[Psychometric study of the vocabulary of older and very old adults].

Sixty-five non-demented elderly adults, born between 1895 and 1918 (mean age +/- SD: 80.0 +/- 5.4) were tested with the Vocabulary Test of the 1970 Dutch revision (30-item form) of Wechsler's Adult Intelligence Scale. Subjects were recruited from homes for the aged and were rated by the staff as free from any symptoms of dementia or other psychiatric disease. Vocabulary scores ranged from 11 to 53 (maximum score would be 60) with mean +/- SD of 31.3 +/- 10.2 Subjects who had received more formal education performed better on this test (Pearson's r = 0.59). When education was controlled for in the analysis, the correlation between age and performance was attenuated and did not reach statistical significance (Pearson's r = -0.16). Data are presented for two levels of education that can be used to put clinical data in perspective. The level of difficulty of each item of the Vocabulary scale was calculated for this sample. Twelve per cent of the subjects recorded correct answers beyond the official criterion of five consecutive failures for discontinuing the test. The effect of differences in item difficulty could be minimized by using a criterion of six consecutive failures to determine the point at which the test should be discontinued.