The Japanese Version of 26-Item Informant Questionnaire on Cognitive Decline in the Elderly: Development and...

Area of Science:

• Gerontology
• Neurology
• Psychometrics

Background:

• Dementia detection relies on accurate cognitive assessment tools.
• Informant-based questionnaires offer a valuable perspective on cognitive changes.
• Validating international tools for local populations is crucial for accurate diagnosis.

Purpose of the Study:

• To develop and validate the Japanese version of the 26-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-J).
• To assess the diagnostic accuracy and concurrent validity of the IQCODE-J for detecting dementia in Japanese outpatients.

Main Methods:

• A cross-sectional study involving 166 outpatients at a university memory clinic.
• Participants' informants completed the IQCODE-J; dementia diagnosis followed DSM-5 criteria.
• Diagnostic accuracy was evaluated using receiver operating characteristic analysis and bootstrap validation.
• Concurrent validity was assessed through correlations with other cognitive and dementia rating scales.

Main Results:

• The IQCODE-J demonstrated higher scores in the dementia group (p < 0.001).
• An optimism-corrected area under the curve of 0.74 was observed.
• A cut-off score around 4.0 showed a specificity of 81.8% and sensitivity of 47.5% in bootstrap validation.
• The IQCODE-J showed significant correlations with AD8-J, CDR-J, MMSE-J, and FAB (all p < 0.001).

Conclusions:

• The IQCODE-J is a valid and feasible informant-based tool for assessing cognitive decline in Japanese patients.
• A practical cut-off score of approximately 4.0 is suggested when prioritizing specificity in referral settings.