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Can dementia be prevented? Will exercise or nutritional supplements improve cognitive decline? Prepare to be disappointed. This is Healthcare Triage News.

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Will exercise or nutritional supplements improve cognitive decline? Prepare to be disappointed. This is Healthcare Triage News.

First up, effective at 24 month physical activity intervention for health education on cognitive outcomes in sedentary older adults - the life randomized trial. 

We have lots of epidemiological evidence that physical activity is associated with better cognition but that could be reverse correlation. We need a randomized controlled trial, and this is it.

Researchers randomized more than 1600 elderly people who were sedentary to: 1 - A structured, moderate intensity physical activity program, including walking, resistance training, and flexibility exercises or 2: A control health education program of workshops and upper-extremity stretching.

They measured a number of cognitive outcomes, including the Digit Symbol Coding (or DSC) task subtest of the Wechsler Adult Intelligence Scale and the revised Hopkins Verbal Learning Test. They also measured global and executive cognitive function and dementia 2 years after the intervention.

At 2 years, the scores of the cognitive tests were no different between the groups. On a 133 point scale, the mean scores of the DSC were 46.26 in the physical activity group and 46.28 in the control group. The HVLT (which could score up to 12) was 7.22 in the physical activity group and 7.25 in the control group.

There were also no significant differences in the measures of global or executive cognitive function, nor any in the diagnoses of cognitive impairment or dementia.

The second study tried to different approach. Effect of Omega-3 fatty acids, lutein/zeaxanthin, to other nutrient supplementation on cognitive function. The AREDS2 Randomized Clinical Trial.

As with physical activity, there's lots of observational data linking diet with Alzheimer's disease, but no randomized controlled trials testing nutrients with cognitive changes. This is that RCT.

Using the infrastructure of another trial investigating macular degeneration in elderly people, researchers randomized more than 3700 participants for this trial.

They got long-chain polyunsaturated fatty acids, lutein, zeaxanthin and/or placebo in factorial design. They also got varying combinations of vitamins C, E, beta carotene and zinc.

Then, at baseline every 2 years they were assessed. The main outcome of interest was a composite score of a battery of cognitive function tests and the score could range from -22 all the way up to 17.

On that scale, the yearly change for those who received supplements was -0.19 for those who got long-chain polyunsaturated fatty acids and -0.18 for those who did not.

Needless to say, this was not a significant difference. Those who received lutein and zeaxanthin had a score change of -0.18 versus -0.19 in those who did not. Again, not significant. Supplementation with these nutrients had no effect on cognition.

The accompanying editorial offered some hope, because other studies have shown benefits to physical activity. And I'll quote from it.

"The FINGER trial reported results of a multifaceted intervention that included diet, exercise, cognitive training, and vascular risk monitoring compared with provision of general health advice in participants aged 60 to 77 years who were at risk of developing dementia.

"At 2 years, the intervention was associated with significant benefits on a comprehensive neurophysiological test battery"

And they're right! These studies should be added to others, not replace them. And I agree with this, too:

"It is likely the biggest gains in reducing the overall burden of dementia will be achieved through policy and public health initiatives promoting primary prevention of cognitive decline rather than efforts directed toward individuals who have already developed significant cognitive defects"

It does seem likely that incorporating physical activity and maybe even diet, into holistic changes earlier in life, are likely to do health and cognitive decline than waiting until problems have develops later in life.

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