Hemorheological disturbances and cognitive function in patients with cerebrovascular disease

The aim of the study was to follow the relationship of the hemorheological variables with the cognitive functions in patients with ischemic cerebrovascular disease (CVD). The patient material comprised 117 patients with CVD, distributed in two main groups: 44 with transient ischemic attacks (TIAs) and 73 with chronic cerebral infarctions (CCI), 48 of them being unilateral (UCI) and 25 bilateral (BCI). Additional relative distribution according to the mean arterial blood pressure (MABP) values or to the presence of pathological asymmetries of the hemispheric cerebral blood flow (CBF) was made. The main hemorheological variables: hematocrit (Ht), fibrinogen (Fib) and plasma viscosity (PV) were examined. The cognitive functions were assessed with a psychological test battery for evaluation of the general cognitive state, the nonverbal intellect, the episodic memory, the selective attention and the executive functions. The hemorheological investigation revealed predominant increase of PV. The results of all neuropsychological tests showed significant impairment in the patients with CCI in comparison to TIAs. Fibrinogen correlated best with the psychological parameters. Its increase was associated with disturbance of the nonverbal intellect and the general cognitive capacity in the patients with CCI and BCI. In the presence of lower MABP or lack of pathological asymmetries the correlations of Fib and PV with the psychological scores predominated. The results of our study reveal distinct association between the blood rheological properties and the cognitive functions in the patients with ischemic CVD, which is probably based not only on vascular but also on other nonvascular mechanisms.