Reversibility of brain-stem evoked potential abnormalities in abstinent chronic alcoholics: one year follow-up

Cognitive Event-Related Potentials and Alcoholism

The discipline of neuropsychiatry tries to bridge the gap between neurology and psychiatry in order to gain insight into the biological bases of psychiatric disorders. A principal tool is electrophysiological assessments, as, for instance, event-related potentials (ERPs). In this paper, we will review the current main findings concerning the status of cognitive ERPs in a specific psychiatric disease, i.e., chronic alcoholism. First, delayed P300 latency and reduced P300 amplitude are a common and robust finding in chronic alcoholics. Our aim will be to insert this empirical finding into the growing knowledge of molecular actions of alcohol and genetic patterns of alcohol dependence together with a more precise identification of alcohol-influenced neuronal and psychopathological processes. We will show how this may help us to reach a better understanding of this pathology. Second, an important set of data also pointed out that earlier ERP components, such as the N100, the mismatch negativity (MMN), the P100, and the N170, were also affected by chronic consumption of alcohol. Therefore, as the entire information-processing system seemed to be altered, these results deserved to be discussed, at least concerning their main clinical implications. Finally, although long term consequences of alcohol abuse have been extensively described, little is known about the detrimental effect on neural and cognitive processes of massive alcohol intake over a short period of time (e.g., binge drinking). Recent data on this new and challenging issue will be outlined.

Social cognition in alcoholism: a link to prefrontal cortex dysfunction?

AIMS

Alcoholism is associated with a range of cognitive deficits. These deficits might be explained by the 'frontal lobe hypothesis' which suggests a specific vulnerability of the prefrontal cortex (PFC) to the neurotoxic effects of alcohol. Social cognition is thought to be processed in the PFC, but so far only few studies have addressed the issue of social cognition deficits in alcoholism. This review aims to evaluate the deficits in social cognition in alcoholic patients. In addition an outline for future perspectives is given.

METHODS

Medline and Psyclit searches were performed for a 30-year period (1977-2007).

RESULTS

Alcoholism is associated clearly with social cognition impairments which include emotional face and prosody perception problems, theory of mind deficits and humour processing difficulties.

CONCLUSIONS

In summary, the social cognition impairments are consistent with the frontal lobe hypothesis of alcoholism. Future studies should focus on (i) the delineation of the basic cognitive processes which underlie social cognition deficits; and (ii) their relevance as predictors of treatment outcome in alcoholism.

Visual evoked potentials in chronic alcoholism

In order to evaluate the effect of alcohol consumption and the effect of abstinence on central nervous system generated parameters, we performed pattern visual evoked potential (PVEP) recordings on chronic alcoholics. The study was conducted on forty patients diagnosed as chronic alcoholics according to DSM IV criteria. They were aged mean: 42, and had histories of alcohol abuse for at least six years (mean: 21). 15% of the patients demonstrated abnormal VEP results at least in one tested eye. In order to test the effect of abstinence period on P100 latency values, alcoholics were divided in to two subgroups. Group I (Gr I) consisted twenty-four alcoholics who had been abstinent for less than thirty days (mean: 14), and Group II (Gr II) consisted sixteen alcoholics who had been abstinent for more than thirty and less than seventy-six days (mean: 38) The mean P100 latency of Gr I and Gr II was 101 and 102 milliseconds (ms) respectively; and when compared to normal controls the difference was statistically significant (p: 0.016, p: 0.009). Abnormal VEP in asymptomatic chronic alcoholics suggests that they may be useful in the detection of early changes and in following the progress of patients with the disorder.

The utility of neurophysiological markers in the study of alcoholism

OBJECTIVE

This review attempts to differentiate neuroelectric measures (electroencephalogram (EEG), event-related potentials (ERPs) and event-related oscillations (EROs)) related to acute and chronic effects of alcohol on the brain from those that reflect underlying deficits related to the predisposition to develop alcoholism and related disorders. The utility of these neuroelectric measures as endophenotypes for psychiatric genetics is evaluated.

METHODS

This article reviews the main findings of EEG and ERP abnormalities in alcoholics, offspring of alcoholics at high risk to develop alcoholism and the electrophysiological effects of alcohol on high risk compared to low-risk offspring. It highlights findings using EROs, a fast developing tool in examining brain function and cognition. It also reviews evidence of genetic findings related to these electrophysiological measures and their relationship to clinical diagnosis.

RESULTS

Many of these abnormal neuroelectric measures are under genetic control, may precede the development of alcoholism, and may be markers of a predisposition toward the development of a spectrum of disinhibitory conditions including alcoholism. Genetic loci underlying some neuroelectic measures that involve neurotransmitter systems of the brain have been identified.

CONCLUSIONS

Quantitative neuroelectric measures (EEG, ERPs, EROs) provide valuable endophenotypes in the study of genetic risk to develop alcoholism and related disorders.

SIGNIFICANCE

Genetic studies of neuroelectric endophenotypes offer a powerful strategy for identifying susceptibility genes for developing psychiatric disorders, and provide novel insights into etiological factors.

Blink Reflex Abnormalities in Chronic Alcoholics

PURPOSE

The aim of the present study was to evaluate the efficacy of blink reflex as a method for obtaining early diagnosis of cranial nerve involvement in alcoholic patients.

MATERIALS AND METHODS

The study was conducted on 30 male alcoholics with a mean age of 43 years. They had histories of alcohol abuse for at least 6 years (mean: 25). At the time of recording, they had undergone detoxification treatment for a mean of 27 days.

RESULTS

R1 (early response), R2Y (second ipsilateral response), and R2C (second contralateral response) latencies in alcoholics were prolonged relative to controls and the differences were statistically significant (p < 0.02, p < 0.001, p < 0.001, respectively). According to the defined criteria, 40% of the patients had abnormal responses, and the most common abnormality was the unilateral prolongation of R1 (13%).

CONCLUSION

Finding abnormal blink reflex responses in alcoholic patients has suggested that blink reflex testing is a useful method for the evaluation of subclinical cranial nerve involvement in alcoholic patients. Blink reflex testing may be useful in detecting early changes and in the follow-up of alcoholic disorder.

The decade 1989-1998 in Spanish psychology: an analysis of research in psychobiology

In this paper, we present an analysis of the research published during the 1989-1998 decade by tenured Spanish faculty members from the area of psychobiology. Database search and direct correspondence with the 110 faculty members rendered a list of 904 psychobiological papers. Classification and analysis of these papers led to the definition of at least 70 different research trends. Topics are grouped into several specific research areas: Learning and Memory; Development and Neural Plasticity; Emotion and Stress; Ethology; Neuropsychology; Sensory Processing; and Psychopharmacology. The international dissemination of this research, published in journals of high impact index, and the increasing number of papers are two noteworthy features.

Acute and chronic effects of alcohol on preattentive auditory processing as reflected by mismatch negativity

Chronic alcoholism, a major worldwide health problem, is associated with a variety of neurocognitive changes in the afflicted individuals. The precise neurophysiological basis of these changes is not yet understood. Mismatch negativity (MMN) is a preattentive event-related potential component indexing cortical auditory memory traces and automatic change detection in the brain that can be used to study the neural basis of cognitive impairments in various neurodegenerative diseases. MMN studies have revealed that even a low dose of acute alcohol significantly impairs automatic change detection and involuntary attention shifting. Recent MMN results on chronic alcoholism in turn suggest that auditory sensory traces decay slightly faster and are substantially more vulnerable to the distracting effect of backward masking in alcoholics than in healthy subjects. Furthermore, chronic alcohol abuse might accelerate the age-related impairment of automatic change detection. There is also evidence that the MMN changes might predict impaired performance in behavioral memory and attention tasks in alcoholics. In MMN studies of detoxified alcoholics, however, many confounding factors have to be taken into account. For instance, postwithdrawal brain hyperexcitability might be associated with a slightly enhanced or accelerated MMN/MMNm (the magnetic equivalent of MMN). In sum, MMN and MMNm provide an objective noninvasive tool for exploring the neurophysiological functional deficits related to both acute alcohol intoxication and chronic alcoholism.

The contribution of electrophysiology to knowledge of the acute and chronic effects of ethanol

This review describes the effects of ethanol on the components of neuronal transmission and the relationship of such effects to the behavioural actions of ethanol. The concentrations of ethanol with acute actions on voltage-sensitive ion channels are first described, then the actions of ethanol on ligand-gated ion channels, including those controlled by cholinergic receptors, 5-hydroxytryptamine receptors, the various excitatory amino acid receptors, and gamma-aminobutyric acid receptors. Acute effects of ethanol are then described on brain areas thought to be involved in arousal and attention, the reinforcing effects of ethanol, the production of euphoria, the actions of ethanol on motor control, and the amnesic effects of ethanol; the acute effects of ethanol demonstrated by EEG studies are also discussed. Chronic effects of alcohol on neuronal transmission are described in the context of the various components of the ethanol withdrawal syndrome, withdrawal hyperexcitability, dysphoria and anhedonia, withdrawal anxiety, craving, and relapse drinking. Electrophysiological studies on the genetic influences on the effects of ethanol are discussed, particularly the acute actions of ethanol and electrophysiological differences reported in individuals predisposed to alcoholism. The conclusion notes the concentration of studies on the classical transmitters, with relative neglect of the effects of ethanol on peptides and on neuronal interactions between brain areas and integrated patterns of neuronal activity.

Effects of chronic ethanol ingestion on mid-latency auditory evoked potentials depend on length of exposure

We hypothesized that chronic ethanol ingestion is associated with modifications in components of mid-latency auditory evoked potentials (MAEPs). To test this, male Long Evans rats were administered 10% ethanol in drinking water as the sole fluid source for 3, 6, or 9 months. MAEPs were obtained and compared to age-matched control groups. MAEPs were obtained from additional rats after 4 weeks of abstinence. Data were obtained for varying frequencies (4, 8, 16, 24, 32 kHz) and intensities (65, 75, 85 dB SPL). Three months of ethanol exposure was associated with increased latencies and amplitudes of Na and Pa. MAEP components recovered and returned to control values after 4 weeks' abstinence following 3 months of EtOH exposure. Few significant differences were observed in the ethanol-treated or abstinent group after 6 months' exposure. However, 9 months of ethanol exposure revealed a significant increase in latencies and decrease in amplitudes of both Na and Pa components. After 4 weeks of abstinence, the Na and Pa component peak latencies appeared earlier than age-matched controls. The Na and Pa peak amplitudes were slightly greater than the ethanol-treated group; however, they did not recover to control values. These findings suggest that chronic ethanol consumption may produce time-dependent structural and/or neurochemical alterations in substrates for cortical information processing, which may be irreversible. In the present paradigm, this irreversibility may occur after 6 or more months of ethanol intake, and may be detected with the use of MAEPs.

Alcohol, auditory functioning and deafness

This paper reviews studies of alcohol and auditory impairment and the treatment of deaf people with alcohol problems and concludes that: (a) alcohol affects auditory functioning, (b) prenatal exposure to alcohol is a risk factor for hearing impairment in FAS children,