Vascular risk factors and lipoprotein(a) levels in the differential diagnosis of dementias

Several vascular risk factors, including lipoprotein(a) (Lp(a)) levels, and its apo(a) isoforms were evaluated in 104 consecutively hospitalized demented patients, with the aim of comparing their prevalence in dementias of different etiology. The sample included 67 vascular dementias (VD), 29 senile dementias of Alzheimer's type (SDAT), and 8 hemorrhagic dementias (HD). The NINDS-AIREN and NINCDS/ADRDA criteria were used for the diagnosis. Hypertension, and signs of left ventricular hypertrophy (LVH) were more frequent in VD and HD, than in SDAT, and were positively associated with cortical-subcortical infarction; signs of LVH were also associated with leukoaraiosis. Demented patients had lower total cholesterol (TC) and high density lipoprotein-C (HDL-C) levels than controls. No differences in serum lipids emerged between the 3 demented groups. Median Lp(a) was higher in VD, as compared to SDAT and controls, and in patients with lacunar infarctions. Lp(a) higher than 30 mg/dl was more frequent in VD than in SDAT and controls. Apo(a) S1 isoforms were significantly more frequent in VD than in SDAT + HD; isoforms heavier than S4 were more frequent in HD than in VD and SDAT. The Hachinski ischemic score (HIS) was positively correlated with Lp(a) levels (Spearman Rho = 0.23, p < 0.038). A HIS greater than or equal to 7, hypertension, and high Lp(a) levels discriminated VD from SDAT with a sensitivity of 80, 76 and 40 %. and a specificity of 90, 57 and 76 % respectively. We conclude that among the vascular risk factors considered, Lp(a) levels discriminated VD from SDAT with a low sensitivity but a high specificity. Further studies are needed to evaluate the possible routine use of this parameter in the differential diagnosis of dementia.