Brain atrophy and intellectual impairment in heavy drinkers--a clinical, psychometric and computerized tomography study

Photoacoustic imaging for in vivo quantification of alcohol-induced structural and functional changes in cerebral vasculature in high alcohol-preferring mice (HAP)

Alcohol-induced structural and functional changes were studied in vivo by photoacoustic tomography (PAT) of the cerebrovascular system in selectively bred alcohol-preferring mice. High (HAP) and low (LAP) alcohol-preferring mice are replicate lines of mice selectively bred to prefer 10% (v/v) ethanol to water and water to ethanol, respectively, in a free-access two-bottle choice scenario. A cohort of 15 singly-housed alcohol-preferring mice (five HAP mice for the experimental group, five LAP mice for the control group, and five other LAP mice set aside) were given free-access two-bottle choice 10% ethanol (v/v) and water in 50-mL graduated drinking bottles mounted on each of their cages for 4 weeks prior to PAT brain scanning. A daily log of the volume of ethanol consumed over a 24-h period was kept. At the end of the fourth week, blood samples were collected from the HAP mice and blood ethanol concentrations (BECs) were measured to ascertain their levels of ethanol intoxication. The mice were then grouped into five weight-matched pairs of HAP and LAP for comparison purposes, and noninvasive in vivo PAT imaging was performed on each weight-matched pair. To mimic a binge drinking paradigm, mice were rearranged into four weight-matched groups of three animals each: an HAP mouse and two LAP mice. For each group, one HAP mouse and one LAP mouse received a 20% ethanol solution via intraperitoneal (i.p.) injection after 24 h of ethanol abstinence, in weight-based doses of 3 g/kg prior to imaging, while the last LAP mouse received a sham i.p. injection. PAT images of the brain were collected for 30 min thereafter. Cerebral vascular diameters for selected vessels of interest were extracted from the PAT images and compared between HAP mice and LAP mice. For the binge scenario, changes in vessel diameter and hemoglobin oxygen saturation were extracted from PAT images and studied over a 30-min duration. Vascular diameter was significantly smaller in HAP mice compared to LAP mice in weight-matched pairs. Hemoglobin-oxygen saturation and vessel diameter dropped more quickly in LAP mice than in HAP mice following a 20% ethanol i.p. injection (3 g/kg), with a 32% reduction in cerebrovascular diameter in a 30-min period. This study demonstrates the effectiveness of PAT in alcohol addiction imaging and diagnosis, and its feasibility in studying alcohol-induced changes in vascular structure and perfusion. It also adds to other bodies of evidence to suggest that the effects of binge drinking are more adverse in occasional drinkers than habitual drinkers.

Apolipoprotein E4 exacerbates ethanol-induced neurotoxicity through augmentation of oxidative stress and apoptosis in N2a-APP cells

Neuronal loss is a prominent phenomenon in Alzheimer's disease (AD) and alcohol-induced brain damage. Alcohol abuse is associated with an increased risk of AD, regardless of the type of alcoholic beverage. Furthermore, the detrimental effect of excessive alcohol consumption on the risk of AD is exacerbated among people carrying apolipoprotein E (APOE) ε4 allele, the major genetic risk factor for AD. However, how APOE ε4 and alcohol abuse synergistically enhance the possibility of AD is unclear. Here we show that in N2a cells stably expressing human APP695 (N2a-APP), high-concentration ethanol-induced neurotoxicity was significantly augmented in the presence of apoE4 protein, compared with apoE3 protein. Early and late apoptotic cells were apparently more in cells treated with the combination of apoE4 and ethanol, compared with that of apoE3 and ethanol. Inhibition of apoptosis using a pan-caspase inhibitor z-vad resulted in abolishment of the apoE isoform-specific effect on high-concentration ethanol-induced neurotoxicity. Moreover, compared with apoE3, apoE4 augmented ethanol-induced cellular oxidative stress, and pre-incubation with a reactive oxygen species (ROS) scavenger NAC abrogated the specific effect of apoE4 on ethanol-induced neurotoxicity. Taken together, our results for the first time demonstrate that apoE4 and high-concentration ethanol synergistically enhance neurotoxicity through elevating cellular oxidative stress and increasing neuronal apoptosis, and support the notion that avoiding excessive alcohol consumption can help to prevent AD especially in APOE ε4 carriers.

Alcohol use across the lifespan: An analysis of adolescent and aged rodents and humans

Adolescence and old age are unique periods of the lifespan characterized by differential sensitivity to the effects of alcohol. Adolescents and the elderly appear to be more vulnerable to many of alcohol's physiological and behavioral effects compared to adults. The current review explores the differential effects of acute alcohol, predominantly in terms of motor function and cognition, in adolescent and aged humans and rodents. Adolescents are less sensitive to the sedative-hypnotic, anxiolytic, and motor-impairing effects of acute alcohol, but research results are less consistent as it relates to alcohol's effects on cognition. Specifically, previous research has shown adolescents to be more, less, and similarly sensitive to alcohol-induced cognitive deficits compared to adults. These equivocal findings suggest that learning acquisition may be differentially affected by ethanol compared to memory, or that ethanol-induced cognitive deficits are task-dependent. Older rodents appear to be particularly vulnerable to the motor- and cognitive-impairing effects of acute alcohol relative to younger adults. Given that alcohol consumption and abuse is prevalent throughout the lifespan, it is important to recognize age-related differences in response to acute and long-term alcohol. Unfortunately, diagnostic measures and treatment options for alcohol dependence are rarely dedicated to adolescent and aging populations. As discussed, although much scientific advancement has been made regarding the differential effects of alcohol between adolescents and adults, research with the aged is underrepresented. Future researchers should be aware that adolescents and the aged are uniquely affected by alcohol and should continue to investigate alcohol's effects at different stages of maturation.

Assessment of abstract reasoning abilities in alcohol-dependent subjects: an fMRI study

INTRODUCTION

Chronic alcohol abuse has been traditionally associated with impaired cognitive abilities. The deficits are most evident in higher order cognitive functions, such as abstract reasoning, problem solving and visuospatial processing. The present study sought to increase current understanding of the neuropsychological basis of poor abstract reasoning abilities in alcohol-dependent subjects using functional magnetic resonance imaging (fMRI).

METHODS

An abstract reasoning task-based fMRI study was carried out on alcohol-dependent subjects (n = 18) and healthy controls (n = 18) to examine neural activation pattern. The study was carried out using a 3-T whole-body magnetic resonance scanner. Preprocessing and post processing was performed using SPM 8 software.

RESULTS

Behavioral data indicated that alcohol-dependent subjects took more time than controls for performing the task but there was no significant difference in their response accuracy. Analysis of the fMRI data indicated that for solving abstract reasoning-based problems, alcohol-dependent subjects showed enhanced right frontoparietal neural activation involving inferior frontal gyrus, post central gyrus, superior parietal lobule, and occipito-temporal gyrus.

CONCLUSIONS

The extensive activation observed in alcohol dependents as compared to controls suggests that alcohol dependents recruit additional brain areas to meet the behavioral demands for equivalent task performance. The results are consistent with previous fMRI studies suggesting decreased neural efficiency of relevant brain networks or compensatory mechanisms for the execution of task for showing an equivalent performance.

Function and dysfunction of prefrontal brain circuitry in alcoholic Korsakoff's syndrome

The signature symptom of alcohol-induced persisting amnestic disorder, more commonly referred to as alcoholic Korsakoff's syndrome (KS), is anterograde amnesia, or memory loss for recent events, and until the mid 20th Century, the putative brain damage was considered to be in diencephalic and medial temporal lobe structures. Overall intelligence, as measured by standardized IQ tests, usually remains intact. Preservation of IQ occurs because memories formed before the onset of prolonged heavy drinking--the types of information and abilities tapped by intelligence tests--remain relatively well preserved compared with memories recently acquired. However, clinical and experimental evidence has shown that neurobehavioral dysfunction in alcoholic patients with KS does include nonmnemonic abilities, and further brain damage involves extensive frontal and limbic circuitries. Among the abnormalities are confabulation, disruption of elements of executive functioning and cognitive control, and emotional impairments. Here, we discuss the relationship between neurobehavioral impairments in KS and alcoholism-related brain damage. More specifically, we examine the role of damage to prefrontal brain systems in the neuropsychological profile of alcoholic KS.

Hippocampus, space, and memory

We examine two different descriptions of the behavioral functions of the hippocampal system. One emphasizes spatially organized behaviors, especially those using cognitive maps. The other emphasizes memory, particularly working memory, a short-term memory that requires iexible stimulus-response associations and is highly susceptible to interference. The predictive value of the spatial and memory descriptions were evaluated by testing rats with damage to the hippocampal system in a series of experiments, independently manipulating the spatial and memory characteristics of a behavioral task. No dissociations were found when the spatial characteristics of the stimuli to be remembered were changed; lesions produced a similar deficit in both spatial and nonspatial test procedures, indicating that the hippocampus was similarly involved regardless of the spatial nature of the task. In contrast, a marked dissociation was found when the memory requirements were altered. Rats with lesions were able to perform accurately in tasks that could be solved exclusively on the basis of reference memory. They performed at chance levels and showed no signs of recovery even with extensive postoperative training in tasks that required working memory. In one experiment all the characteristics of the reference memory and working memory procedures were identical except the type of memory required. Consequently, the behavioral dissociation cannot be explained by differences in attention, motivation, response inhibition, or the type of stimuli to be remembered. As a result of these experiments we propose that the hippocampus is selectively involved in behaviors that require working memory, irrespective of the type of material (spatial or nonspatial) that is to be processed by that memory.

The impact of chronic cigarette smoking on recovery from cortical gray matter perfusion deficits in alcohol dependence: longitudinal arterial spin labeling MRI

BACKGROUND

Neuroimaging studies reported cerebral perfusion abnormalities in individuals with alcohol use disorders. However, no longitudinal magnetic resonance imaging (MRI) studies of cerebral perfusion changes during abstinence from alcohol have been reported.

METHODS

Arterial spin labeling MRI was used to evaluate cortical gray matter perfusion changes in short-term abstinent alcohol dependent individuals in treatment and to assess the impact of chronic cigarette smoking on perfusion changes during abstinence. Seventy-six patients were scanned at least once. Data from 19 non-smoking (17 males, 2 females) and 22 smoking (21 males, 1 female) patients scanned at 1 and 5 weeks of abstinence were used to assess perfusion changes over time. Twenty-eight age-equated healthy controls (25 males, 3 females) were scanned for cross-sectional comparison, 13 of them were scanned twice. Given the age range of the cohort (28 to 68 years), age was used as a covariate in the analyses. Mean perfusion was measured in voxels of at least 80% gray matter in the frontal and parietal lobes and related to neurocognitive and substance use measures.

RESULTS

At 1 week of abstinence, frontal and parietal gray matter perfusion in smoking alcoholics was not significantly different from that in non-smoking alcoholics, but each group's perfusion values were significantly lower than in controls. After 5 weeks of abstinence, perfusion of frontal and parietal gray matter in non-smoking alcoholics was significantly higher than that at baseline. However, in smoking alcoholics, perfusion was not significantly different between the time-points in either region. The total number of cigarettes smoked per day was negatively correlated with frontal gray matter perfusion measured at 5 weeks of abstinence. Lobar perfusion measures did not correlate significantly with drinking severity or cognitive domain measures at either time-point.

CONCLUSION

Although cerebral perfusion in alcohol dependent individuals shows improvement with abstinence from alcohol, cigarette smoking appears to hinder perfusion improvement.

Is CT scan a valid indicator of brain atrophy in alcoholism?

The effect of ingesting varying quantities of alcohol upon the structure and function of the brain was studied using CT scan and psychometric testing. Nutritional status was also assessed. Alcoholics, heavy, moderate and light social drinkers were examined and their results compared with a normal control series. It was concluded that a daily consumption of more than 40 grams alcohol per day, "the safe level" results in brain damage. The latter may partially reverse with abstinence and having reversed maintain improvement, even though patients then resume drinking at the "safe level". The role of thiamin in brain function is still unclear.

The neuropathology of alcohol-related brain damage

Excessive alcohol use can cause structural and functional abnormalities of the brain and this has significant health, social and economic implications for most countries in the world. Even heavy social drinkers who have no specific neurological or hepatic problems show signs of regional brain damage and cognitive dysfunction. Changes are more severe and other brain regions are damaged in patients who have additional vitamin B1 (thiamine) deficiency (Wernicke-Korsakoff syndrome). Quantitative studies and improvements in neuroimaging have contributed significantly to the documentation of these changes but mechanisms underlying the damage are not understood. A human brain bank targeting alcohol cases has been established in Sydney, Australia, and tissues can be used for structural and molecular studies and to test hypotheses developed from animal models and in vivo studies. The recognition of potentially reversible changes and preventative medical approaches are important public health issues.

Imaging dementing illnesses

Dementia is an impairment of mental ability representing a decline from that level previously reached by the individual. It is usually of insidious onset, associated with neurologic changes, and results in the inability to appropriately interact with one's environment. Dementias may be static, progressive, or reversible, and have many etiologies. One percent of the population above age 40 suffers from dementia and this figure rises to 7% above age 80 and 50% above age 90. Forty-five percent of dementias are due to Alzheimer disease (AD) followed closely by vascular dementia. A stage along the way to dementia is mild cognitive impairment (MCI). There are various definitions but the simplest ones refer to a person who has some memory problems but can continue to live independently. A more specific description refers to deficits in two or more areas of cognition >1.5 SD below mean for the individuals age and education. Although previously considered a part of normal aging, a recent study has shown MCI to be a precursor of Alzheimer disease (1). In a cohort of nuns and priests studied annually until they developed MCI or dementia and died. 180 brains in this study have already been autopsied (37 MCI, 60 with no impairment, 53 with dementia). Pathologists measured theamount of AD pathology and cerebral infarcts. Of 37 with MCI, more than half had AD by pathology, 1/3 had infarcts (5 with both) and 14 did not have either pathology. One third of the 180 with average age of 85 had no cognitive decline! Since this study showed MCI patients to have Alzheimer disease pathology in their brains, recognition of MCI clinically is important for institution of therapy, although there has not yet been an effective therapy developed.

Myelinated nerve fibres in the subcortical white matter of cerebral hemispheres are preserved in alcoholic subjects

Previous studies have found that the primary change in the brain of chronic alcoholics is a selective loss of white matter in cerebral hemispheres. It is unknown whether the loss of white matter is due to alcohol-induced degeneration of axons in white matter, and this hypothesis has never been tested. We used a newly developed stereological method to investigate whether the length and diameter of myelinated fibres change in the subcortical white matter of male alcoholic subjects. We found no significant differences between control and alcoholic subjects with respect to the total volume, total length, and mean diameter of myelinated fibres in white matter. Our results do not find any support for the hypothesis that chronic alcoholic subjects may suffer from a degeneration of axons (myelinated fibres) in white matter in cerebral hemispheres.

Does liver-disease aetiology have a role in cerebral blood-flow alterations in liver cirrhosis?

BACKGROUND

Studies using brain-imaging techniques have shown changes in regional blood flow (rCBF) in patients with liver cirrhosis. It remains unknown whether the aetiology of liver disease accounts for these changes.

AIMS

To evaluate whether the aetiology of liver cirrhosis is associated with different patterns of rCBF.

MATERIALS AND METHODS

A total of 50 patients with end-stage liver disease and no overt encephalopathy were studied. Thirteen age-matched subjects admitted to the neurology department for headache were used as controls. Exclusion criteria were focal brain lesions, severe brain atrophy and any abnormalities found on computed tomography scan suggesting other central nervous system diseases, alcohol intake or use of neuroactive drugs for at least 6 months. rCBF was assessed using single-positron-emission tomography (SPECT) with 99mTc-hexamethylpropylene amine oxime (99mTc-HM-PAO) as a tracer in all patients and controls. The Mann-Whitney U test was used for statistical analysis.

RESULTS

The liver-disease aetiology was as follows: alcoholic (A) in 19 patients; viral (V) (hepatitis B virus, hepatitis D virus, hepatitis C virus) in 14 patients; alcoholic with concomitant viral (A + V) in five patients; and cholestatic (C) (primary biliary cirrhosis, primary sclerosing cholangitis) in 12 patients. SPECT showed significantly lower rCBF in cirrhotic patients than in controls for most cortical and subcortical regions and in alcoholic and viral patients than in cholestatic liver disease patients for some cortical regions. When patients were grouped according to previous alcohol abuse (including cases with a concomitant viral aetiology), rCBF was significantly lower in the frontal superior, medial and temporal inferior regions in the alcoholic group.

CONCLUSIONS

Cerebral blood flow is significantly lower in patients with liver cirrhosis than in controls and, among cirrhotics, it is lower in alcoholic and viral cirrhosis than in cholestatic liver disease. In patients with previous alcohol abuse, cerebral blood flow was significantly more reduced in the frontal and temporal regions compared with patients without previous alcohol abuse.

Linear CT-scan measurements in alcohol-dependent patients with and without delirium tremens

The aims of the present study were to examine whether chronic alcohol dependence and the development of delirium tremens are characterized by changes in linear CT measurements of brain liquor spaces and intracranial distances indicative of prefrontal atrophy, and frontal (sub)cortical or temporal (sub)cortical atrophy. Toward this end linear measurements were performed in 47 alcohol dependent patients with and without a history of delirium tremens and in 10 healthy volunteers using CT-scanning. The following linear measurements were calculated: (1) the Evans ratio; (2) the cella media index (CMI); (3) the maximum width of the third ventricle; (4) the maximum width of the fourth ventricle; (5) the maximum frontal subarachnoid space (MFSS); (6) the maximum width of the anterior interhemispheric fissure (MIF), and (7) the maximum width of the Sylvian fissure (MSF). The alcoholics were divided into subgroups according to the Münchner Alkoholismus Test (MALT) and the presence of delirium tremens. The MFSS of the alcohol-dependent patients was significantly larger than that of the controls. The MIF and MSF of high MALT scorers were significantly larger than those of low scorers and controls. Alcohol-dependent patients with a known history of delirium tremens had significantly larger MIF and MSF than did patients without delirium tremens and controls. The results suggest that alcohol dependence is characterized by prefrontal atrophy, and that frontal cortical and temporal (sub)cortical atrophy may be related to the development of delirium tremens.

Atrophy of the corpus callosum in chronic alcoholism

To determine the prevalence of corpus callosum atrophy in chronic alcoholics and its relationship to cognitive function and brain atrophy, a prospective clinicoradiologic study was carried out in 28 right-handed male patients with chronic alcoholism and 14 age- and sex-matched right-handed control subjects. Clinical evaluation, neuropsychological testing and measurement of the midsagittal corpus callosum area and thickness (genu, truncus and splenium), as well as the frontal lobe index and the width of the cortical sulci on T1- and T2-weighted magnetic resonance images were performed. Compared to controls, alcoholics had significantly decreased corpus callosum area and thickness, mainly in the genu. Two-thirds had a corpus callosum area 2 SD below the mean of the control group. The sagittal area of the corpus callosum body correlated negatively with the degree of frontal and cortical atrophies (r = -0.5579 and -0.6853, respectively p < 0.01, both). Alcoholics with corpus callosum atrophy exhibited impairment of visual and logical memories (p < 0.05 both) and those with reduced thickness of the genu showed impairment of frontal lobe tasks (p < 0.05). The reduction of corpus callosum indices (age-corrected) also correlated with the total lifetime dose of ethanol consumed (r = 0.6107, p < 0.001), but was not related to nutritional status or electrolyte imbalance. Atrophy of the corpus callosum is common among alcoholic patients and may reflect the severity and pattern of cortical damage. The degree of this atrophy also correlated with the severity of ethanol intake.

Long-term effect of postnatal alcohol exposure on the number of cells in the neocortex of the rat: a stereological study

Behavioral and morphological studies suggest that exposure to alcohol during development may cause damage in the neocortex. In this study, rat pups were exposed to alcohol during the brain growth spurt and examined at adulthood to ascertain the long-term effect of alcohol exposure on the neocortex. Four-day-old rat pups were surgically implanted with an intragastric cannula while under ether anesthesia and artificially reared from postnatal day (PN) 4 through PN11. Two of the consecutive 12 daily feeds contained either alcohol (4.5 g/kg; alcohol-exposed) or an isocaloric maltose/dextrin solution (gastrostomy control) from PN4 through PN9. On PN115, animals were perfused intracardially and the brains removed. Unbiased stereological methods were used to determine the neocortical volume, the total number of neurons and glial cells in the entire neocortex and in layer V, and the mean cell volume of neurons or mean nuclear volume of glial cells in layer V. No effect of alcohol was seen in the neuronal population on either cell number or mean cell volume, nor was there any difference in the total number or mean nuclear volume of glial cells in layer V. These findings suggest that neither the entire neocortex nor layer V alone are vulnerable to permanent alcohol-induced cell death.

Medical manifestations of alcoholism in the elderly

Alcoholism may lead to a great many physical and mental problems in individuals of any age. Elderly alcoholics often have additional problems resulting from the interaction of age related changes in physiology and "heavy" alcohol intake. Some of the more important problems are: Impairment of the immune system with decreased ability to deal with infection or cancer. Increased incidence of hypertension, cardiac arrhythmia, myocardial infarction, and cardiomyopathy. Increased incidence of stroke. Alcohol dementia. Increased incidence of esophageal and other cancers. Cirrhosis and other liver disease. Malnutrition. There seems to be no area in which even moderate alcohol intake is of definite benefit, and some areas in which even small amounts are detrimental.

Brain atrophy and cognitive function in older abstinent alcoholic men

We used computer-aided magnetic resonance image analysis and an age-normed battery of neuropsychological tests to measure brain atrophy and cognitive function in 14 older abstinent alcoholic men and 11 older controls in the expectation that these subject groups would show the greatest and most persistent cerebral effects consequent to chronic alcoholism. The abstinent alcoholics exhibited cognitive impairments (primarily in memory and visual-spatial-motor skills) compared with the controls. In contrast, we found no difference in global cerebral atrophy between the groups, although two alcoholics had extensive atrophy compared with all other subjects. However, there was a stronger association between age and ventricular dilation in the alcoholic sample compared with controls. We conclude that a substrate other than magnetic resonance imaging-detectable global atrophy must underlie the persistent cognitive impairments evident in the sampled alcoholics. Furthermore, if there are global atrophic changes in the brain associated with chronic alcoholism, these effects are not ubiquitous and/or may be reversible in most patients with sufficient abstinence.