The Impact of Non-Reading Language Performance on the Estimation of Premorbid IQ among Normal Elderly Individuals

The influence of non-reading language ability was studied in the context of estimating premorbid IQ among normal elderly individuals. Non-reading language performance was measured by the Controlled Oral Word Association (COWA) Test and the Animal Naming (AN) Test. Non-reading language disturbances were divided into three levels (i.e., no disturbance on COWA and AN, either COWA or AN disturbance, and both COWA and AN disturbances). Intellectual ability was primarily measured by the Wechsler Abbreviated Scale of Intelligence (WASI). Additionally, reading measures such as the New Adult Reading Test- Revised (NART-R) and the Wide Range Achievement Test- Fourth Edition (WRAT-4) Word Reading subtest were used to predict premorbid intellectual ability. Results indicated that the scores on the WASI Full Scale IQ (FSIQ), NART-R estimated FSIQ, and WRAT-4 Word Reading subtest decreased when the severity of the non-reading language disturbances increased. Results also suggested that non-reading language performance did not predict intellectual ability across the three levels of disturbances. Instead, the NART-R was found to account for more variance in WASI FSIQ scores when there were no non-reading language disturbances (83.4%) and COWA or AN disturbance (52.4%). The WRAT-4 Word Reading subtest was found to account for more variance (84.1%) in WASI FSIQ scores when there were disturbances on both COWA and AN. Limitations of the study, directions for future research, and diversity issues were also addressed.