Objective: To rate magnetic resonance image signal hyperintensities in clearly defined white and deep gray matter areas in patients with early Alzheimer's disease and controls.
Design: Prospective series. The National Institute for Neurological Disorders and Stroke--The Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease. Blinded assessment.
Setting: University hospital, dementia study group.
Subjects: Thirty-four patients with Alzheimer's disease. Thirty-eight age-matched healthy community volunteers.
Measures: Frequency of hyperintensities in axial magnetic resonance images (1.5-T system) seen both in the proton density and T2-weighted scans examined in vascular centrencephalon, centrum semiovale, watershed, periventricular, and subcortical white matter. Periventricular hyperintensities classification include caps, thin lining, and smooth and irregular halo. Hyperintensities in other areas include small and large focal, focal confluent, and diffusely confluent. The hyperintensities were counted and rated using a five-point scale and the Fazekas method.
Results: No difference in the ratings, frequency, or extent of the hyperintensities between patients with early Alzheimer's disease and controls. Majority of patients and controls had two or fewer hyperintensities and they were mostly small foci, caps, and thin linings. The hyperintensities are associated with arterial hypertension, diabetes, cardiac disorder, and age in different combinations, but not with Alzheimer's disease.
Conclusion: Tiny hyperintensities on magnetic resonance images are frequent both in patients with early Alzheimer's disease and in healthy controls; most of the lesions are not related to brain ischemia. When age and vascular risk factors were taken into account, no difference between patients with early Alzheimer's disease and control subjects could be detected.