Regional cerebral blood flow and prognostic evaluation in Alzheimer's disease

The present investigation reports the application of regional cerebral blood flow (rCBF; 133Xe method) to prognostic purposes in a consecutive series of 76 patients (mean age 68.4 ± 8.7 years) with probable Alzheimer's disease (AD; NINCDS-ADRDA criteria). The likelihood that rCBF from a posterior temporal-inferior parietal area in each hemisphere at the first visit may predict timing of achievement of three endpoints (i.e. loss of activity of daily living, ADL, incontinence and death due to end-stage AD) was tested by the 'lifereg' procedure of the Statistical Analysis System package. With respect to baseline evaluation, 32 patients lost ADL 20.6 ± 17.4 months later, 31 developed incontinence 27.1 ± 19.0 months later, and 16 patients died after 40.9 ± 23.8 months of follow-up. Baseline rCBF significantly predicted all end-points: the loss of ADL (left hemisphere: p = 0.04; righth hemisphere: p = 0.02), incontinence (p = 0.02 in both hemispheres) and death (p = 0.01 in both hemispheres). Statistical significance was maintained for the loss of ADL and incontinence both in a subgroup of mildly demented patients, in whom death was not considered due to the low number of patients who died, and in a multivariate analysis including patient age, age at onset, sex, duration of illness, Mini-Mental State Examination score and presence of extrapyramidal signs and psychotic symptoms at the first visit. This study shows that rCBF measurement in a posterior temporal-inferior parietal area may give prognostic information on timing of evolution of AD, whenever performed during the course of the disease, and may be utilized both in clinical practice and for social planning.