Biggest risk factors identified to try and prevent Alzheimer's disease

Clinicians should identify and target 10 risk factors in their attempt to prevent Alzheimer's disease, say researchers

July 20, 2020

Science Daily/BMJ

There are at least 10 risk factors that appear to have a significant impact on a person's likelihood of developing Alzheimer's disease that could be targeted with preventative steps, suggests research published in the Journal of Neurology, Neurosurgery & Psychiatry.

Focusing on these factors, which include cognitive activity, high body mass index in late life, depression, diabetes, and high blood pressure, could provide clinicians with an evidence based guideline for prevention of Alzheimer's disease, but a lot more research is needed to come up with other promising approaches to preventing the condition.

Currently, around 850,000 people in the UK are affected by dementia -- around two thirds of which are Alzheimer's disease -- and the condition is a leading cause of death, not helped by the fact that there have been no new drug treatments for dementia in almost 20 years.

Experts are predicting rising case numbers as the population ages but recent research has suggested that the number of cases appears to be reducing, possibly due to lifestyle changes, better education and risk reduction strategies to prevent or delay dementia.

Existing evidence on preventing Alzheimer's disease is challenging to interpret due to varying study designs with different endpoints and credibility.

So an international team of researchers led by Professor Jin-Tai Yu at Fudan University in China, set out to review and analyse current evidence in order to produce evidence-based suggestions on Alzheimer's disease prevention.

The researchers gathered 395 studies (243 observational prospective studies and 152 randomised controlled trials) that were suitable for their analysis.

From analysing these, they proposed 21 suggestions based on the consolidated evidence available that could be used in practice by clinicians to try to prevent Alzheimer's disease.

Within these, there were what they referred to as "Class I" suggestions to target 19 different factors.

Nearly two-thirds of these suggestions would involve targeting vascular risk factors (such as high blood pressure and cholesterol levels) and lifestyle, strengthening the importance of keeping healthy to prevent Alzheimer's disease.

Ten of the suggestions were backed by strong evidence and included receiving as much education as possible in early life, participating in mentally stimulating activities such as reading, avoiding diabetes, stress, depression, head trauma, and high blood pressure in midlife.

A further nine suggestions had slightly weaker evidence to support them and included regular physical exercise, getting sufficient good quality sleep, maintaining a healthy body weight and good heart health in later life, avoiding smoking, and including vitamin C in the diet.

In contrast, two interventions were not recommended -- oestrogen replacement therapy and use of acetylcholinesterase inhibitors (drugs that increase communication between nerve cells).

The authors point to some study limitations, such as the fact that observational studies cannot indicate a clear causal relationship and randomised controlled trials cannot be generalisable beyond the specific sample, intervention, dose and duration studied.

In addition, the values of their suggestions might be limited by geographic variability, definition of exposure and prevalence of risk factors at population level.

Nevertheless, the authors say this was the most comprehensive and large-scale systematic review and meta-analysis for Alzheimer's disease to date, and the evidence based suggestions were put together by integrating a large amount of evidence from different types of existing research.

They conclude: "This study provides an advanced and contemporary survey of the evidence, suggesting that more high-quality observational prospective studies and randomised controlled trials are urgently needed to strengthen the evidence base for uncovering more promising approaches to preventing Alzheimer's disease."

https://www.sciencedaily.com/releases/2020/07/200720190920.htm

High blood pressure treatment may slow cognitive decline

September 5, 2019

Science Daily/American Heart Association

Among middle-aged and older adults, high blood pressure accelerated cognitive decline and treatment slowed the regression. The rate of cognitive decline was similar between adults receiving high blood pressure treatment and those who did not have high blood pressure at all.

High blood pressure appears to accelerate cognitive decline among middle-aged and older adults and treating high blood pressure may slow down the process, according to a preliminary research presented at the American Heart Association's Hypertension 2019 Scientific Sessions.

The findings are important because high blood pressure and cognitive decline are two of the most common conditions associated with aging, and more people are living longer worldwide.

According to the American Heart Association's 2017 Hypertension Guidelines, high blood pressure is a global health threat, affecting approximately 80 million U.S. adults and one billion people globally. Moreover, the relationship between brain health and high blood pressure is a growing interest as researchers examine how elevated blood pressure affects the brain's blood vessels, which in turn, may impact memory, language and thinking skills.

In this observational study, researchers from Columbia University analyzed data collected on nearly 11,000 adults from the China Health and Retirement Longitudinal Study (CHARLS) between 2011-2015, to assess how high blood pressure and its treatment may influence cognitive decline. High blood pressure was defined as having a systolic blood pressure of 140 mmHg or higher and a diastolic blood pressure of 90 mmHg or higher, and/or taking antihypertensive medications. (Note: The American Heart Association guidelines define high blood pressure as 130 mmHg or higher or a diastolic reading of 80 mmHg or higher.)

Researchers in China interviewed study participants at home about their high blood pressure treatment, education level and noted if they lived in a rural or urban environment. They were also asked to perform cognitive tests, such as immediately recalling words as part of a memory quiz.

Among the study's findings:

Overall cognition scores declined over the four-year study;

Participants ages 55 and older who had high blood pressure showed a more rapid rate of cognitive decline compared with participants who were being treated for high blood pressure and those who did not have high blood pressure; and

The rate of cognitive decline was similar between those receiving high blood pressure treatment and those who did not have high blood pressure.

The study did not evaluate why or how high blood pressure treatments may have contributed to slower cognitive decline or if some treatments were more effective than others.

"We think efforts should be made to expand high blood pressure screenings, especially for at-risk populations, because so many people are not aware that they have high blood pressure that should be treated," said presenting study author Shumin Rui, a biostatistician at the Mailman School of Public Health, Columbia University in New York. "This study focused on middle-aged and older adults in China, however, we believe our results could apply to populations elsewhere as well. We need to better understand how high blood pressure treatments may protect against cognitive decline and look at how high blood pressure and cognitive decline are occurring together."