The influence of vascular risk factors on cognitive decline in patients with dementia: A systematic review

Background and objective: Vascular risk factors (VRF) are associated with a higher incidence of dementia. However, the relationship with disease progression is unclear. This review examined the association of VRF (hypertension, hypercholesterolemia, diabetes mellitus, overweight, smoking or multiple VRF) and cognitive decline in patients suffering from dementia. Methods: Literature was searched in four databases (Pubmed, Embase, Cochrane, PsychInfo) and 1779 articles were identified. This resulted in a total of 20 articles which were included. Results: Twelve studies on hypertension (HT) were inconsistent about the association with cognitive decline. For hypercholesterolemia (HC) 2 (out of 7) studies were associated with increased cognitive decline, as were both (2/2) studies which researched LDL-cholesterol. Articles were inconclusive about the effect of diabetes mellitus (DM): five (out of 13) found less cognitive decline, 2 found more cognitive decline, and 6 found no significant effect of DM. Overweight (BMI >25 kg/m(2)) was associated in 2/4 studies with a slower rate of cognitive decline, while the other 2 studies found no effect. All studies (5/5) that researched smoking did not find a significant effect. Four studies (out of 7) that looked at multiple VRF found faster cognitive decline, and 3/7 found no effect. Discussion: The results of this review suggest an association between LDL-cholesterol and the progression of dementia, while inconsistent results were found for other VRF. Additional prospective cohort studies and experimental studies should be performed to better understand the causal contribution of VRF on cognitive decline in dementia. (C)2013 Elsevier Ireland Ltd. All rights reserved.