ABSTRACT: Alcohol dependence is associated with neurocognitive deficits related to neuropathological changes in structure, metabolism, and function of the brain. Impairments of motor functioning in alcoholics have been attributed to well-characterized neuropathological brain abnormalities in cerebellum.
Using functional magnetic resonance imaging (fMRI), we studied in vivo the functional connectivity between cerebellar and cortical brain regions. Participants were 10 uncomplicated chronic alcoholic patients studied after 5 to 7 days of abstinence when signs of withdrawal had abated and 10 matched healthy controls. We focused on regions of prefrontal, frontal, temporal, and parietal cortex that exhibited an fMRI response associated with nondominant hand finger tapping in the patients but not in the controls. We predicted that fronto-cerebellar functional connectivity would be diminished in alcoholics compared with controls.
Functional connectivity in a circuit involving premotor areas (Brodmann Area 6) and Lobule VI of the superior cerebellum was reduced in the patients compared with the controls. Functional connectivity was also reduced in a circuit involving prefrontal cortex (Brodmann Area 9) and Lobule VIII of the inferior cerebellum. Reductions in connectivity were specific to fronto-cerebellar circuits and were not found in other regions examined.
Our findings show a pattern in recently abstinent alcoholic patients of specific deficits in functional connectivity and recruitment of additional brain regions for the performance of a simple finger-tapping task. A small sample, differences in smoking, and a brief abstinence period preclude definitive conclusions, but this pattern of diminished fronto-cerebellar functional connectivity is highly compatible with the characteristic neuropathological lesions documented in alcoholics and may reflect brain dysfunction associated with alcoholism.
Alcoholism Clinical and Experimental Research 11/2011; 36(2):294-301. · 3.34 Impact Factor
ABSTRACT: Chronic alcohol-dependent patients (ALC) exhibit neurocognitive impairments attributed to alcohol-induced fronto-cerebellar damage. Deficits are typically found in complex task performance, whereas simple tasks may not be significantly compromised, perhaps because of little understood compensatory changes.
We compared finger tapping with either hand at externally paced (EP) or maximal self-paced (SP) rates and concomitant brain activation in ten pairs of right-hand dominant, age-, and gender-matched, severe, uncomplicated ALC and normal controls (NC) using functional magnetic resonance imaging (fMRI).
Mean tapping rates were not significantly different in ALC and NC for either task, but SP tapping variances were greater in ALC for both hands. SP tapping was more rapid with dominant hand (DH) than non-dominant hand (NDH) for both groups. EP and SP tapping with the non-dominant hand demonstrated significantly more activation in ALC than NC in the pre and postcentral gyri, inferior frontal gyrus, inferior parietal lobule, and the middle temporal gyrus. Areas activated only by ALC (not at all by NC) during NDH tapping included the inferior frontal gyrus, middle temporal gyrus, and postcentral gyrus. There were no significant group activation differences with DH tapping. No brain regions activated more in NC than ALC. SP tapping in contrast to EP activated fronto-cerebellar networks in NC, including postcentral gyrus, anterior cingulate, and the anterior lobe and vermis of the cerebellum, but only parietal precuneus in ALC.
These findings with NDH finger tapping support previous reports of neurocognitive inefficiencies in ALC. Inferior frontal activation with EP in ALC, but not in NC, suggests engagement of regions needed for planning, organization, and impulse regulation; greater contralateral parietal lobe activation with SP in ALC may reflect right hemispheric impairments in visuospatial performance. Contrasting brain activation during SP and EP suggests that ALC may not have enlisted a fronto-cerebellar network as did NC but rather employed a higher order planning mode by recruiting parietal lobe functions to attain normal mean finger tapping rates. Elucidation of the compensatory neural mechanisms that allow near normal performance by ALC on simple tasks can inform functional rehabilitation of patients in recovery.
Alcoholism Clinical and Experimental Research 04/2010; 34(6):1098-109. · 3.34 Impact Factor
ABSTRACT: Fine and gross motor dysfunction in chronic alcoholic patients is prevalent, but not extensively studied. Brain autopsy studies of brain regions involved in motor movements indicate cerebellum and frontal lobes are particularly sensitive to alcohol-induced damage, in contrast to motor cortex.
Using functional magnetic resonance imaging (fMRI), we compared the pattern of activation of the cerebral cortex and cerebellum during repetitive, self-paced dominant (DH) and nondominant (NDH) index finger tapping in eight uncomplicated alcohol-dependent patients after approximately 2 weeks of abstinence and in nine normal controls.
Whereas alcoholic patients tapped significantly more slowly than normal controls, a greater percentage of pixels were activated in the ipsilateral cortex during DH tapping. Furthermore, alcoholics tapped significantly less efficiently (tapping rate divided by percent pixels activated [weighted by pixel intensity] in a given region of interest [ROI]) than normal controls in every ROI examined while using DH, but only in ipsilateral hemi-cerebellum using NDH. Finally, the alcohol-dependent patients did not demonstrate the greater mean pixel activation, percentage activated pixels, and lesser activation efficiency in the ipsilateral cortex during NDH compared to DH tapping that was observed in the normal control group.
These findings are compatible with motor inefficiency and compensatory alterations of cortical-cerebellar circuits. Further studies are needed to determine whether these deficits recover with prolonged abstinence and how they relate to cognitive inefficiency throughout the clinical course of alcoholism.
Alcoholism Clinical and Experimental Research 05/2003; 27(4):704-11. · 3.34 Impact Factor
ABSTRACT: Proton magnetic resonance spectroscopy may elucidate the molecular underpinnings of alcoholism-associated brain shrinkage and the progression of alcohol dependence.
Using proton magnetic resonance spectroscopy, we determined absolute concentrations of -acetylaspartate (NAA), creatine/phosphocreatine (Cr), and choline (Cho)-containing compounds and -inositol (mI) in the anterior superior cerebellar vermis and frontal lobe white matter in 31 alcoholics and 12 normal controls. All patients were examined within 3 to 5 days of their last drink. Patients who did not relapse were again studied after 3 weeks and 3 months of abstinence by using an on-line repositioning technique that allows reliable localization of volumes of interest (VOIs).
At 3 to 5 days after the last drink, frontal white matter metabolite concentrations were not significantly different from those of normal controls, whereas brain tissue in the VOI was reduced. Cerebellar [NAA] and [Cho] and brain and cerebellar volumes were decreased, but [Cr], [mI], and VOI brain tissue volume were not significantly different. Eight patients relapsed before 3 weeks (ER), 12 relapsed between 3 weeks and 3 months (LR), and 11 did not relapse (NR) during 3 months. Cerebellar [NAA] was reduced only in ER patients, despite the fact that ER patients drank for significantly fewer years and earlier in life than LR or NR patients. After 3 months, in the 11 continuously abstinent patients, cerebellar [NAA] and brain and cerebellar volumes increased; cerebellar [Cho], [Cr], and [mI] and VOI brain tissue did not change significantly.
Decreased [NAA] and [Cho] in cerebellar vermis indicate a unique sensitivity to alcohol-induced brain injury. Cerebellar [NAA] increased with abstinence, but reduced [Cho] persisted beyond 3 months. Further studies are needed to determine whether low cerebellar [NAA] is a risk factor for, or consequence of, malignant, early-onset alcoholism.
Alcoholism Clinical and Experimental Research 10/2002; 26(9):1368-80. · 3.34 Impact Factor