The surprising link between blood pressure and dementia

Key points:

• In a study of individuals older than 60 those with treated hypertension had a 26 percent lower risk of dementia compared to those with untreated hypertension

• The risk was substantially reduced in the treated hypertension group in those older than 65, 75 and 85

• Continuing antihypertensives in later life for those with a history of hypertension may substantially reduce dementia risk

New research found that people over the age of 60 who were treated for their high blood pressure had a 26 percent risk reduction for dementia when compared to those who were untreated.

The UNSW Sydney’s Centre for Healthy Brain Ageing published the recent findings in JAMA Network Open, highlighting that dementia risk was substantially reduced in the treated hypertension group throughout later life.

The study, which is the largest of its kind, looked at 34,519 people across 15 different countries, including Australia, USA, Brazil, China, Italy, Central African Republic and Nigeria.

Dementia may pose a burgeoning worldwide challenge, as approximately 57 million people currently live with dementia and an anticipated 153 million will have the condition by 2050. Hypertension is the most prevalent risk factor for dementia, affecting more than one billion people worldwide.

Despite the global risk, Australian researchers estimated that research on dementia outcomes would often lag behind in delivering tangible outcomes for people with the condition. 

Dr Matt Lennon, a medical doctor and lead author of the hypertension and dementia study, said the findings were critical for general practitioners and family physicians, who are most commonly at the forefront of blood pressure management.

“We know that mid-life hypertension increases [the] risk of all types of dementia by around 60 percent, and Alzheimer’s disease by 25 percent,” Dr Lennon explained.

“However, in late-life [ie. those over the age of 60] studies have variously found high blood pressure to increase, not affect or decrease dementia risk. This lack of clarity is deeply problematic.”

Dr Lennon revealed that the international research team clarified ambiguities in the field using the power of big data from CHeBA’s COSMIC — Cohort Studies of Memory in an International Consortium — collaboration.

The research also aimed to understand how age, sex and race might change the association between blood pressure, antihypertensive use and dementia. Dr Lennon said the research findings may influence the future of blood pressure management and future academic progress.

“This study provides responses to critical questions for public health,” Dr Lennon said.

The study had three big takeaways which were notably significant for the trajectory of dementia treatment:

1. Researchers found there were no significant differences in the effect of blood pressure or antihypertensive use in different sexes or racial groups
   
2. The study illustrated that a single measure of blood pressure in later life was not associated with significant differences in dementia risk and the authors suggested that multiple measurements over time should be used to direct treatment

3. People with unmedicated hypertension were found to have an elevated risk of dementia compared to those with medicated hypertension and healthy individuals — regardless of age

“This is a very promising result as it suggests that optimal care for one group will be similar for others,” Dr Lennon continued.

“No study previously has been able to assess the differential effects of blood pressure and antihypertensives in developing nations.

“Our study included three major studies of ageing based in Nigeria and the Central African Republic. It is critical that an understanding of chronic illness management in the developing world is published and disseminated. It is precisely in these areas where chronic illnesses are least well understood, but also where the majority of new dementia cases will occur in the coming decades.”

Professor Perminder Sachdev, co-director of CHeBA and co-author on the research, said “the findings indicate that ongoing antihypertensive therapy throughout late life is an important part of dementia prevention.”

When was the last time you had a blood pressure test? Do you live with hypertension? The team at Talking Aged Care are gearing up for Dementia Action Week — September 18 – 24, 2023 — so, sign up to the newsletter and stay up to date!