The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): socio-demographic correlates, reliability, validity and some norms

Abstract

SYNOPSISThe IQCODE is a questionnaire which asks an informant about changes in an elderly person's everyday cognitive function. The questionnaire aims to assess cognitive decline independent of pre-morbid ability. In the present study, the IQCODE was administered to a sample of 613 informants from the general population. In addition, the questionnaire was administered to informants of 309 dementing subjects who had filled it out one year previously. A principal components analysis, using the general population sample, confirmed that the IQCODE measures a general factor of cognitive decline. The questionnaire was found to have high internal reliability in the general population sample (alpha = 0-95) and reasonably high test-retest reliability over one year in the dementing sample (r = 0-75). The total IQCODE score, as well as each of the 26-items, was found to discriminate well between the general population and dementing samples. The correlation with education was quite small (r = -0-13), indicating that contamination by premorbid ability is not a problem.

Everyday functioning in relation to cognitive functioning and neuroimaging in community-dwelling Hispanic and Non-Hispanic older adults

“…Functional assessment-Change in everyday behavior associated with cognitive decline was assessed using the IQCODE (Jorm et al, 1991;Jorm & Jacomb, 1989;Jorm & Korten, 1988). This is a 26-item interview-based questionnaire completed by an informant familiar with the participant.…”

“…Both the English and Spanish versions of the IQCODE have been published in their entirety elsewhere (Jorm, 1994;Morales et al, 1995). The IQCODE has been shown to have high internal consistency, with alphas ranging from .93 to .95 (Jorm & Jacomb, 1989) and good test-retest reliability, both over a few day period (r = .96) and over 1 year (r = .75) (Jorm & Jacomb, 1989;Jorm et al, 1991). The IQCODE also has limited association with education (Fuh et al, 1995;Jorm & Jacomb, 1989).…”

“…The IQCODE has been shown to have high internal consistency, with alphas ranging from .93 to .95 (Jorm & Jacomb, 1989) and good test-retest reliability, both over a few day period (r = .96) and over 1 year (r = .75) (Jorm & Jacomb, 1989;Jorm et al, 1991). The IQCODE also has limited association with education (Fuh et al, 1995;Jorm & Jacomb, 1989). A number of studies have shown that it is a sensitive indicator of dementia (sensitivity = .86 and specificity = .80) (Jorm, 1997;Jorm et al, 1991;Morales et al, 1997) and correlates with brief cognitive screening measures such as the MMSE (r = −.65) (Flicker et al, 1997).…”

Degree of discrepancy between self and other‐reported everyday functioning by cognitive status: dementia, mild cognitive impairment, and healthy elders

“…The DFQ is a 22-item rating scale assessing an individual's ability to complete everyday cognitive and functional tasks. It was based, in part, on the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE; (Jorm and Jacomb, 1989) but was significantly expanded to sample a wider range of everyday functional changes at both ends of the ability spectrum. A Spanish language version has been created using back-translation methods.…”

“…The IQCODE (Jorm and Korten, 1988;Jorm and Jacomb, 1989;Jorm et al, 1991) was used as a measure of functional change in the determination of clinical diagnosis. This is a 26-item interview-based questionnaire completed by an informant familiar with the participant.…”