PLATELET OF ALZHEIMER PATIENTS - INCREASED COUNTS AND SUBNORMAL UPTAKE AND ACCUMULATION OF [C-14] 5-HYDROXYTRYPTAMINE

Platelets are the main source of 5-hydroxytryptamine (5-HT) and amyloi d precursor protein (APP) found in plasma. We studied a possible corre lation between platelet markers and the clinical diagnosis of Alzheime r disease (AD). Our results indicate that in AD patients: (a) platelet s are elevated, (b) their ability to accumulate 5-HT decreases and, (c ) the kinetic parameters of 5-HT uptake are altered (decreased K-m and V-max), compared to non-demented healthy individuals. An aged Down sy ndrome patient presents even more deviant alterations. Our finding sup ports the idea that platelets may provide a systemic marker of AD, and eventually be useful for the clinical diagnosis of the disease.