Prediction of dementia by subjective memory impairment: effects of severity and temporal association with cognitive impairment.

TLDR: The prediction of dementia in AD by SMI with subsequent amnestic MCI supports the model of a consecutive 3-stage clinical manifestation of AD from SMI via MCI to dementia.

Abstract: Context Subjective memory impairment (SMI) is receiving increasing attention as a pre-mild cognitive impairment (MCI) condition in the course of the clinical manifestation of Alzheimer disease (AD). Objectives To determine the risk for conversion to any dementia, dementia in AD, or vascular dementia by SMI, graded by the level of SMI-related worry and by the temporal association of SMI and subsequent MCI. Design Longitudinal cohort study with follow-up examinations at 1½ and 3 years after baseline. Setting Primary care medical record registry sample. Participants A total of 2415 subjects without cognitive impairment 75 years or older in the German Study on Aging, Cognition and Dementia in Primary Care Patients. Main Outcome Measures Conversion to any dementia, dementia in AD, or vascular dementia at follow-up 1 or follow-up 2 predicted by SMI with or without worry at baseline and at follow-up 2 predicted by different courses of SMI at baseline and MCI at follow-up 1. Results In the first analysis, SMI with worry at baseline was associated with greatest risk for conversion to any dementia (hazard ratio [HR], 3.53; 95% confidence interval [CI], 2.07-6.03) or dementia in AD (6.54; 2.82-15.20) at follow-up 1 or follow-up 2. The sensitivity was 69.0% and the specificity was 74.3% conversion to dementia in AD. In the second analysis, SMI at baseline and MCI at follow-up 1 were associated with greatest risk for conversion to any dementia (odds ratio [OR], 8.92; 95% CI, 3.69-21.60) or dementia in AD (19.33; 5.29-70.81) at follow-up 2. Furthermore, SMI at baseline and amnestic MCI at follow-up 1 increased the risk for conversion to any dementia (OR, 29.24; 95% CI, 8.75-97.78) or dementia in AD (60.28; 12.23-297.10), with a sensitivity of 66.7% and a specificity of 98.3% for conversion to dementia in AD. Conclusion The prediction of dementia in AD by SMI with subsequent amnestic MCI supports the model of a consecutive 3-stage clinical manifestation of AD from SMI via MCI to dementia.