Estimating verbal intelligence in unipolar depression: comparison of word definition and word recognition

Depression is known to be associated with deficits in effortful processing and word fluency. Automatic processes, instead, appear largely intact in depressed patients. It was investigated whether active word definition could be a less appropriate method than passive word recognition as a measure of verbal intelligence in depression. The valid assessment of premorbid IQ is important for correct comparison with current cognitive efficiency of depressed individuals, since premorbid IQ serves as baseline or control parameter to estimate the extent and severity of acquired cognitive impairments, both in the clinical and the research context. Two vocabulary tests were administered to 90 patients (31 women) with unipolar depression and 30 control subjects (15 women): a word definition task [the vocabulary subtest of the Wechsler Adult Intelligence Scale (WAIS-R)] and a word recognition task [the Multiple choice vocabulary test (MWT)]. In the depressed sample, scores of the MWT tended to be higher than WAIS-R scores. For depressed women, the MWT score was significantly higher than the WAIS-R score. In the control sample, no differences between MWT and WAIS-R scores were observed. Our findings indicate that word definition tasks could underestimate verbal intelligence especially in depressed women. For depressed women, it could be more appropriate to administer word recognition than word definition as an estimate of premorbid or verbal intelligence.