Richard Comshaw, PhD
“Validation of the Alzheimer’s Disease Behavior Scale – Nursing Home”
Abstract: A number of instruments are currently used to diagnose Alzheimer’s Disease. These instruments however, do not adequately assess behavioral changes of Alzheimer’s Disease patients. These shortcomings limit the ability to assess the behaviors faced by the caregivers of Alzheimer’s Disease patients on a daily basis. The purpose of this study was to provide evidence to support the validity of the Alzheimer’s Disease Behavior Scale – Nursing Home (ADBS-NH), a behavior based caregiver report designed to be sensitive and specific to Alzheimer’s Disease. Content validity was performed using a convenience panel of experts in geriatric psychiatry. Thirty persons were then recruited for each of the following known five groups: depressed, vascular dementia, mild Alzheimer’s Disease, moderate to severe Alzheimer’s Disease, and normal controls. The group assignments were determined by the Geriatric Depression Scale, Mini Mental State Examination and Hachinski scores. It was then determined that the most appropriate cutoff score was 25 for this sample as this maximized the sensitivity and specificity. The study then analyzed the construct validity using oblique rotated factor analysis. The results deviated significantly from the expected dimensions that were agreed upon by the content experts. The derived factors named were based upon the items that loaded into each dimension. The dimension names were created using a common language, to make it user friendly to both health care professionals and non-professionals. The concurrent validity of the ADBS-NH was then evaluated and found to be satisfactory. Convergent and discriminate validity was then analyzed. The ADBS-NH correlated poorly with the Hachinski Ischemic Scale and the Geriatric Depression Scale in all groups. It correlated well with the MMSE in both Alzheimer’s Disease groups. These correlations prove that the ADBS-NH did not measure the same dimensions that the Hachinski Ischemic Scale and the Geriatric Depression Scale measured. The ADBS-NH did correlate well with the MMSE in Alzheimer’s Disease groups, which was expected, as both instruments measured the cognitive deficits of Alzheimer’s Disease. Internal consistency reliability was assessed using Cronbach’s Alpha, which was acceptable at .86. Two week stability reliability was evaluated and found to possess a satisfactory stability at .98.