Alcoholism: cognitive disorders and differential diagnoses
Alcohol addiction illness is described as an unidimensional continuum in the DSM-V called “alcohol use disorder”. Numerous studies have found cerebral and cognitive modifications in people with an abnormal alcohol consumption according to the OMS’s recommendations.
Neuropsychological disorders in alcohol dependence
Cognitive functions affected by alcohol, despite a massive heterogeneity, are: executive functions, episodic memory, visuospatial and psychomotor abilities and emotional and social cognition disorders. Biological factors can be attributed to them (genetic, age, sex, sociocultural rank and cognitive reserve) but also consumption pattern and alcohol addiction consequences (nutritional deficiency). The study highlights three deficits profiles.
Attentional and executive function
A dysexecutive syndrome pattern with executive and attentional deficits like ideomotor slowing in tasks with high attentional control, a slow information treatment, flexibility, inhibition, planification, conceptualization and working memory manipulation deficits, difficulties in taking decisions and impulsivity which leads to an incapacity to cease alcohol consumption.
Visuo-spatial information processing and episodic memory
A dysexecutive and memory pattern with severe visuospatial and episodic memory deficits, with a slower and difficult verbal and non-verbal learning because of a lack of strategies when encoding information. Also, difficulties to recall and identify the source of a memory because the experience of memories state of consciousness is unsure (autonoetic consciousness).
Metamemory
A general cognitive and intellectual deficit pattern with metamemory alteration leading people to an incapacity to use strategically their cognitive functions to compensate for their memory issues. They also underestimate the size of their difficulties with a minor form of anosognosia.
Emotional disorders
Alcohol-dependent patients have difficulties identifying and describing their own emotions and those of others. They have a reduced imaginary life and focus their thoughts on concrete rather than emotional aspects. This emotional component of alexithymia is associated with difficulty in developing empathy for others and troubles in the recognition of facial emotions, thus altering their theory of mind (TOM). These deficits can lead to social isolation inducing realcoholization.
Psychomotor disorders
Psychomotor disorders are also described with reduced speed of execution, particularly in attentional tasks due to an impaired motor component. In addition, ataxic disorders including postural instability and gait disorders are reported and increased when their eyes are closed and impairment of coordination and fine dexterity of the upper limbs.
Differential diagnosis
The heterogeneity of the nature and severity of alcohol dependence deficits leads to a difficult differential diagnosis, particularly with Korsakoff’s syndrome or alcoholic dementia.
Alcohol dependence Korsakoff’s syndrome and alcoholic dementia
Korsakoff’s syndrome (SK) is linked to a deficiency of thiamin or vitamin B1, causing irreversible damages to the brain like anterograde amnesia (forgetting information as it comes in), episodic memory, executive functioning and visuo-spatial impairment and false recognition, confabulations and anosognosia. Those syndrome most often follows Gayet’s Wernicke’s Encephalopathy which could partly explain the cognitive heterogeneity in alcohol-dependent patients (ADP). The severity of the disorder and the disproportionate impairment of episodic memory encoding abilities, distinguished SK patients from ADP. This supports the hypothesis of a continuum of neuropsychological impairment ranging from mild to moderate disorders for ADP to severe and permanent disorders for SK patients which might be extended to alcoholic dementia according to studies.
However, these diagnostic criterias are similar to those of Alzheimer’s disease (AD) but have not been empirically validated yet. Therefore, scientists have tried to propose new criterias specific to Alcoholic Disorder while relying on models of AD, regarding their relatively similar clinical semiology. The reversibility of the disorders with abstinence in alcoholic dementia highlight the difference with AD. However, the diagnosis of alcoholic disorder remains complicated in the absence of specific neuropathological arguments.
Alcohol, addiction and dementia
The impact of alcohol consumption on cognitive functioning depends on drinking patterns, especially for older people. However, some studies show different results:
- The prevalence of dementia is lower among older people who consume three to four standard glasses of alcohol per day than among abstainers.
- The risk of developing dementia in the event of excessive consumption is 4.6 times greater. Indeed, in these studies, 9 to 23% of elderly patients with a history of alcohol abuse have dementia, whereas the prevalence in the general population is only 5%.
Is the development of a neurodegenerative disease in an ADP related to the neurological effects of chronic alcohol consumption or to a neurodegenerative process?
Studies show that chronic alcohol consumption and AD would lead to a pattern of similar brain atrophy. However, excessive alcohol consumption would not accelerate the progression of AD and there is no link between excessive alcohol consumption and the density of senile plaques (i.e., a neurological feature characteristic of AD).
Fronto-temporal degeneration (FTD) is characterised by the initial appearance of behavioural disorders like an appetite for sweet foods and drinks, including alcohol. Alcohol disorders are indeed observed in 30 to 41% of patients with FTD. Despite that, symptoms of alcohol dependence are rarely observed in FTD patients. This highlights the importance of clinical interviewing with the patient and family to learn about the patient’s history of alcohol use, and to determine whether or not alcohol use is secondary to dementia symptoms.The proximity of the neuropsychological picture of FTD and alcohol dependence makes the differential diagnosis sometimes complicated.
Alcohol, addiction and normal aging
Certain cognitive changes observed in alcohol dependence are close to those observed in normal aging. Some studies have sought to characterise the neuropsychological profile of alcohol-dependent patients and healthy subjects, both young and elderly: the results are not in favour of an interaction between alcohol dependence and aging. Indeed, the results show that alcohol-dependent patients (young or old) present a pattern of cognitive performance that is qualitatively different from healthy subjects. This suggests that the processes underlying the effects of alcohol dependence and aging are different.
Alcohol and cranial trauma (CT)
Comorbidity between alcohol dependency and CT is common. Some studies have shown that between a quarter and a third of CT are due to the acute effects of alcohol. However, the links between alcohol and CT are complex and the way in which these two factors interact are not clear. On the neuropsychological level, alcohol dependency and CT have a close symptomatology. It has been suggested that chronic alcohol consumption could potentiate the neuropsychological after-effects of CT. Studies have shown that the recovery of neuropsychological and emotional after-effects and the outcome of CT were less favourable in patients with a history of alcohol abuse, combined to a greater risk of an alcoholic relapse that could exacerbate the after-effects already present. These data support the importance of managing the alcohol abuse history of brain injured persons in rehabilitation and reintegration, but also the importance of screening for misuse behaviour in brain injured persons.
Conclusion
Many neuropsychological deficits can be observed in certain alcohol-dependent patients without neurological impairment. The difficulty for clinicians results in a possible differential diagnosis with other pathologies. Today, there is no certainty as to the role of alcohol dependence disorders in the appearance, development or enhancement of the cognitive changes observed in normal aging, certain dementias or head trauma.
Authors : Pauline Guilbaud, Lucie Jerez & Ophelie Toublanc
Words we have learned :
- Alcohol consumption (consommation d’alcool),
- Drinking pattern (habitude de consommation d’alcool),
- Underestimate (sous-estimé),
- Gait (allure, démarche),
- Upper limbs (membres supérieurs),
- Acute effects (effets aigus),
- Relapse (rechute),
- Misuse behaviour (comportement d’abus/ de mésusage)