Time-sparing screening method for mild cognitive impairment and early Alzheimer's disease: Self- and family reports using the TMIG index of competence

Abstract

To verify the clinical utility of instrumental activities of daily life evaluated using the Tokyo Metropolitan Institute of Gerontology index of competence (TMIG-IC) as a screening tool for patients with early-phase cognitive impairment, including mild cognitive impairment (MCI) and early Alzheimer's disease (AD). We recruited healthy subjects from our community-based cohort and consecutive subjects with MCI and AD from our clinic. The TMIG-IC was investigated in all participants and their family members. The total and subscale scores were compared among all groups. We then statistically determined the accuracy of the differentiation of MCI and AD. We registered 187 normal controls (NC), 39 participants with MCI, 50 AD patients with functional assessment staging (FAST) 4, and 19 AD patients with ≥5 FAST. The family-report score was significantly lower in MCI patients than in others, followed by AD patients. The total score was able to differentiate MCI and AD with a sensitivity of 85.7% and a specificity of 90.9% (area under the curve [AUC]=0.913). Differentiation of MCI alone had a low accuracy (AUC=0.787). However, the AUC was 0.847 when only the items with inconsistent responses between self and family reports were used as indices. The TMIG-IC is a useful tool for evaluating the severity of AD, including early AD. These findings suggest that family-report scores can differentiate MCI and AD from cognitive normal aging with a sufficient degree of accuracy. It was also suggested that inconsistencies between self and family reports were higher when differentiating MCI than the self- and family-reports.