Reading ability as an estimator of premorbid intelligence: does it remain stable in emergent dementia?
The 6-year stability of reading performance was investigated in subjects who were normal at baseline but suspect for dementia at follow-up (MMSE score < or = 23; n = 197), and in a cognitively intact control group (n = 117). The Dutch version of the National Adult Reading Test (DART) was used. The DART-based estimate of IQ appeared to be very stable in healthy elderly. In the "suspect" group, the decline after 6 years was about 3 IQ-points in subjects who were still not demented, minimally demented, or mildly demented. Reliability remained satisfactory in these subgroups. In cases with moderate and severe dementia, the decline was considerable (> or = 15 IQ points). The decline of DART IQ was related to deterioration of semantic memory as reflected in verbal abstraction and category fluency. It is concluded that the DART remains a valid estimator of premorbid verbal intelligence in mild and questionable dementia. A formula is presented which can correct the underestimation on the basis of the MMSE score.
Department of Psychiatry, Vrije Universiteit, Amsterdam, The Netherlands.
B
B
Schmand
M I
MI
Geerlings
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C
Jonker
J
J
Lindeboom
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000175:diagnosis* / Q000523:psychology; D004411:Dyslexia, Acquired / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007360:Intelligence; D008297:Male; D008609:Mental Status Schedule; D011932:Reading