Dementia is an illness that affects an estimated 10% of noninstitution
alized persons older than 65 years of age. Among those older than 85 y
ears of age, dementia is estimated to affect 20 to 50% of the populati
on. The diagnosis of Alzheimer's disease is based on clinical criteria
and the exclusion of other causes of dementia. Neuroimaging procedure
s, mostly CT scans, have been used to exclude other lesions presenting
as dementia. The yield of these procedures has been estimated to be a
bout 3%. This article reviews some of the literature on this topic in
an effort to establish specific recommendations or neuroimaging proced
ures in patients who present with dementia.