Tuesday 26 January 2010

The Neuropsychology of Korsakoff's syndrome

Korsakoff's syndrome is a brain disorder caused by the lack of thiamine (vitamin B1) in the brain, often caused by heavy drinking restricting nutritional intake or through physical changes to the stomach lining restricting its ability to absorb thiamine. The syndrome is named after Sergei Korsakoff, the neuropsychiatrist who popularized the theory

Although often referred to as Korsakoff's psychosis or Korsakoff's dementia, in an attempt to describe its similar features to a dementia or to a psychotic episode, it is in fact best described as a syndrome or a ‘collection of symptoms’. This is because following the initial period of confabulatory/’psychotic-like’ features, cognitive functioning and orientation tends to be restored close to premorbid levels.


Physiology

On a physiological heavy levels of prolonged alcohol use (a neuro-toxic) create enduring changes of chemistry with the brain. Deficiency of thiamine along with prolonged neurotoxicity within the brain result in general cerebral and ventrical atrophy, damage to hippocampus, the medial thalamus and possibly to the mammillary bodies of the hypothalamus.


Neuropsychological Symptoms

Cerebral atrophy inherent in Korsakoff's syndrome presents like an accelerated ageing of the brain. Deficits in speed of information processing are most obvious, along with 6 other key features:

1. anterograde amnesia and
2. retrograde amnesia, severe memory loss
3. confabulation, that is, invented memories which are then taken as true due to gaps in memory sometimes associated with blackouts
4. meager content in conversation
5. lack of insight
6. apathy - the patients lose interest in things quickly and generally appear indifferent to change.

Wernicke's encephalopathy refers to the initial symptoms that often preclude Korsakoff’s syndrome (especially when left untreated). Wernicke's encephalopathy includes symptoms of: involuntary or jerky eye movements, paralysis of muscles, poor balance, staggering gait or inability to walk and drowsiness and confusion. Korsakoff’s syndrome is therefore on the more severe end of a spectrum, and sometimes this spectrum is referred to as: Wernicke-Korsakoff syndrome.


Treatment

Thiamine treatment is often successful in initiating the spontaneous phase of recovery. Longer term recovery focuses upon changes in lifestyle to include alcohol abstinence, regular exercise and a balanced diet.


Recovery

Recovery to premorbid levels of functioning has been repeatedly reported following five years of abstinence from alcohol, although may partly be explained by the ageing process ‘catching-up’ to put it crudely.

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