Assessing intellectual deterioration.

Twenty patients fulfilling the clinical criteria of Alzheimer-type dementia were assessed on the Wechsler Adult Intelligence Scale (WAIS), the Schonell Graded Word Reading Test (SGWRT) and the National Adult Reading Test (NART). Fifteen normal elderly control subjects were administered the WAIS and the NART. The regression equations of Nelson & McKenna (1975) and the tables of Nelson (1982) were used to estimate premorbid Full Scale IQ on the basis of WAIS Vocabulary subtest score and performance on each of the reading tests. The data were analysed in order to assess the relative utility of these methods, and of WAIS Verbal-Performance IQ discrepancy, in the assessment of intellectual deterioration. The data suggested that performance on the NART was the best indicator of premorbid level of functioning in terms of the size of predicted-obtained discrepancies.