Cognitive decline: the relevance of diabetes, hyperlipidaemia and hypertension

Abstract

Cognitive decline including mild cognitive impairment describes a heterogeneous condition with cognitive changes between normal ageing and dementia. Cognitive impairment can be promoted or caused by treatable somatic factors. In this review, three important cardiovascular risk factors, diabetes mellitus, hypercholesterolaemia and hypertension, and their association with cognitive decline, are assessed. Though there are many hints of a causal association between diabetes mellitus and the development of cognitive decline, definitive proof of a protective effect of antidiabetic treatment by controlled or randomised placebo-controlled studies is needed. In midlife, elevated cholesterol levels comprise a risk factor for cognitive decline. In elderly subjects, cholesterol levels decline and are not clearly associated with cognitive impairment. The evidence for treatment of hypercholesterolaemia by statins solely for prevention of cognitive decline remains unclear. There is an age-dependent relationship between blood pressure and cognitive impairment. Midlife hypertension is associated with an increased risk of developing cognitive decline and antihypertensive treatment may therefore be beneficial, whereas hypertension later in life does not carry the same risk of cognitive dysfunction. Diagnosis of these somatic factors is essential in cognitive impairment, as diligent treatment may improve cognitive performance and postpone the manifestation of dementia.