Evidence highlights potential hypertension-cognitive decline link in elderly population
Increasing evidence points to a link between hypertension and cognitive decline, particularly in the elderly population, according to a presentation at the recent Asian-Pacific Congress of Hypertension (APCH 2017). However, the impact of antihypertensive medication use on dementia incidence is unestablished.
“[There is] accumulating evidence that hypertension may contribute to the development of both Alzheimer’s disease and vascular dementia,” said Dr Yuda Turana from the Atma Jaya Catholic University of Indonesia, who highlighted several studies that point to this link. The association between hypertension and cognitive decline is via white matter lesions, he said. [APCH 2017, Symposium F]
A meta-analysis of 11 studies comprising 768 individuals with vascular dementia and 9,857 controls found a significant association between hypertension and the risk of incident (odds ratio [OR], 1.59; p<0.0001) and prevalent vascular dementia (OR, 4.84; p<0.00001). [Int J Geriatr Psychiatry 2011;26:661-669]
Another study of 1,352 individuals found that hypertension in midlife was linked to an acceleration of white matter hyperintensity volume progression (p<0.001) as well as a decline in executive function (p=0.012). [Neurology 2011;77:461-468]
In a study involving 668 Japanese elderly individuals (aged 65–79 years) who were followed up for 17 years, during which 76 and 123 individuals developed vascular dementia and Alzheimer’s disease, respectively, hypertension was associated with an elevated risk of vascular dementia compared with those with normal blood pressure (3.0-, 4.5-, and 5.6-fold risk with prehypertension, stage 1, and stage 2 hypertension, respectively). However, there was no link observed between hypertension and Alzheimer’s disease risk. [Hypertension 2011;58:22-28]
Similarly, a meta-analysis of nine studies comprising 15,292 patients showed no difference in the incidence of Alzheimer’s disease between patients with and without hypertension (relative risk [RR], 1.02). Use of antihypertensive medications also had no impact on Alzheimer’s disease incidence (seven studies, n=21,744, RR, 0.90). [J Alzheimer’s Dis 2011;27:799-807]
Evidence on the role of antihypertensive medications in the reduction of dementia is conflicting. For example, the Syst-Eur* study suggested that treating hypertension with a calcium channel blocker (CCB) conferred a potential protective effect against dementia, particularly Alzheimer’s disease, while the PROGRESS** study suggested that angiotensin-converting enzyme inhibitors, with or without diuretics, may reduce the incidence of dementia due to stroke but not in non-stroke-related dementia.
Conversely, the SHEP*** trial which involved the use of a chlorthalidone-based antihypertensive regimen, the SCOPE# study which used the angiotensin II receptor blocker (ARB) candesartan or hydrochlorothiazide, and the HYVET-COG## study which used indapamide or perindopril did not demonstrate an impact on dementia.
However, a meta-analysis of the Syst-Eur, PROGRESS, SHEP, and HYVET-COG trials demonstrated an association between antihypertensive therapy and reduced risk of dementia, while a study which included the results of Syst-Eur, SHEP, and SCOPE showed no association between antihypertensive therapy and reduced risk of dementia. [Int J Hypertens 2012;2012:320648]
A more recent study has postulated that the protective effect conferred by antihypertensive medications may be class-related, where among 1,951 patients, the use of CCBs and ARBs were associated with a reduced dementia risk (hazard ratio, 0.56 and 0.60, respectively). [J Hypertens 2017:35:2095-2101]
Antihypertensive treatment appears to significantly reduce the risk of dementia, though there is still some controversy over this,. said Turana.