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[Cognitive deterioration in Huntington disease].

OBJECTIVES
To review, summarize and update data on the pattern of cognitive deterioration in Huntington's disease (HD).


DEVELOPMENT
HD represents a paradigm of frontostriatal dementia in which cognitive deterioration affects three large domains: memory, executive and visual-spatial functions. Episodic explicit memory deficit mainly affects the processes of information recovery, whilst changes in implicit memory are impaired in learning procedures but not in priming. Executive dysfunction constitutes an essential characteristic, affecting the working memory, attention, sequencing and planning. Complex visual-spatial functions are severely affected and this may affect recognition of complex figures and facial gestures. Some of these mental changes may be detected during preclinical stages. At the present time, since it is possible to make a definite genetic diagnosis and there is neuropathological data on HD, this condition is considered to be an excellent clinical model for the study of the cognitive functions carried out by the cortico-striatal circuits.


CONCLUSIONS
Using a multidisciplinary approach a cognitive model has been established in which the corpus striatum is considered to be the basic structure for selection of information which will generate the appropriate response, both motor and behavioral, for the context involved. Loss of this capacity leads to mental rigidity and perseveration in conduct, which are typical of the cognitive disorders of HD.