Korsakoff Syndrome in Non-alcoholic Psychiatric Patients. Variable Cognitive Presentation and Impaired Frontotemporal Connectivity

Alcohol Use Disorder and Dementia: A Review

PURPOSE

By 2040, 21.6% of Americans will be over age 65, and the population of those older than age 85 is estimated to reach 14.4 million. Although not causative, older age is a risk factor for dementia: every 5 years beyond age 65, the risk doubles; approximately one-third of those older than age 85 are diagnosed with dementia. As current alcohol consumption among older adults is significantly higher compared to previous generations, a pressing question is whether drinking alcohol increases the risk for Alzheimer's disease or other forms of dementia.

SEARCH METHODS

Databases explored included PubMed, Web of Science, and ScienceDirect. To accomplish this narrative review on the effects of alcohol consumption on dementia risk, the literature covered included clinical diagnoses, epidemiology, neuropsychology, postmortem pathology, neuroimaging and other biomarkers, and translational studies. Searches conducted between January 12 and August 1, 2023, included the following terms and combinations: "aging," "alcoholism," "alcohol use disorder (AUD)," "brain," "CNS," "dementia," "Wernicke," "Korsakoff," "Alzheimer," "vascular," "frontotemporal," "Lewy body," "clinical," "diagnosis," "epidemiology," "pathology," "autopsy," "postmortem," "histology," "cognitive," "motor," "neuropsychological," "magnetic resonance," "imaging," "PET," "ligand," "degeneration," "atrophy," "translational," "rodent," "rat," "mouse," "model," "amyloid," "neurofibrillary tangles," "α-synuclein," or "presenilin." When relevant, "species" (i.e., "humans" or "other animals") was selected as an additional filter. Review articles were avoided when possible.

SEARCH RESULTS

The two terms "alcoholism" and "aging" retrieved about 1,350 papers; adding phrases-for example, "postmortem" or "magnetic resonance"-limited the number to fewer than 100 papers. Using the traditional term, "alcoholism" with "dementia" resulted in 876 citations, but using the currently accepted term "alcohol use disorder (AUD)" with "dementia" produced only 87 papers. Similarly, whereas the terms "Alzheimer's" and "alcoholism" yielded 318 results, "Alzheimer's" and "alcohol use disorder (AUD)" returned only 40 citations. As pertinent postmortem pathology papers were published in the 1950s and recent animal models of Alzheimer's disease were created in the early 2000s, articles referenced span the years 1957 to 2024. In total, more than 5,000 articles were considered; about 400 are herein referenced.

DISCUSSION AND CONCLUSIONS

Chronic alcohol misuse accelerates brain aging and contributes to cognitive impairments, including those in the mnemonic domain. The consensus among studies from multiple disciplines, however, is that alcohol misuse can increase the risk for dementia, but not necessarily Alzheimer's disease. Key issues to consider include the reversibility of brain damage following abstinence from chronic alcohol misuse compared to the degenerative and progressive course of Alzheimer's disease, and the characteristic presence of protein inclusions in the brains of people with Alzheimer's disease, which are absent in the brains of those with AUD.

The temporal lobes and memory

Since the first description of the case of H.M. in the mid-1950s, the debate over the contribution of the mesial temporal lobe (MTL) to human memory functioning has not ceased to stimulate new experimental work and the development of new theoretical models. The early demonstration that despite their devastating memory loss patients with hippocampal damage are still able to learn a number of visuo-motor and visuo-perceptual skills at a normal rate and to be normally primed by verbal and visual material suggested that the term "memory" is actually an umbrella concept that includes very different brain plasticity phenomena and that MTL damage actually impairs only one of these. Subsequent research, which capitalized on a detailed anatomical description of MTL structures and on the close analysis of memory-related phenomena, tried to define the unique role of the MTL structures in brain plasticity and in the government of human behavior. A first hypothesis identified this role in the conscious forms of memory as opposed to implicit ones. In the last two decades, the emphasis has moved to the relational role of the hippocampus in binding together different pieces of unimodal information to provide unitary, multimodal representations of personal experiences.

Korsakoff syndrome: An overlook (Review)

This review aimed to analyze the latest neurobiological findings regarding Korsakoff syndrome, since alcoholism is the most prevalent addiction worldwide. In addition, we analyzed the optimal treatment that can be administered in order to minimize the symptoms and improve the outcome of these patients. The disruption of memory circuits within the brain of alcoholic patients results in the amnestic syndrome known as Korsakoff syndrome. It is generally characterized by a chronic neuropsychiatric syndrome caused by vitamin B1 (thiamine) deficiency. Other categories of patients can develop Korsakoff syndrome without consuming alcohol such as AIDS patients, terminally ill cancer patients, or patients with chronic infections and malnutrition. Vitamin B1 is required in the Krebs cycle for production of adenosine triphosphate (ATP). It is also a cofactor in the production of acetylcholine and certain neurotransmitters. Alcohol consumption can decrease the intake, gastrointestinal absorption and cellular utilization of vitamin B1. Treatment of alcohol withdrawal along with high doses of vitamin B1 can improve the general outcome of patients. A small percentage of patients can recover from Wernicke's encephalopathy with no permanent brain damage. The onset of Korsakoff syndrome darkens the prognosis. Alcohol abstinence is an absolute recommendation and prevents the extension of neural damage.

A patient with Korsakoff syndrome of psychiatric and alcoholic etiology presenting as DSM-5 mild neurocognitive disorder

Background: Wernicke's encephalopathy (WE) and Korsakoff syndrome (KS) are underdiagnosed. The DSM-5 has raised the diagnostic threshold by including KS in the major neurocognitive disorders, which requires that the patient needs help in everyday activities. Methods: We report clinical, neuropsychological, and radiological findings from a patient who developed Wernicke-Korsakoff syndrome as a result of alcohol use and weight loss due to major depression. We assess the diagnosis in the context of the scientific literature on KS and according to the DSM-IV and the DSM-5. Results: The patient developed ataxia during a period of weight loss, thus fulfilling current diagnostic criteria of WE. WE was not diagnosed, but the patient partially improved after parenteral thiamine treatment. However, memory problems became evident, and KS was considered. In neuropsychological examination, the Logical Memory test and the Word List test were abnormal, but the Verbal Pair Associates test was normal (Wechsler Memory Scale-III). There were intrusions in the memory testing. The Wisconsin Card Sorting Test was broadly impaired, but the other test of executive functions (difference between Trail Making B and Trail Making A tests) was normal. There was atrophy of the mammillary bodies, the thalamus, the cerebellum, and in the basal ganglia but not in the frontal lobes. Diffusion tensor imaging showed damage in several tracts, including the uncinate fasciculi, the cinguli, the fornix, and the corona radiata. The patient remained independent in everyday activities. The patient can be diagnosed with KS according to the DSM-IV. According to the DSM-5, the patient has major neurocognitive disorders. Conclusions: Extensive memory testing is essential in the assessment of KS. Patients with a history of WE and typical clinical, neuropsychological, and radiological KS findings may be independent in everyday activities. Strict use of the DSM-5 may worsen the problem of Wernicke-Korsakoff syndrome underdiagnosis by excluding clear KS cases that do not have very severe functional impairment.