Healthy Habits in Midlife May Ward Off Cognitive Decline

Fran Lowry

May 31, 2016

Being physically active, maintaining normal blood pressure, and having healthy levels of HDL cholesterol may help maintain later-life verbal memory skills, new findings from a longitudinal prospective study suggest.

"The beneficial influence of physical activity and blood pressure together approximately compensates the negative influence of age," the investigators, led by Cassandra Szoeke, MD, University of Melbourne, in Australia, write.

The study was published online May 18 in the American Journal of Geriatric Psychiatry.

Key Intervention Targets

It is well known that abnormalities in brain structure and function can occur several decades prior to the onset of cognitive decline. Therefore, the authors reason that "it is very likely that the preceding decades are the time when an intervention is likely to be most effect, when informed by an understanding of factors contributing to the disease prodrome."

Dr Cassandra Szoeke

But they point out that few studies have sufficient longitudinal data on "relevant risks to determine the optimum targets for interventions to improve cognition in ageing."

"There have been many studies looking at the influence of different factors on cognition and dementia," Dr Szoeke told Medscape Medical News.

"There has been conflict in the literature. For example, some studies show that high cholesterol is associated with developing dementia, some show there is no association, others show that low cholesterol is associated with dementia. Many of the risk factors studied in all these different papers are, in fact, interrelated. So we sought to study all the risks together, to determine which risk factors were associated with cognitive decline," Dr Szoeke added.

"The second reason is that we recently published [a study that showed] brain changes associated with dementia take 20 to 30 years to develop, so we know that the risk factors associated with dementia take decades to evolve pathology. To understand them, you need a study which is decades long, and there are not many of these. So we wanted to look across 20 years of risk exposures to examine the effect of the timing, including when these risk factors are important and for how long are they important," she said.

To examine the timing and exposure of factors contributing to verbal memory performance in later life, the investigators analyzed data from 387 participants aged 45 to 55 years from the population-based Women's Healthy Ageing Project who were identified by random population sampling in 2001.

The mean age at study entry was 49.6 years. At baseline, complete neuropsychiatric assessments were performed, and clinical information, sociodemographic information, physical measures, and biomarkers were collected. Participants presented for at least three follow-up visits, which included at least one cognitive reassessment.

The primary outcome measure used in the study was verbal episodic memory, which was assessed by a modified version of the assessment battery of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD).

"Studies have shown that the earliest change to cognition is in verbal episodic memory, and the CERAD is sensitive to early changes associated with dementia," Dr Szoeke said.

The findings showed that physical activity was the most important factor predictive of better verbal memory. For every mean day of physical activity, CERAD scores increased by a mean of 0.136 (.058, .214; P < .001).

HDL cholesterol level was the next most significant predictor of cognitive performance after physical activity.

Mean HDL levels measured from the time of early menopause years were associated with an increase in memory score by 0.818 (0.042, 1.593; P < .001) per mmol/L of HDL.

High systolic and high diastolic blood pressure both negatively affected verbal memory performance over time.

Mean arterial pressure (MAP) provided the best estimate of the overall effect of blood pressure; the mean MAP over all years since before menopause was associated with a mean decrease in CERAD score of 0.033 (-.047, -0.18; P < .001) per mmHg.

Age and education were also variables of cognition, she said.

Age was associated with a constantly decreasing value of the CERAD score of -0.122 (-149, -0.095; P < .001) per year. Higher educational level was associated with an improvement in the CERAD score by 0.38 (0.20, 0.55).

"Activity done even in the last 10 years of the study could still improve your cognition. However, we also caution that the best effect was cumulative, so not targeting risk factors for the first 10 years misses 10 years of potential benefit," Dr Szoeke said.

"Doctors should be telling their patients to do more physical activity, because it helps your heart, it helps your brain, it prevents obesity and diabetes, so move more, move often," she said.

Confirmatory Findings

Commenting on the findings for Medscape Medical News, Heather M. Snyder, PhD, senior director of medical and scientific operations at the Alzheimer's Association, Chicago, Illinois, said strengths of the study include the population and the long-term follow-up.

"It's a large number of women who have been followed over a long period of time. It adds to our information, and it supports findings from other studies that we've seen, so it's confirmatory and adds to what we know and supports the findings from other studies in an independent population," Dr Snyder said.

"Alzheimer's is incredibly complex. There are things that come into play that we don't completely understand, for instance, genetics, environment, and how they might work together. That's why studies like this one, where you have a population of women who are being followed for a long period of time, are helpful in starting to tease out some of those lifestyle factors that may be more important at different time points in your life" she said.

"Even among individuals experiencing memory changes, being physically active is still beneficial. There's a higher quality of life and less agitation for those individuals," Dr Snyder added.

The study was funded by the National Health and Medical Research Council and the Alzheimer's Association. Dr Szoeke reports no relevant financial relationships. Dr. Snyder is an employee of the Alzheimer's Association but did not take part in the study.

Am J Geriatr Psychiatry. Published online May 18, 2016. Abstract


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