LOWER PLATELET COUNT AND DECREASED MEAN PLATELET VOLUME IN PATIENTS WITH ALZHEIMER’S DISEASE

Abstract

Platelets are the major players in hemostasis, but are also involved in thrombosis, inflammation and tissue repair. Platelets are generally accepted as a suitable model for Alzheimer's disease (AD). In the present study serum platelet count, mean platelet volume (MPV), platelet distribution width (PDW) and plateletcrit (PCT) in patients with Alzheimer disease were analyzed and compared with controls. Platelet count and indices were evaluated in 130 patients with AD (Mean age 71.3±7.7 years, range 55–85 years, 65 women), (DSM-IV; NINCDS-ADRDA criteria); recruited in a community elderly in Skikda-Algeria (2016-2018); and in 130 elderly controls, (Mean age 69.8±7.8 years, range 55–85 years, 65 women). We assessed the relation between these platelet parameters and the odds ratio (OR) for AD. Correlation with dementia severity (Clinical dementia rating-global score, and mini mental status examination), was also examined. The mean serum platelet count was 220.5±44.7x109/L (Range 148x109-354x109) among cases, and 240.1±49.9x109/L (Range 155x109-396x109) among controls, (p= 0.0009). By gender, the difference between cases and controls was significant both in men 218.3±50.2x 109/L vs. 236.8±52.4x109/L respectively, p=0.041; and in women 222.7±38.7x109/L vs. 243.4±47.4x109/L, p= 0.007. The odds ratio [95 percent confidence interval] of AD for the highest tertile of platelet count compared to the lowest tertile was 0.428 [0.234–0.782], p= 0.006. This association was significant both in men OR: 0.3175 [0.1316–0.7659], p=0.017, and in women OR: 0.2663 [0.1102–0.6440], p=0.003. MPV was significantly lower in men cases compared to controls 9.04±0.8 femtoliter (Range 7.3-11.4) vs.9.34±0.9 femtoliter (Range 7.8-11.6) respectively; p=0.045. Mean plateletcrit was decreased in AD group compared to control 0.202±0.03% (Range 0.120-0.324) vs. 0.216±0.05% (Range 0.129-0.360), p=0.003. PDW was similar, AD: 13.2±1.2%, control: 13.4±1.5%. Platelet count and indices did not correlate significantly with dementia severity. These findings show that Alzheimer's disease patients have lower platelet count and lower plateletcrit (Within normal range) compared to controls. Subjects in the low normal range of platelet count have an increased risk for developing Alzheimer's disease. Furthermore a lower MPV (within normal range) was also found in AD men. Taken together, these data suggest a key role for circulating platelets in Alzheimer's disease.