A new study has found that people over 60 with untreated high blood pressure have a greatly increased risk of developing dementia compared to those who take blood pressure medication. The findings suggest that maintaining treatment for high blood pressure throughout later life is important for dementia prevention.
The link between hypertension, or high blood pressure, and dementia has been known for years. For those in midlife, studies have found that hypertension can increase the risk of all-cause dementia by around 60%. But for people in later life, study results haven’t been consistent, finding either no association or that hypertension reduces the risk of dementia.
So, researchers from the University of New South Wales, La Trobe University, the George Institute for Global Health and the Australian National University conducted a meta-analysis of 17 studies to ascertain whether blood pressure and treatment for hypertension in those over 60 are associated with dementia risk.
The studies included a total of 34,519 participants without dementia from 16 countries. All participants lived in the community, had a mean age at baseline of 72.5 years, and 58.4% were female. Participants were grouped into three categories based on previous diagnosis of hypertension and baseline use of blood pressure medications (antihypertensives): healthy controls, treated hypertension, and untreated hypertension. The key outcome for the meta-analysis was all-cause dementia.
Covariates included age, sex, educational level, race, BMI, diabetes status, high cholesterol, and smoking status. Race was included because previous studies have found that hypertension is differentially associated with dementia risk in different racial groups.
After analyzing the study data, the researchers found that participants with untreated hypertension had a 42% increased risk of dementia compared with healthy controls and a 26% increased risk compared with those with treated hypertension. Compared to healthy controls, those with treated hypertension had no significantly increased dementia risk. There were no significant interactions with age, sex, or racial group.
The researchers are aware of the study’s limitations. One is that definitions of hypertension change over time and vary across locations, leading to potential differences in diagnosis. Similarly, the diagnosis of dementia was made using different methods. Also, the brief time to onset of dementia in some studies suggests the presence of baseline cognitive impairment. Nonetheless, they say their findings are important and should inform treatment decisions.
“Our study … provides the strongest data yet for the importance of antihypertensive use even in late life, and that more than a single late-life BP measure is needed to guide risk stratification and treatment decisions,” said the researchers.
The study was published in the journal JAMA Network Open.