WAIS-R features of preclinical Huntington's disease: implications for early detection.
OBJECTIVE
The main purpose of the study was to determine whether the predicted age of onset of Huntington's disease (HD) affects cognitive function as measured by the Wechsler Adult Intelligence Scale-Revised (WAIS-R). The subscales and subtests, and their potential selectivity were examined in preclinical HD (30 mutation carriers and 34 noncarriers) with no motor or neuropsychiatric signs of HD.


METHODS
The predicted age of onset in mutation carriers was calculated by a regression equation allowing this group to be divided according to whether onset was predicted as within 12 years (HD+CLOSE) or longer than this (HD+DISTANT).


RESULTS
The HD+CLOSE group scored significantly lower on Verbal, Performance, and Full Scale IQ compared to noncarriers and performed significantly lower on 7 of the 11 WAIS-R subtests, with low average scores in language abilities, attention, abstract thinking, problem solving, visuospatial ability, and psychomotor speed.


CONCLUSIONS
These low average scores affect general intelligence and functioning of HD+CLOSE carriers and are likely to reflect dysfunction of frontal cortex and frontostriatal circuits more than a decade before manifest symptoms. Our findings support a continuous linear model of slow cognitive decline in HD.
Robins Wahlin
Tarja-Brita
TB
Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
Larsson
Maria U
MU
Luszcz
Mary A
MA
Byrne
Gerard J
GJ
D000328:Adult; D001288:Attention; D003072:Cognition Disorders / Q000209:etiology; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000175:diagnosis* / Q000523:psychology*; D007360:Intelligence; D007802:Language; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011340:Problem Solving; D011597:Psychomotor Performance; D013028:Space Perception; D013850:Thinking; D013997:Time Factors; D014796:Visual Perception; D014888:Wechsler Scales