PSYCHOMETRIC EVALUATION OF A MEASURE OF COGNITIVE DECLINE IN ELDERLY PEOPLE WITH MENTAL-RETARDATION

Forty elderly persons with mental retardation were assessed by their c are providers on a modified version of the Short Informant Questionnai re on Cognitive Decline in The Elderly (IQCODE), an instrument designe d to quantify cognitive decline in elderly people in the general popul ation. They were also assessed for IQ, aberrant behavior, and current mental status; test-retest and interrater reliability were evaluated a s well. Internal consistency, as assessed by coefficient alpha, was mo derately high (alpha = .86). Test-retest reliability was mediocre and interrater reliability levels did nor reach statistical significance. The Short IQCODE was riot correlated with a variety of demographic fea tures or with behavior ratings, showing evidence of divergent validity . However, the Short IQCODE was only weakly (nonsignificantly) correla ted with a measure of current mental status, which challenges its conc urrent validity. The Short IQCODE probably needs to be modified furthe r for satisfactory psychometric performance in people with mental reta rdation. However, some features of this study may have resulted in sub optimal estimates of the Short IQCODE's psychometric characteristics. (C) 1998 Elsevier Science Ltd.