Diagnosing Alzheimer's disease in very elderly patients. Relevance of some functional and psychobehavioral aspects assessed by the Gottfries-Bråne-Steen Rating Scale for Dementia. Study Group on Brain Aging, Italian Society of Gerontology and Geriatrics

Abstract

Objectives: To describe the Gottfries-Bråne-Steen (GBS) Rating Scale more fully with instruments commonly used for the diagnostic assessment of older patients with cognitive disturbances--the Mini Mental State Examination (MMSE), Hamilton Depression Rating Scale (HDRS), and Global Deterioration Scale (GDS)--and to characterize the specific diagnostic value of the GBS.

Design: A multicenter study including patients diagnosed with senile dementia of the Alzheimer type (SDAT; age at onset: > 75 years) and age-matched non-demented subjects.

Subjects: One hundred thirty-eight consecutively referred SDAT patients and 116 non-demented age-matched healthy subjects selected from among relatives of the patients.

Methods: The MMSE, GBS and HDRS were used for assessing patients and controls. The GDS was utilized for dementia staging.

Findings: Principal component analysis carried out on GBS scores yielded three factors explaining 74% of variance: factor 1, general functioning; factor 2, depression, and factor 3, restlessness. The actual composition of these factors was analyzed after computing factor scores for each subject by means of forward selection regressions, each using the MMSE, GDS and HDRS as predictors of scores on a given factor. The best predictors were MMSE and GDS scores for factor 1; HDRS for factor 2, and MMSE for factor 3. A GBS cutoff of 8 (obtained after a quality receiver operating characteristic analysis) best discriminated between demented and non-demented subjects (positive-predictive value: 0.88; negative-predictive value: 0.90).

Conclusions: The GBS Rating Scale for dementia can be a useful tool in routine clinical assessment of older subjects with cognitive impairment and distinguishes between demented and non-demented subjects; it gives comprehensive information on functional and psychobehavioral characteristics of demented patients, being composed of factors related to the MMSE and HDRS.