The age at onset of Alzheimer's disease and an intracranial area measurement. A relationship
P. W. Schofield, R. E. Mosesson, Y. Stern and R. Mayeux
Gertrude H. Sergievsky Center, Columbia University, New York, NY.
OBJECTIVE: To examine the possibility that premorbid brain size may
influence the age at onset of symptoms of Alzheimer's disease (AD). DESIGN:
Retrospective case series. SETTING: Outpatients attending a memory
disorders clinic in a tertiary referral center. PATIENTS: Twenty-eight
female patients with the diagnosis of probable AD, selected for the
availability of informant derived estimates of age at onset of symptoms and
computed tomographic scans of the head satisfying angulation criteria. MAIN
OUTCOME MEASURE: An average intracranial area of two adjacent computed
tomographic scan sections appropriately angled was used as a correlate of
premorbid brain size. Strict intracranial volume measurement was not
performed. RESULTS: Age at onset of symptoms of AD correlated positively (r
= .48, P = .009) with our measure of premorbid brain size. There was no
confounding by education, height, or ethnicity. CONCLUSION: Premorbid brain
size may be an important determinant of the age at onset of symptoms of AD.
Epidemiologic studies of AD may need to assess the relationship between
brain size and putative risk factors, eg, low educational attainment, since
there is evidence that brain size is not distributed uniformly across
populations.