Patterns of glial cell activity in fronto-temporal dementia (lobar atrophy).

Fronto-temporal dementia is a clinical syndrome with a number of pathological substrates, including frontal lobe degeneration, Pick's disease, and motor neuron disease with dementia; it also includes patients with a primary progressive language disorder. Twenty-four brains were examined, using immunohistochemistry for glial fibrillary acidic protein (GFAP) and ferritin. Five cases of fronto-temporal dementia with a Pick's disease type of histology showed marked cortical gliosis with striking microglial activity in both grey and white matter. In seven cases of frontal lobe degeneration, there was little gliosis and microglial activity was confined largely to the white matter; two of the seven cases of progressive language disorder showed similar changes to frontal lobe degeneration. Five cases of motor neuron disease with dementia showed both astrocytic and microglial activity within the white matter. We suggest that cases of fronto-temporal dementia due to Pick type histology may result from a process which primarily involves grey matter, whereas cases of frontal lobe degeneration might represent a disorder of white matter.