Antihypertensive treatment and dementia.

Dementia is a syndrome of global cognitive de­ cline which inter venes with social and occupation­ al functioning. The two most common dementias are Alzheimer's disease (AD), caused by neuro­ degeneration, and vascular dementia, caused by cerebrovascular disease. These two causes often co­occur (often referred to as " mixed dementia "), especially after the age of 80. Dementia is com­ mon in the elderly and constitutes one of the larg­ est burdens for individuals and society. Its preva­ lence increases from around 3% at the age of 70 to 30% at the age of 85. It can be expected that the number of demented in the world will increase from less than 40 million in 2005 to more than 130 million in 2050, mainly due to an increasing number of elderly individuals, especially those aged >80 years. It is therefore important to find ways of preventing dementia. Since the mid 1990s, a large number of obser­ vational studies have reported an association between previous high blood pressure and later development of dementia, including Alzheim­ er's disease. 1,2,3 High mid­life blood pressure has also been related to the presence of senile plaques and neurofibrillary tangles, the hallmarks of AD in the brain, in late life. 4 At the same time, obser­ vational population studies suggest that the use of antihypertensive drugs may reduce the inci­ dence of AD and dementia. 2,5,6 Furthermore, it is reported that previous high blood pressure is only related to late­life dementia in those not on antihypertensive treatment. 3 Five antihypertensive trials with dementia as secondary end­points have been conducted. 7‑12 All these trials observed significant reductions in the primary cardiovascular outcomes, but only the Syst­Eur (Systolic Hypertension in Eu­ rope) trial 8 reported a reduction in the incidence of dementia in the treatment group. However, only 32 persons developed dementia in this trial. In the SCOPE trial, a secondary analysis showed that the treatment group had less cognitive de­ cline than the placebo group among those with mild cognitive impairment at baseline. 9 The first trials were mainly conducted among individuals aged <80 years, where risk for dementia is low. 12 Last year, results from HYVET (The Hyperten­ sion in the Very Elderly Trial) were published. This was a double­blind placebo controlled study conducted on patients aged ≥80 who had systol­ ic hypertension. 13 In this age group, dementia in­ cidence is very high. The HYVET …