Thalamic and subcortical gliosis with dementia.

We describe two cases of patients with "primary dementia" in whom autopsy showed marked astrocytosis in several subcortical nuclei, but chiefly in those of the thalamus. One patient had the onset of symptoms at 31 years of age and a subacute course. The second patient was an elderly man with a strong familial history of dementia. These cases offer further evidence that subcortical lesions, especially in the thalamus, may produce a dementia that is not always clinically distinguishable from Alzheimer's disease and other "cortical" dementias.