Elevated myo-inositol in gray matter of recently detoxified but not long-term abstinent alcoholics: a preliminary MR spectroscopy study

BACKGROUND: Individuals in short-term abstinence from chronic alcohol consumption commonly have neuropsychological impairments with parallel abnormalities in brain structure. Stable, long-term sobriety often results in improvements in both brain structure and function, although the mechanisms underlying these changes are currently not well understood. METHODS: To investigate further the neurobiological underpinnings of alcohol-associated brain abnormalities in short-term and long-term abstinence from alcohol, proton magnetic resonance spectroscopy (echo time, 35 msec; repetition time, 1.5 sec) was used to assay metabolites in the anterior centrum semiovale, anterior cingulate gyrus, and right thalamus of two groups of non-Korsakoff alcoholic men, at different stages of abstinence, compared with a control group of alcohol-nonabusing men. Absolute concentrations of N-acetylaspartate, choline, myo-inositol, and creatine were measured in four recently detoxified alcoholics (mean age, 48.7 years; median abstinence, 41.5 days), five long-term abstinent alcoholics (mean age, 45.1 years; median abstinence, 1.7 years), and five nonalcoholic controls (mean age, 45.0 years). RESULTS: Although there were no between-group differences in concentrations of N-acetylaspartate, choline, or creatine, recently detoxified alcoholics had significantly higher myo-inositol in the thalamus, compared with controls and long-term abstinent alcoholics, and significantly higher myo-inositol in the anterior cingulate gyrus, compared with the controls. CONCLUSIONS: Elevations in myo-inositol in recently detoxified alcoholics are compatible with an acute alcohol cytotoxicity model. myo-Inositol is elevated in hyperosmolar states such as hypernatremia, renal failure, and diabetes; alcohol-induced hyperosmolarity may trigger accumulation of myo-inositol to stabilize the intracellular environment. Increases in myo-inositol may also reflect proliferation or activation of glia. The reduction of myo-inositol to control group levels in long-term abstinent alcoholics may reflect osmolar stability in abstinent alcoholics and/or a reduction in glial cell activation.     

Hypoperfusion of the Cerebellum and Aging Effects on Cerebral Cortex Blood Flow in Abstinent Alcoholics: A SPECT Study

BACKGROUND: This study evaluated hypotheses concerning alcoholism, aging, and the relationship between cerebral hypoperfusion and residual deficits in the functioning of cerebellar and neocortical brain systems. METHODS: The participants were 10 healthy abstinent alcoholics (9 men, 1 woman) and 12 nonalcoholic controls (10 men, 2 women) ranging in age from 35 to 67 years. Cerebral blood flow was observed through the use of regionally specific computer-derived quantitative analysis of single photon emission computed tomography (SPECT) perfusion images. Cerebellar perfusion was measured and compared with cerebral cortex perfusion in age-equivalent subgroups of alcoholics and controls (under 55 years; 55 years and over). RESULTS: In abstinent alcoholics under age 55, cerebellar perfusion ratios were significantly reduced compared with the controls. In alcoholics and nonalcoholic controls 55 years old and older, this relationship was reversed, probably as a result of diminished cortical perfusion with aging in the alcoholics and of cerebellar decline in the controls. CONCLUSIONS: The findings support hypotheses that the residual effects of alcoholism include cerebellar brain abnormalities and that aging combined with long-term alcoholism leads to cerebral cortical decline.     

Thinning of the Corpus Callosum in Older Alcoholic Men: A Magnetic Resonance Imaging Study

A brain image averaging technique was applied to three-dimensional magnetic resonance images to identify visually detectable brain volume abnormalities in chronically alcoholic men, compared with healthy control men. This technique, which was based on pixel-by-pixel statistical probability mapping, revealed a dramatic reduction in the area of the corpus callosum in older alcoholics (age 45 years or older), relative to age-matched controls. Subsequent analysis used anatomical landmarks to outline the borders of midsagittal sections of the corpus callosum in a larger group of alcoholics and controls, who spanned the adult age range from 23 to 71 years. This analysis revealed significant reduction, most prominent in the genu and body, of total callosal area in the alcoholic group relative to the control group; the results were the same whether raw area measures or head size plus age adjusted measure were analyzed. Significant thinning of the callosal body in alcoholics is usually attributed to the relatively rare, nutritional-deficient condition, Marchiafava-Bignami disease. However, callosal thinning was present in vivo in chronic alcoholics without clinical symptoms of severe liver disease, amnesia, or alcoholic dementia. These data suggest that chronic alcoholism can be characterized by a continuum of graded brain dysmorphology, rather than classical alcoholic-related subsyndromes, such as Marchiafava-Bignami disease.     

Global–Local Interference is Related to Callosal Compromise in Alcoholism: A Behavior-DTI Association Study

Background: Visuospatial ability is a multifactorial process commonly impaired in chronic alcoholism. Identification of which features of visuospatial processing are affected and which are spared in alcoholism, however, has not been clearly determined. We used a global–local paradigm to assess component processes of visuospatial ability and MR diffusion tensor imaging (DTI) to examine whether alcoholism‐related microstructural degradation of the corpus callosum contributes to disruption of selective lateralized visuospatial and attention processes. Methods: A hierarchical letter paradigm was devised, where large global letters were composed of small local letters. The task required identification of target letters among distractors presented at global, local, both, or neither level. Attention was either selectively directed to global or local levels or divided between levels. Participants were 18 detoxified chronic alcoholics and 22 age‐matched healthy controls. DTI provided quantitative assessment of the integrity of corpus callosal white matter microstructure. Results: Alcoholics generally had longer reaction times than controls but obtained similar accuracy scores. Both groups processed local targets faster than global targets and showed interference from targets at the unattended level. Alcoholics exhibited moderate compromise in selectively attending to the global level when the global stimuli were composed of local targets. Such local interference was less with longer abstinence. Callosal microstructural integrity compromise predicted degree of interference from stimulus incongruency in the alcoholic group. This relationship was not observed for lateral or third ventricular volumes, which are measures of nonspecific cortical volume deficits. Conclusion: Global–local feature perception was generally spared in abstinent chronic alcoholics, but impairments were observed when directing attention to global features and when global and local information interfered at stimulus or response levels. Furthermore, the interference‐callosal integrity relationship in alcoholics indicates that compromised visuospatial functions include those requiring bilateral integration of information.     

Cognitive performance in long-term abstinent alcoholic individuals

BACKGROUND: There are few investigations of the potential recovery of neurocognitive function in chronic alcoholic samples after very-long-term abstinence. The current study examined cognitive abilities in middle-aged (mean age 46.8 years), long-term abstinent alcoholic individuals (LTAA). Twenty-five LTAA men and 23 LTAA women abstinent for an average of 6.7 years were compared with an equal number of gender and age-comparable normal controls (NC). We examined the association of neurocognitive variables with age, duration of abstinence, alcohol use measures, and the density of a family history of problem drinking. METHODS: Long-term abstinent alcoholic individuals and NC underwent comprehensive neuropsychological assessment. Performance was measured in the following 9 domains: abstraction/cognitive flexibility, attention, auditory working memory, immediate memory, delayed memory, psychomotor function, reaction time, spatial processing, and verbal skills. RESULTS: Long-term abstinent alcoholic individuals performed similarly to NC, except for deficits in the spatial processing domain. The spatial processing results must be interpreted with caution because of multiple comparison issues; however, spatial processing deficits are among the impairments most often reported in abstinent alcoholic individuals. None of the cognitive measures were associated with length of abstinence, any alcohol use variable, or family history measure. CONCLUSIONS: Very-long-term abstinence resolves most neurocognitive deficits associated with alcoholism, except for the suggestion of lingering deficits in spatial processing.     

Effects of abstinence from alcohol on the broad phospholipid signal in human brain: an in vivo 31P magnetic resonance spectroscopy study

BACKGROUND: In vivo phosphorus magnetic resonance spectroscopy (31P MRS) at a magnetic field strength of 1.5 T allows measurement of fairly mobile membrane phospholipids in the human brain. We previously showed that subjects who are heavy drinkers had a smaller signal and a shorter transverse relaxation time (T2) of white matter phospholipids than light drinkers, which suggested lower concentrations and molecular mobility of phospholipids in heavy drinkers. The purpose of the present study was to measure if such chronic alcohol-induced white matter tissue changes are persistent in long-term abstinent alcoholics. METHODS: Fourteen abstinent alcoholics (mean age 45 years, seven men and seven women) were studied by localized 31P MRS in the centrum semiovale and were compared with 13 male, alcohol-dependent, heavy drinkers and 23 nondependent light drinkers (17 men, 6 women) of similar age. Methods for measurements of the broad membrane phospholipid signal and its relaxation time were described previously. RESULTS: Phospholipid concentrations and relaxation times in alcoholics abstinent for an average of 31 months were not significantly different from those measured in light drinkers. The contribution of fast and slowly relaxing signal components to the broad phospholipid signal, however, was still different in abstinent alcoholics compared with light drinkers. No effects of sex or of family history of alcoholism were noted on any of our spectroscopic measures within the light-drinking or abstinent groups. CONCLUSIONS: Most of our results suggest at least partial recovery of chronic alcohol-induced white matter phospholipid damage with long-term abstinence. They offer myelination changes and/or dendritic rearborization as a possible mechanism for the commonly observed white matter volume gain with prolonged abstinence. But the results also suggest a persistent abnormality in the nature and/or physical properties of white matter phospholipids in long-term abstinent alcoholics.     

Mammillary Body and Cerebellar Shrinkage in Chronic Alcoholics with and without Amnesia

Mammillary body and cerebellar atrophy have been described as postmortem neuropathologic markers of Korsakoff's syndrome. This study examined whether shrinkage in the mammillary bodies and cerebellum is present consistently in amnesic chronic alcoholics during lie and whether the degree of abnormality in these patients differs from that in nonamnesic alcoholics and healthy controls. The severity of shrinkage in the mammillary bodies, cerebellar hemispheres, and cerebellar vermis visualizable on MRI scans was rated on a three-point scale in 33 chronic nonamnesic alcoholics, 9 amnesic alcoholics, and 20 healthy controls. Although both alcoholic groups showed significant mammillary body and cerebellar shrinkage relative to controls, the two patient groups did not differ from each other. Furthermore, four of eight amnesic patients in our sample did not demonstrate clinically significant mammillary body atrophy. These results suggest that alcoholism is associated with mammillary body and cerebellar tissue volume loss but do not provide evidence that these markers distinguish accurately between amnesic and nonamnesic patients. In addition, they suggest that visualizable mammillary body atrophy is not necessary for the development of amnesia in alcoholic patients.     

Frontal Lobe Volume Loss Observed with Magnetic Resonance Imaging in Older Chronic Alcoholics

This study used magnetic resonance imaging to quantify the extent and pattern of tissue volume deficit and cerebrospinal fluid volume enlargement in younger versus older chronic alcoholics relative to normal controls. In the present analysis, we divided our previously reported group of 62 alcoholic men into a younger group (n = 33, age mean = 37.5 ± 4.5, and range = 26 to 44 years) and an older group ( n = 29, age mean = 52.7 ± 6.0, and range = 45 to 63 years) to examine whether, in addition to extent, the two age groups differed in pattern of tissue type and regional brain volume abnormalities quantified with magnetic resonance imaging. Brain volumes were adjusted for normal variation in head size and age established from a group of healthy controls and were expressed as Z-scores. The younger group had significant cortical gray, but not white, matter volume deficits and sulcal and ventricular enlargement relative to age-matched controls. The older group had volume deficits in both cortical gray and white matter and sulcal and ventricular enlargement that significantly exceeded the younger alcoholic group. An analysis of six cortical regions revealed that, although both age groups had gray matter volume deficits throughout the cortex, the older alcoholic group had a selectively more severe deficit in prefrontal gray matter relative to the younger alcoholic group. Similarly, the cortical white matter volume deficit in the older alcoholics was especially severe in the prefrontal and frontal regions. The differences in brain dysmorphology between the two alcoholic groups cannot easily be attributed to potential alcohol history differences typically related to age because the two groups had similar disease durations and amounts of lifetime alcohol consumption. These results provide in vivo evidence that the frontal lobes are especially vulnerable to chronic alcoholism in older men.     

Auditory Brainstem Potentials in Sons of Alcoholic Fathers

With the use of event-related brain potentials we have observed sensory as well as cognitive deficits in abstinent alcoholics. By recording auditory brainstem potentials (BSP) from abstinent alcoholics we demonstrated significant delays in brainstem transmission time. We have also reported that P3 amplitudes are significantly reduced in abstinent alcoholics compared to control subjects. Although the neurophysiological deficits observed in abstinent alcoholics are presumed to be alcohol-related effects, it is possible that some of these deficits may exist prior to alcohol exposure, and may be present in subjects at high risk for alcoholism. We have recently observed significantly reduced P3 components in young sons of alcoholics similar to those observed in abstinent alcoholics. In the present study, we examined auditory BSPs in young boys at high risk for alcoholism and matched controls. We found no statistically significant difference in brainstem transmission time between high risk individuals and matched control subjects. These findings suggest that while some brain deficits observed in abstinent alcoholics may antecede the development of alcoholism (P3) and may represent a predisposing factor, other deficits (BSP) appear to be the consequence of alcohol and/or nutritional-related effects.     

Essential Fatty Acid Supplementation during Early Alcohol Abstinence

Interactions between ethanol, prostaglandins, and essential fatty acids (EFA) have led to the hypothesis that acute alcohol withdrawal and the sequelae of chronic alcoholism may be related to an EFA/prostaglandin deficiency. To test this hypothesis, EFA profiles in blood-lipid fractions, serum liver enzymes, cognitive function, and alcohol craving were measured in 27 acutely abstinent alcoholics before and after a 3-week double-blind trial of EFA supplementation. Upon entry into the study, alcoholics had significant differences in EFA levels as compared to normal controls, and serum levels of liver enzymes tended to correlate with these EFA levels. After 21 days, cognitive function, alcohol craving, and liver enzymes all improved in both the EFA and placebo groups; most EFA levels also approached normal values. There were no treatment effects of EFA supplementation at the dose used.     

The neuropsychological consequences of abstinence among older alcoholics: a cross-sectional study

BACKGROUND: The older alcoholic has been distinguished from the younger alcoholic with regard to both the acute effects of alcohol and also the recovery of functioning with abstinence. Few studies, however, have included samples of exclusively older subjects. In this investigation we examined the recovery of functioning in an older cohort of recovering alcoholics (age range 55-83) to determine which neuropsychological functions improve and which remain impaired with abstinence. METHODS: We used a cross-sectional design, comparing three demographically matched groups on a battery of neuropsychological tests: (a) older alcoholics who had been abstinent for greater than 6 months, (b) older alcoholics who had been abstinent for less than 6 months, and (c) a control group of older subjects without alcohol abuse histories. RESULTS: In almost all tasks, the alcoholics who were abstinent for less than 6 months performed worse than the control group. In contrast, the alcoholics who had been abstinent for more than 6 months differed from the control group on learning and recall of a word list, immediate and delayed recall of a complex figure, initial letter fluency, and clock drawing. CONCLUSIONS: Memory and executive skills appear to be resistant to recovery or at least slower to recover with abstinence in the older alcoholic. The impairment with visuospatial skills reported in prior investigations of alcoholics may be related to compromised executive functions, which interfere with the encoding of more complex visuospatial information and thus affect recall of such information. Studies that involve larger samples of older alcoholics are needed to understand their ability to recover cognitive functioning with abstinence.     

Mismatch negativity: no difference between controls and abstinent alcoholics

BACKGROUND: A number of studies have examined the amplitude of the mismatch negativity (MMN) evoked potential as a measure of a brain inhibitory deficit in alcoholics or those at risk for alcoholism. The current study examined MMN in alcoholics abstinent an average of 6.7 years (with a minimum of six months abstinence) compared to controls. This study examined the association of MMN with alcoholism family history density, with indices of the presence and severity of externalizing disorders (a risk-factor for alcoholism), and with alcohol use variables. METHODS: Electroencephalograms were gathered on 76 subjects (38 controls, 38 abstinent alcoholics) during a nonattending mismatch negativity experiment. Measures of alcoholism family history density, disinhibited personality traits, and antisocial symptoms served as measures of risk-factors known to be associated with a genetic liability to alcoholism. Alcohol use variables were used as measures of alcoholism severity. RESULTS: There were no differences in MMN amplitude or latency between controls and abstinent alcoholics. There also were no significant associations between MMN measures and the measures of risk for alcoholism or with the severity of alcohol use or duration of abstinence. CONCLUSIONS: The results suggest that MMN is neither affected in chronic alcoholics nor associated with alcoholism vulnerability, and thus does not reflect a trait marker of alcoholism or alcoholism risk. The current results do not address effects on MMN of acute alcohol ingestion or withdrawal from alcohol.     

Temporal discrimination learning in abstinent chronic alcoholics

BACKGROUND: Converging evidence from varied experimental paradigms has demonstrated that the cerebellum is involved in the timing of learned behavior. Given the documented neurological changes secondary to chronic alcoholism, particularly cerebellar degeneration, the ability of recovered chronic alcoholics to learn a temporal discrimination was assessed by using delayed eyeblink classical conditioning. METHODS: Twelve abstinent alcoholic participants and 12 matched control participants were randomly presented 2 clearly discriminable tone conditioned stimuli that were individually paired with 2 different interstimulus intervals. RESULTS: The data revealed a significant alteration in the abstinent alcoholics' peak latency measure at the long interstimulus intervals and an overall impairment in their level of acquisition of conditioned responses. No group differences in extinction were observed. CONCLUSIONS: It was speculated that cerebellar cortical atrophy caused by years of alcohol abuse resulted in the peak latency alteration and that atrophy extending into deep cerebellar nuclei caused the overall impairment in conditioned response acquisition.     

Brain and Liver Dolichol in Chronic Alcoholism: A Necropsy Study

Cerebral gray and white matter and liver dolichol levels were measured in postmortem samples from chronic alcoholics and nonalcoholic controls following recent suggestions that dolichol levels may be used as a marker for alcoholism. No significant differences in brain dolichol were found between the control and alcoholic groups. A significant reduction in the liver dolichol was observed in the alcoholic group. This was most marked in those alcoholics with liver disease.     

Quantitative brain MRI in alcohol dependence: preliminary evidence for effects of concurrent chronic cigarette smoking on regional brain volumes

BACKGROUND: Recent in vivo research using magnetic resonance spectroscopy demonstrated that chronic cigarette smoking exacerbates regional chronic alcohol-induced brain injury. Other studies associated cigarette smoking with gray matter volume reductions in healthy adults, with greater brain atrophy in aging, and with poorer neurocognition. Although cigarette smoking is common among alcohol-dependent individuals, previous research did not account for the potential effects of chronic smoking on regional brain volumes in alcoholism. METHODS: High-resolution T1-weighted magnetic resonance images from one-week-abstinent, alcohol-dependent individuals and light drinkers were automatically segmented into gray matter, white matter, and cerebral spinal fluid of lobes and subcortical structures. A brief neuropsychological test battery was used to assess cognition in alcohol-dependent individuals. The alcoholic and nondrinking groups were retrospectively divided into chronic smokers and nonsmokers, and the volumetric data were analyzed as a function of alcohol and smoking status. RESULTS: Chronic alcohol dependence was associated with smaller volumes of frontal and parietal white matter, parietal and temporal gray matter, and thalami, accompanied by widespread sulcal but not ventricular enlargements. Chronic cigarette smoking was associated with less parietal and temporal gray matter and with more temporal white matter. Among alcoholics, better visuospatial learning and memory and greater visuomotor scanning speed were correlated with larger lobar white matter volumes in the nonsmoking alcohol-dependent group only. CONCLUSIONS: These data provide preliminary evidence that comorbid chronic cigarette smoking accounts for some of the variance associated with cortical gray matter loss and appears to alter relationships between brain structure and cognitive functions in alcohol-dependent individuals.     

Age and Alcoholism: Independent Memory Decrements

Similarities and differences in performances on 18 verbal and nonverbal memory tasks were studied in young and old alcoholics and in young and old controls as test of hypotheses postulating that cognitive decrements from alcoholism either mimic "premature aging," are "age sensitive," or are "independent" from those of normal aging. Young and old alcoholics were matched in length and rate of heavy drinking and were also equated with their controls in age, education, and vocabulary. The multivariate memory and decision data, when converted to independent factor scores, separated alcoholic from control groups on a factor reflecting memory for auditorily presented information. This was independent from factor scores affected mainly by age, such as memory for visuospatial items or decision bias. Age and alcoholism produced overlapping but distinctly different profiles of memory impairments. Decrements in young alcoholics did not resemble those of aging nor did old alcoholics surpass old controls in any but one factor, so that neither the premature aging nor the age sensitivity hypothesis were invariably supported.     

Reduced fronto-cerebellar functional connectivity in chronic alcoholic patients

Background: 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. Methods: 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. Results: 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. Conclusions: 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.     

Growth Hormone, Vasopressin, Cortisol, and Catecholamine Responses to Insulin Hypoglycemia in Alcoholics

The hormonal responses to insulin-induced hypoglycemia were studied in 15 abstinent alcoholics with varying degrees of central and peripheral nerve damage and in six normal controls. Blood samples were taken at intervals after the injection of soluble insulin (0.1 U/kg of body weight). Growth hormone responses were significantly depressed (p less than 0.05) in nine alcoholics with severe central nerve damage (Korsakoff's psychosis) as compared to other alcoholic subjects. The alcoholic subjects with Korsakoff's psychosis also showed significant depression (p less than 0.01) of glucose recovery from hypoglycemia as compared with controls. However, responses of vasopressin, cortisol, and catecholamines (epinephrine and norepinephrine) were generally normal in the Korsakoff patients. Our results do not support previous suggestions that impairment of memory in alcoholism may be related to altered vasopressin secretion, even though the reduced growth hormone secretion in brain-damaged alcoholics does indicate some hypothalamic-pituitary dysfunction.     

Brain fMRI activation associated with self-paced finger tapping in chronic alcohol-dependent patients

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.