CSF silicon in dementia: a prospective study.

We designed a prospective study to determine whether CSF silicon elevation is specific for Alzheimer-type dementia (ATD) and whether it is related to the severity of cognitive or functional impairment. We found elevated CSF silicon in 30% of 23 ATD patients but in only 1 of the 23 age-matched nondemented controls. In all ATD patients with elevated CSF silicon, symptoms began after age 65. Thirty-four percent of 29 patients with other types of dementia also had elevated CSF silicon. Therefore, elevated CSF silicon concentrations are not specific for ATD, but they correlate with age and severity of functional impairment in late-onset ATD.