Enlarged striatum in abstinent methamphetamine abusers: a possible compensatory response

Abstract

Background: Little is known about structural brain abnormalities associated with methamphetamine (METH) abuse; therefore, we aimed: 1) to evaluate possible morphometric changes, especially in the striatum of recently abstinent METH-dependent subjects; 2) to evaluate whether morphometric changes are related to cognitive performance; and 3) to determine whether there are sex-by-METH interactions on morphometry.

Methods: Structural MRI was performed in 50 METH and 50 comparison subjects with the same age range and sex proportion; quantitative morphometric analyses were performed in the subcortical gray matter, cerebellum and corpus callosum. Neuropsychological tests were also performed in 44 METH and 28 comparison subjects.

Results: METH users showed enlarged putamen (left: + 10.3%, p = .0007; right: + 9.6%, p = .001) and globus pallidus (left: + 9.3%, p = .002; right: + 6.6%, p = .01). Female METH subjects additionally showed larger mid-posterior corpus callosum (+ 9.7%, p = .05). Although METH users had normal cognitive function, those with smaller striatal structures had poorer cognitive performance and greater cumulative METH usage.

Conclusions: Since METH subjects with larger striatal structures had relatively normal cognitive performance and lesser cumulative METH usage, the enlarged putamen and globus pallidus might represent a compensatory response to maintain function. Possible mechanisms for the striatal enlargement include glial activation and inflammatory changes associated with METH-induced injury.

Figure 1

Left: Axial MRI slices showing brain regions measured in the current study. Right: Bar graphs showing larger lentiform nuclei (putamen and globus pallidus) in the METH users compared to non-drug users. MRI, magnetic resonance imaging; METH, methamphetamine.

Figure 2

Left: Sagittal MRI showing the 4 sectors of the corpus callosum measured. Right: Bar graphs showing sex-by-region interaction in the CC3 portion of the corpus callosum. MRI, magnetic resonance imaging.

Figure 3

Correlations between cognitive function and striatal structures in the METH users. Smaller putamen and globus pallidus, averaged between left and right, are associated with poorer performance. Solid lines in graph indicate mean values from male control subjects while dotted lines indicated mean values from female subjects. METH, methamphetamine.

Figure 4

Correlations between cumulative METH usage and volumes of putamen and globus pallidus in METH users. Solid line indicates male METH users and dotted line indicates female METH users. Correlation values are for both male and female METH users. METH, methamphetamine.