Parietal gray matter volume loss is related to spatial processing deficits in long-term abstinent alcoholic men

Abstract

Background: We previously demonstrated relatively intact cognitive function (with the exception of suggestive evidence for persistent deficits in spatial information processing) in middle-aged long-term abstinent alcoholics (LTAA, abstinent for 6 months or more) compared to age and gender comparable nonalcoholic controls (NAC) (Fein et al., 2006).

Methods: In the current study, we examine cortical gray matter volumes in the same samples to determine whether gray matter volumes in LTAA are consistent with the cognitive results--i.e., exhibiting gray matter volumes comparable to NAC in most brain regions, except for possible indications of persistent shrinkage in the parietal lobe subserving spatial information processing.

Results: We found gray matter shrinkage in LTAA in the parietal lobe consistent with the spatial processing deficits in this same sample. More compelling, in LTAA, the magnitude of parietal gray matter shrinkage was negatively associated with spatial processing domain performance and positively associated with alcohol dose. Gray matter volume deficits were present in the occipital and other cortical tissue, but poorer visuospatial test performance correlated significantly with smaller volumes in the parietal cortex only.

Conclusions: Taken together, the cognitive and structural imaging data provide compelling evidence that chronic alcohol abuse results in shrinkage of the parietal cortex with associated deficits in spatial information processing.

Figure 1

The cerebral lobe definitions used in our analyses. The frontal lobe (blue), parietal lobe (yellow), temporal lobe (red), and occipital lobe (green) are visible from the surface of the brain. The limbic lobe, containing the cingulate gyrus, cannot be seen from this viewpoint.

Figure 2

Comparison of ROI creation techniques in standard MNI space. (a-b) Neighboring ROIs consisting of adjacent Brodmann areas: Orbital frontal cortex (red), dorsolateral prefrontal cortex (green). (c-d) The boundaries of the same ROIs created using a three-voxel dilation in MNI space. Notice the significant overlap between nearby ROIs, which was caused in part by dilation from inferior and superior axial slices. (e-f) Nearest neighbor interpolation captures the cortical sheet while preserving boundaries between neighboring ROIs.

Figure 3

There was no significant correlation between parietal lobe volumes and spatial processing scores within the controls (left), but there was a strong trend within the LTAA (right). The dotted lines represent the 95% confidence interval.

Figure 4

In the LTAA women, there was no relationship between parietal lobe volumes and spatial processing scores. The relationship between spatial processing scores and parietal lobe volumes within the LTAA was entirely carried by men (right). The dotted lines represent the 95% confidence interval.

Figure 5

The LTAA men exhibit a significant negative relationship between average lifetime alcohol dose and parietal lobe volume (left) and total gray matter volumes excluding the parietal lobe (right), where increased alcohol consumption is related to lower gray matter volumes within the parietal lobe and other areas of the brain. This relationship between alcohol and volume was not present within LTAA women or the NAC.