Clinical Manifestations.

Area of Science:

• Gerontology
• Neurology
• Clinical Medicine

Background:

• Previous research proposed disease staging for mild cognitive impairment (MCI) and Alzheimer's dementia (AD) using the Lawton-Brody Instrumental Activities of Daily Living Scale (IADL).
• A crosswalk was established between the IADL and the Mini-Mental State Examination (MMSE) for staging.
• This study aimed to estimate disease trajectory using proposed IADL cut-off scores for Alzheimer's disease stages.

Purpose of the Study:

• To estimate disease trajectory in patients with MCI or AD based on proposed IADL stage cut-off scores.
• To analyze disease stage transition over time using statistical modeling.
• To provide an alternative measure of disease progression using IADL scores.

Main Methods:

• Patients diagnosed with MCI or AD were identified from the US Veteran's Affairs Healthcare System administrative database (2016-2024).
• IADL cut-offs were derived using linear least squares means, defining stages for normal, MCI, mild, moderate, and severe disease.
• Mixed effects statistical modeling was employed to estimate disease stage transition over time, controlling for demographics and allowing for nonlinear trends.

Main Results:

• The study included 90,114 patients (mean age 80.2 years; 97.5% men).
• Estimated transition times from MCI to severe stages were approximately 13 years.
• Estimated transition times from AD to severe stages were approximately 9 years.

Conclusions:

• Functional deterioration in Alzheimer's dementia and mild cognitive impairment progresses to severe stages within 9 and 13 years, respectively.
• Trajectory estimations using IADL provide a valuable measure of functional decline corresponding to cognitive deterioration.
• The IADL scale is a broadly used assessment in clinical practice for evaluating functional decline in neurodegenerative diseases.