Synapse density related to cerebral blood flow and symptomatology in frontal lobe degeneration and Alzheimer's disease

In order to evaluate the functional significance of synaptic pathology, syn aptic density was quantitated and related to clinical symptomatology and re gional cerebral blood flow (rCBF) in 8 patients with frontal robe degenerat ion of non-Alzheimer type (FLD) and 19 patients with Alzheimer's disease (A D), Synaptic density was measured in all layers of prefrontal and parietal cortex. The clinical picture of FLD was dominated by a frontal lobe syndrom e with changes in personality and behavior, while AD was dominated by tempo roparietal symptoms. This parallels the finding of frontal rCBF reductions in FLD patients and temporoparietal reductions in AD patients. Synaptic den sity was significantly decreased in both FLD and AD, with a regional severi ty which closely correlated with that of the degeneration, symptomatology a nd rCBF deficit. The results suggest that synaptic pathology is a likely ca use of clinical symptoms and regional metabolic decrement in dementia.