Learning in young alcoholics

Visuoperceptive Impairments in Severe Alcohol Use Disorder: A Critical Review of Behavioral Studies

The present literature review is aimed at offering a comprehensive and critical view of behavioral data collected during the past seventy years concerning visuoperception in severe alcohol use disorders (AUD). To pave the way for a renewal of research and clinical approaches in this very little understood field, this paper (1) provides a critical review of previous behavioral studies exploring visuoperceptive processing in severe AUD, (2) identifies the alcohol-related parameters and demographic factors that influence the deficits, and (3) addresses the limitations of this literature and their implications for current clinical strategies. By doing so, this review highlights the presence of visuoperceptive deficits but also shows how the lack of in-depth studies exploring the visual system in this clinical population results in the current absence of integration of these deficits in the dominant models of vision. Given the predominance of vision in everyday life, we stress the need to better delineate the extent, the specificity, and the actual implications of the deficits for severe AUD.

Exploring What the Austin Maze Measures: A Comparison Across Conventional and Computer Versions

The Austin Maze is a neuropsychological assessment tool used to measure cognitive function. A computerised version of the tool has recently been developed and shown to be equivalent to the conventional version in terms of performance. However, controversy remains regarding which specific cognitive constructs the conventional and computer versions of the Austin Maze purport to measure. The aim of this study was to investigate which cognitive constructs are associated with Austin Maze performance and whether these constructs remain equivalent across conventional and computer versions. Sixty-three healthy people completed both conventional and computerised versions of the Austin Maze in addition to a number of established measures of planning, error utilisation, working memory, visuospatial ability and visuospatial memory. Results from a series of regression analyses demonstrated that both versions of the Austin Maze were predominantly associated with visuospatial ability and visuospatial memory. No executive measures, including those of planning, error utilisation or working memory, significantly contributed to any Austin Maze performances. This study complements previous research and supports equivalency of the conventional and computer versions of the Austin Maze.

Subcortical volumes are reduced in short-term and long-term abstinent alcoholics but not those with a comorbid stimulant disorder

Chronic alcohol abuse affects brain structure and function. We examined subcortical structure volumes in 77 short (6–15 week) and 90 long (multi-year) term abstinent alcoholics, along with 74 controls. We used a 3T Siemens MPRAGE sequence for image acquisition and FSL FIRST software for measuring subcortical volumes. When examining alcoholics without a comorbid stimulant disorder we found reduced hippocampal, pallidum and thalamus volumes in short term abstinence compared to a non-substance abusing control sample with numerically smaller yet still significant reductions compared to controls in long term abstinence. When examining alcoholics with a comorbid stimulant disorder, no difference from controls was found for any subcortical volume. Alcoholics with a stimulant disorder had significantly larger subcortical volumes than alcoholics without a stimulant disorder.

This study replicates past research showing that chronic alcohol abuse is associated with lower subcortical volumes in short-term abstinent chronic alcoholics and extends this finding, although with smaller effects to long-term abstinent samples. The absence of this effect in the presence of a comorbid stimulant disorder suggests either a protective effect of stimulant abuse/dependence or that the measurements reflect the aggregate of alcohol dependence associated atrophy and stimulant abuse associated inflammation. Associations with function suggest the second of these two alternatives.

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Subcortical atrophy

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Chronic alcohol dependence

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Comorbid stimulant disorder

Comparing Performance of Young Adults on a Computer-based Version of the Austin Maze and the Conventional Form of the Test

The Austin Maze has declined in use in both clinical and research contexts due to difficulties in accessing the conventional button-box form of the test. Computer-based versions of the Austin Maze offer a potential means of making the test more accessible, but as yet there is limited evidence regarding the equivalence of computer and conventional versions of the Austin Maze. The present study compared performance on a computer version of the Austin Maze by Bray and McDonald with performance on the traditional button maze in 63 participants aged 18–27 years. The results showed no differences between the computer and conventional versions in terms of mean scores and distributions, and performances on the two versions were significantly correlated. Examination of correlates found no relationship between Austin Maze performance and years of education or age for either version of the Austin Maze performance. Intellectual function was modestly associated with performance on the conventional version but not the computer version. Overall, these findings suggest that scores on the Bray and McDonald computer version of the Austin Maze produces comparable scores to the conventional form of the test and can be interpreted using existing normative data.

Subcortical volumes in long-term abstinent alcoholics: associations with psychiatric comorbidity

BACKGROUND

Research in chronic alcoholics on memory, decision-making, learning, stress, and reward circuitry has increasingly highlighted the importance of subcortical brain structures. In addition, epidemiological studies have established the pervasiveness of co-occurring psychiatric diagnoses in alcoholism. Subcortical structures have been implicated in externalizing pathology, including alcohol dependence, and in dysregulated stress and reward circuitry in anxiety and mood disorders and alcohol dependence. Most studies have focused on active or recently detoxified alcoholics, while subcortical structures in long-term abstinent alcoholics (LTAA) have remained relatively uninvestigated.

METHODS

Structural MRI was used to compare volumes of 8 subcortical structures (lateral ventricles, thalamus, caudate, putamen, pallidum, hippocampus, amygdala, and nucleus accumbens) in 24 female and 28 male LTAA (mean abstinence=6.3 years, mean age= 46.6 years) and 23 female and 25 male nonalcoholic controls (NAC) (mean age=45.6 years) to explore relations between subcortical brain volumes and alcohol use measures in LTAA and relations between subcortical volumes and psychiatric diagnoses and symptom counts in LTAA and NAC.

RESULTS

We found minimal differences between LTAA and NAC in subcortical volumes. However, in LTAA, but not NAC, volumes of targeted subcortical structures were smaller in individuals with versus without comorbid lifetime or current psychiatric diagnoses, independent of lifetime alcohol consumption.

CONCLUSIONS

Our finding of minimal differences in subcortical volumes between LTAA and NAC is consistent with LTAA never having had volume deficits in these regions. However, given that imaging studies have frequently reported smaller subcortical volumes in active and recently detoxified alcoholics compared to controls, our results are also consistent with the recovery of subcortical volumes with sustained abstinence. The finding of persistent smaller subcortical volumes in LTAA, but not NAC, with comorbid psychiatric diagnoses, suggests that the smaller volumes are a result of the combined effects of chronic alcohol dependence and psychiatric morbidity and suggests that a comorbid psychiatric disorder (even if not current) interferes with the recovery of subcortical volumes.

Effect of ecstasy use on neuropsychological function: a study in Hong Kong

RATIONALE

Previous studies on the effects of ecstasy on neuropsychological performance have often recruited small sample sizes.

OBJECTIVES

The present study was conducted to validate previous findings regarding the effects of ecstasy consumption on neuropsychological performance.

METHOD

A comprehensive neuropsychological investigation was conducted in 100 abstinent ecstasy users and 100 matched non-user counterparts on standardized measures of working memory, verbal and non-verbal memory, verbal and figural fluency, and selective and switching attention.

RESULTS

Abstinent ecstasy users were impaired on verbal and non-verbal memory, complex attention, and verbal fluency, but not on working memory, relative to their non-user counterparts. Of particular interest was the fact that abstinent ecstasy users performed better on figural fluency relative to their non-user counterparts. In addition, only cumulative ecstasy consumption correlated with neuropsychological performances among abstinent ecstasy users. Canonical discriminant analysis yielded verbal and visual memory, switching attention, and verbal fluency as potential core neuropsychological variables for differentiating abstinent ecstasy users from non-users. Levels of depression and general non-verbal intelligence, as measured by the Beck Depression Inventory and the test of non-verbal Intelligence, respectively, were not likely to affect these findings, since these measures were matched between ecstasy users and non-users.

CONCLUSIONS

These findings suggest that previous ecstasy consumption can affect a wide range of neuropsychological performance, though figural fluency may be subsequently enhanced as a result of the phenomenon of "cortical disinhibition." Furthermore, measures of verbal and visual memory, switching attention, and verbal fluency may be particularly useful for differentiating abstinent ecstasy users from non-users.

Normative verbal and non-verbal memory test scores for Australian women aged 56-67

OBJECTIVE

To establish normative data for tests of verbal and non-verbal memory for midlife Australian-born women, and in so doing investigate factors which contribute to variation in test performance.

METHOD

Two hundred and fifty-seven healthy women aged 56-67 years (mean age 60), who are participating in the Melbourne Women's Midlife Longitudinal Health Project, were administered two word list learning tasks, a story recall task (the East Boston Memory Test) and the Faces subtest from the Wechsler Memory Scale III as part of a larger neuropsychological battery. Word list learning tasks consisted of either 16 semantically related words, derived from the California Verbal Learning Test II, or a list of 10 unrelated words. Mood was assessed by the Center for Epidemiological Studies Depression questionnaire.

RESULTS

Education was significantly related to memory performance and there was a non-significant trend for test scores to decline with age. Mood was unrelated to test performance. A confirmatory factor analysis indicated a clear distinction between verbal and non-verbal memory performances. Mean scores were stratified by education (less than 12 years vs. 12 or more years) and age (56-59 vs. 60-67 years), and scaled normative data were constructed for all the tests.

CONCLUSION

This study provides education-based normative data for tests of verbal and non-verbal memory for midlife Australian women. The establishment of population-based normative data will facilitate future investigations of ageing and dementia in Australian women.

An Exploratory Study of the Use of the Austin Maze in South Africa

A software version of the Austin Maze together with the Halstead-Reitan Category Test and Raven's Standard Progressive Matrices were administered to 30 students at the University of Venda, South Africa. For the entire sample, the average number of trials taken to reach criterion (that is, three consecutive error-free trials) on the Austin Maze was 19. The performance of male subjects was generally better than that of females. No significant correlations were found between performance on the Austin Maze and scores on the other psychometric tests. This is seen as implying that, for this group of subjects, the Austin Maze measures a different construct, as documented in the literature. The complexity of a contextual interpretation of the subjects poorer performance on the measures is discussed.

Effects of prolonged ethanol exposure on neurophysiological measures during an associative learning paradigm

Long-term ethanol exposure has been reported to produce electrophysiological and cognitive impairments in some alcoholics. This study assessed the effects of chronic ethanol exposure on neurophysiological indices of associative learning in rats. Male Wistar rats (46) were exposed to ethanol vapor (EtOH group) or air (control group) for 6 consecutive weeks. After the animals were withdrawn from ethanol, electrodes were implanted in the frontal and parietal cortices and in the amygdala. Following a prolonged abstinence from ethanol (10-15 weeks), rats were exposed to a classical conditioning paradigm in which a food pellet was paired with the presentation of an auditory stimulus. During the first five sessions (conditioning phase), food pellet presentation was paired with the presentation of an infrequently presented tone. During the second five sessions (extinction phase), the association between food pellet presentation and the infrequently presented tone was weakened by no longer presenting food pellets following the infrequent tone. During selected test sessions, event-related brain potentials (ERPs) elicited by each tone (i.e. food-paired tone, non-paired tone) were recorded and analyzed. These analyses revealed differences in ERP responses between the groups. The latency of the N1 and P2 ERP components in the cortex of the control group, but not the EtOH group, increased during sessions when the association between food pellet delivery and tone presentation was being established or extinguished. These data support the hypothesis that chronic ethanol treatment results in a loss of responsivity in ERP components sensitive to changes in food-tone associations, even following a prolonged period of withdrawal from ethanol.

Long-term abstinent alcoholics have normal memory

It is generally believed that many non-Korsakoff alcoholics have subtle defects in memory. To determine whether such defects vary as a function of length of abstinence (LOA), we performed extensive memory testing with: (1) recently detoxified (n = 31; LOA-29 days); (2) intermediate-term abstinent (n = 28; LOA = 1.9 years); (3) long-term abstinent (n = 32; LOA-7.0 years) alcoholics; and (4) nonalcoholic controls (n = 37). All subjects were matched on age and education. Alcoholics were matched on years of alcoholic drinking. Memory measures were divided into the following domains: verbal learning, verbal recall, visual learning, visual recall, and paired associate learning. A series of MANOVAs were conducted that revealed a significant relationship between visual learning and length of abstinence, and a significant interaction between age and length of abstinence on visual recall. Long-term abstinent subjects were not significantly different from controls on any test. We conclude that memory disturbance demonstrable among recently detoxified alcoholics in the early weeks of their abstinence is not evident in demographically matched long-term abstinent alcoholics with similar drinking histories.

Cognitive functioning in excessive drinkers: evidence for dissociable impairments

This article reviews the evidence for neuropsychological impairments in excessive drinkers. The view that the neuropsychological impairments reflect clinically heterogeneous manifestations of a unitary 'Wernicke-Korsakoff complex' resulting from thiamine deficiency is discounted on the basis of a variety of mediating factors which have been demonstrated to affect the pattern of cognitive abilities and deficits in excessive drinkers. In contrast, this article argues that detailed analysis of the apparent clinical heterogeneity in the cognitive status of these patients may provide a means for determining the most appropriate treatment regime and rehabilitation procedures for an individual. These impairments are applied to a theoretical model of information processing identifying dissociable impairments which have been described as the 'frontal-lobe' and the 'right hemisphere' hypotheses of the effects of alcohol on cognitive functioning. Interpretation of research results in terms of functional characteristics rather than localization characteristics is proposed. Two mediating factors, thiamine deficiency and liver dysfunction, are discussed in relation to their differential involvement in these impairments.

Drinking and cognitive impairment: current concepts and controversies

The study of drinking and cognitive impairment has been very popular. Over the past 15 years much work has been conducted examining the specific characteristics of alcohol-related impairment, concurrent morphological changes and the process itself. Numerous theories have been advanced and progress has been made in a number of areas. However, at the present time the area is undergoing a period of re-evaluation. it is clear that if there is an association between alcohol consumption and cognitive impairment, there are a multitude of 'other factors' which need to be controlled for, before one can maintain that observed impairment is indeed a result of alcohol consumed.

Effect of social drinking on neuropsychological performance

The effects of social drinking on neuropsychological function have been assessed in a group of healthy male volunteers. Subjects were divided into three groups according to their daily alcohol consumption: (1) 40 g or less (n = 93), (2) 41-80 g (n = 22), (3) 81-130 g (n = 16). Group 1 had been drinking at the present level for a mean of 12.6 years, group 2 for 16.9 years and group 3 for 15.1 years; the differences are not significant. There are no significant differences on any neuropsychological tests variables between groups 1 and 2. However, subjects in group 3 were found to perform at a significantly lower level than groups 1 and 2 on the Rey Auditory Verbal Learning Test, the Austin Maze, and the Little Man and Spatial Memory Tests of the Bexley Maudsley Automated Psychological Screening Test. The pattern of deficits found in heavy social drinkers is less severe but otherwise similar to that found in alcoholics.