The Significance of Family History Status in Relation to Neuropsychological Test Performance and Cerebral Glucose Metabolism Studied with Positron Emission Tomography in Older Alcoholic Patients

Fluorodeoxyglucose positron emission tomography scans in patients with alcohol use disorder

BACKGROUND

Diminished uptake of fluorodeoxyglucose (FDG) has been observed in patients with alcohol use disorder (AUD) but little statistical contrast of the regional brain deficits has been undertaken. This study examined prefrontal cortex inter-regional Brodmann area differences to delineate patterns associated with behavioral, neurotransmitter, and general toxicity hypotheses of cerebral involvement in AUD.

METHODS

We obtained data from FDG positron emission tomography (PET) and anatomical magnetic resonance imaging (MRI) for 87 patients with AUD and 41 age- and sex-matched healthy volunteers. Patients were alcohol dependent and had negative breathalyzer tests at the time of imaging. They were assessed with the Beck Depression Inventory, Alcohol Urge Questionnaire, Obsessive Compulsive Drinking Scale, Spielberger State/Trait Anxiety Scale, Buss-Durkee Hostility Inventory, and the Drinker Inventory of Consequences (DrInC). PET images were co-registered to MRI and both voxel × voxel statistical mapping and stereotaxic regions of interest were obtained.

RESULTS

Compared with healthy volunteers, patients with AUD had lower relative metabolic rates in the frontal, temporal, and parietal lobes, localizable most prominently to the dorsolateral and nearly all orbital prefrontal cortex, superior temporal gyrus, and inferior parietal lobule. In contrast, metabolic rates in the medial orbitofrontal and anterior cingulate cortex, and the subcortical structures (thalamus, cerebellum, ventral striatum, and the dorsal raphe nucleus) in patients were significantly greater. The severity of alcohol-related consequences as assessed by the DrInC scale was most highly associated with lower metabolism in the caudate, dorsolateral prefrontal, frontopolar, and anteroposterior cingulate cortex.

CONCLUSIONS

Despite widespread metabolic abnormalities, decreases in AUD were most marked in frontal executive areas, consistent with diminished impulse control, and increases were most prominent in the striatum and cingulate areas, consistent with a suppressed reward system.

Sex differences in alcohol-related neurobehavioral consequences

In this chapter, we review existing research regarding sex differences in alcohol's effects on neurobehavioral functions/processes. Drawn largely from laboratory studies, literature regarding acute alcohol administration and chronic alcohol misuse is explored focusing on commonly employed neuropsychologic domains (e.g., executive function, visuospatial skills, learning and memory, gait and balance), neurophysiologic measures (e.g., electroencephalography and event-related potentials), and structural and functional neuroimaging (e.g., magnetic resonance imaging (MRI), functional MRI, diffusion tensor imaging, positron emission tomography, and magnetic resonance spectroscopy). To provide a historical perspective on the development of these questions, we have included reference to early and more recent research. Additionally, specific biases, knowledge gaps, and continuing controversies are noted.

Neuroimaging for drug addiction and related behaviors

In this review, we highlight the role of neuroimaging techniques in studying the emotional and cognitive-behavioral components of the addiction syndrome by focusing on the neural substrates subserving them. The phenomenology of drug addiction can be characterized by a recurrent pattern of subjective experiences that includes drug intoxication, craving, bingeing, and withdrawal with the cycle culminating in a persistent preoccupation with obtaining, consuming, and recovering from the drug. In the past two decades, imaging studies of drug addiction have demonstrated deficits in brain circuits related to reward and impulsivity. The current review focuses on studies employing positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and electroencephalography (EEG) to investigate these behaviors in drug-addicted human populations. We begin with a brief account of drug addiction followed by a technical account of each of these imaging modalities. We then discuss how these techniques have uniquely contributed to a deeper understanding of addictive behaviors.

Executive dysfunction as a risk marker for substance abuse: the role of impulsive personality traits

The relationships between family history of substance use, executive functions, impaired decision making, and current substance dependence are the focus of this study. Thirty-eight substance-dependent inpatients were compared with 30 community controls on performance on the Wisconsin Card Sorting Test, Trail-Making Test-B, the Stroop Color Word Test, the Wais-II Digit Span, and the Iowa Gambling Task. Recent alcohol use, depressive symptoms, and impulsivity were also assessed. As hypothesized, individuals with substance dependence exhibited poorer executive functioning. Family history status was modestly related to impaired performance on tests designed to measure the integrity of the dorsolateral prefrontal cortex. In particular, substance-dependent, family history positive individuals performed less well on the Wisconsin Card Sorting Test than substance-dependent individuals without a family history. Digit Span performances were worse among family history positive controls when compared with family history negative controls. Impulsive personality traits--specifically, difficulty thinking before acting (Urgency)--were related, as hypothesized, to executive functioning. Results indicate that family history status confers an increased risk of impairment beyond that conferred by recent substance abuse, and that impulsive personality traits are related to performance on tests of executive functions. Implications for criminality are discussed.

Conditional Responding is Impaired in Chronic Alcoholics

Bechara (2003) describes a model for disturbances in executive functions related to addiction. This model involves deficits in decision-making and in suppressing pre-potent representations or response patterns. We tested this model in 29 individuals with long-term heavy alcohol dependency and compared their performance with that of 20 control subjects. Only individuals without memory impairment, with normal intelligence and normal visual response times were included. We examined word fluency, object alternation, spatial stimulus-response incompatibility, extra-dimensional shift learning and decision-making using the Gambling task. We subtracted the performance in a control condition from that of the executive condition, in order to focus specifically on the executive component of each task. Only the object alternation and incompatibility tasks revealed significant differences between the group of alcoholics and the control group. Moreover, response times in the object alternation task correlated with duration of alcohol dependency. The results do not argue in favor of a specific deficit in decision-making or in shifting between relevant representations. We conclude that long-term alcohol abuse leads to an impairment in conditional responding, provided the response depends on former reactions or the inhibition of pre-potent response patterns.

Comparisons of Korsakoff and non-Korsakoff alcoholics on neuropsychological tests of prefrontal brain functioning

BACKGROUND

Evidence suggests that alcoholics exhibit particular deficits in brain systems involving the prefrontal cortex, but few studies have directly compared patients with and without Korsakoff's syndrome on measures of prefrontal integrity.

METHODS

Neuropsychological tasks sensitive to dysfunction of frontal brain systems were administered, along with standard tests of memory, intelligence, and visuospatial abilities, to 50 healthy, abstinent, nonamnesic alcoholics, 6 patients with alcohol-induced persisting amnestic disorder (Korsakoff's syndrome), 6 brain-damaged controls with right hemisphere lesions, and 82 healthy nonalcoholic controls.

RESULTS

Korsakoff patients were impaired on tests of memory, fluency, cognitive flexibility, and perseveration. Non-Korsakoff alcoholics showed some frontal system deficits as well, but these were mild. Cognitive deficits in non-Korsakoff alcoholics were related to age, duration of abstinence (less than 5 years), duration of abuse (more than 20 years), and amount of alcohol intake.

CONCLUSIONS

Abnormalities of frontal system functioning are most apparent in alcoholics with Korsakoff's syndrome. In non-Korsakoff alcoholics, factors contributing to cognitive performance are age, duration of abstinence, duration of alcoholism, and amount of alcohol consumed.

Neurocognitive impairment associated with alcohol use disorders: implications for treatment

Between 50% and 80% of individuals with alcohol use disorders experience mild to severe neurocognitive impairment. There is a strong clinical rationale that neurocognitive impairment is an important source of individual difference affecting many aspects of addiction treatment, but empirical tests of the direct influence of impairment on treatment outcome have yielded weak and inconsistent results. The authors address the schism between applied-theoretical perspectives and research evidence by suggesting alternative conceptual models of the relationship between neurocognitive impairment and addiction treatment outcome. Methods to promote neurocognitive recovery and ways in which addiction treatments may be modified to improve psychosocial adaptation are suggested. Specific suggestions for future research that may help clarify the complex relations between neurocognitive impairment and addiction treatment are outlined.

Possible consequences of social drinking in the early stages of Alzheimer disease

Although research supports the idea that alcohol is not a risk factor for developing Alzheimer disease (AD), surprisingly little attention has been given to the role of social drinking in the early stages of the disorder. The current review highlights potential alcohol- and disease-related interactions on neurologic, cognitive, and behavioral functioning in individuals experiencing the early stages of AD. Understanding how alcohol interacts with AD can benefit both treatment providers (eg, interpreting clinical tests) and caregivers (eg, managing disruptive behaviors) by providing important clues to potentially reversible impairments that may negatively affect the everyday functioning of individuals with the disorder.

Brain shrinkage in alcoholics: a decade on and what have we learned?

Brain atrophy in alcoholics has been identified using both radiological and pathological techniques. However the magnitude and topography of the atrophy, and the factors which contribute to it, are unclear. This review compares the results of imaging and pathological studies in alcoholics examining variables which may contribute to any discrepancies. We conclude that significant brain damage does occur as a result of alcohol abuse per se, that the damage is regionally specific with the frontal lobes being particularly affected, and that both grey matter and white matter components are damaged.

DNA fragmentation during exposure of rat cerebella to ethanol under hypoxia imposed in vitro

To gain a better understanding into the mechanisms of damage incurred by neurons in periods following heavy alcohol exposure during development, we used an in vitro system to monitor the effects of alcohol and hypoxia on cell survival and DNA integrity. Samples representing the first few hours of exposure to alcohol and hypoxia were compared to those resulting from hypoxia alone. Measurements were taken from cell counts using Trypan blue exclusion and TUNEL assays as well as digital scans of the ethidium bromide fluorescence of genomic DNA isolated from the treated tissue. We found that DNA degradation from hypoxia was accelerated by several hours in the presence of 100 mM ethanol. This result depended on age, with adult animals (>8 months) having a similar response to 4-day postnatal animals, while the effect on 10-day postnatal animals and those of intermediate age (45 days postnatal) was increasingly delayed. Different methods of inducing the processive degradation of DNA produced laddering typical of apoptosis, a biphasic degradative process, or patterns usually associated with necrosis.