volume reduction associated with frontal cortex function deficit in 6-week abstinent crack-cocaine dependent men

Abstract

Background: This study examined regional cortical volumes in 6-week abstinent men dependent on crack-cocaine only (Cr) or on both crack-cocaine and alcohol (CrA). Our goal was to test the a priori hypothesis of prefrontal cortical volume reduction, along with associated impairments in frontal mediated functions, and to look for differences between the Cr and CrA groups.

Methods: Structural magnetic resonance imaging (MRI) of the brain and neuropsychological assessment were performed on 17 6-week abstinent Cr subjects, 29 six-week abstinent CrA subjects, and 20 normal controls. Cortical volume was quantified in the prefrontal, parietal, temporal and occipital regions.

Results: Cr and CrA subjects showed comparable reductions in prefrontal gray matter volume compared to controls; this reduction was negatively associated with performance impairments in the executive function domain.

Conclusions: Dependence on Cr (with or without concomitant alcohol dependence) was associated with reduced prefrontal cortical volume. Cr dependence with concomitant alcohol dependence was not associated with greater prefrontal volume reductions than Cr dependence alone. The existence of these findings at 6-week abstinence indicates that they are not a result of acute cocaine or alcohol exposure. The association of reduced prefrontal cortical volume with cognitive impairments in frontal cortex mediated abilities suggests that this reduced cerebral volume has functional consequences.

Figures

Fig. 1

Counter-clockwise from the top right: the same mid-ventricular axial MRI slice in the T2-weighted, T1-weighted, PD-weighted, and segmented forms for an abstinent Cr and alcohol dependent subject (age 52). The segmented image shows a moderate amount of white matter signal hyperintensity (white areas).

Fig. 2

The abstinent substance dependent samples had reduced regional gray matter in the prefrontal cortex only, with group membership accounting for 10.0% of the variance (P < 0.01); this is compared to less than 1.6% of the variance for parietal, temporal, and occipital cortices (all P > 0.32).