Feb 18 2022

Exercise For Your Memory

Most people I know, whether personally or as my patients, want to take positive steps to improve their health and quality of life. Unfortunately, many people who make a decision to get healthier rely on information in the popular culture and being promoted by the self-help industry. Much of this information is wrong or misleading. When people want to improve their diet, they often tell me they only eat organic whole foods, or perhaps they go paleo or raw if they are really motivated. But these changes are worthless – just expensive distractions.

Older patients concerned about their memory and cognitive function tend to focus on two things, diet and “brain games”. As I have discussed before, brain games basically don’t work. If you play Wordle, you get better at Wordle. That’s it. Diet is a little more complicated, as some people, especially older adults, may be deficient in certain nutrients, particularly B12. Even here people get distracted by the notion of “super foods” or some magical supplement. The reality is, for most people, just have a good well-rounded diet and eat plenty of fruits and vegetables. Vitamin B12, however, largely comes from meat. It is also a difficult vitamin to absorb (it requires a cofactor) and some people have impaired absorption or it wanes as they get older. The solution here is to get regular checkups with your PMD, who will check your B12 level and supplement if necessary. You may even need a B12 shot if your GI absorption is really impaired.

But we haven’t even discussed the factors that have perhaps the greatest effect on the cognitive function of healthy adults. I emphasize healthy, because if someone has a disease that affects their brain function that is a separate issue. Perhaps the most significant single factor affecting memory is healthy adults is sleep. Often sleep gets difficult as we get older for various reasons. People become accustomed to chronically poor sleep, and underestimate its affect on their cognitive function and memory. So step one should always be – fix your sleep. You may be able to do this with improved sleep hygiene, but if this doesn’t fix the problem again you need to see your doctor. You may have a sleep disorder, such as sleep apnea (difficulty breathing when asleep), and this will wreak havoc on your memory. Some people also struggle with anxiety and depression, and this can impair memory and focus. So address those issues as well.

An often neglected factor, something positive that older adults (and everyone) can do to support their brain function, is physical exercise. This is an easy recommendation to make, because this is something everyone should be doing anyway. It’s not exactly clear why exercise improves brain function, but there are some plausible hypotheses. It may be more that inactivity impairs brain function, it may be due to overall improved physiological function or cardiopulmonary health. Also, you don’t need athletic training, 30 minutes of moderate exercise three days a week is enough to see a benefit.

But while the research does seem to show a benefit from exercise, the results of clinical trials have been mixed and a statistical benefit has been difficult to nail down. A recent systematic review and meta-analysis sought to settle the issue, and (cutting to the chase) they found a statistical benefit to episodic memory function for adults 55-68 years old from moderate exercise. But let’s unpack this a bit.

The researchers found 36 studies meeting inclusion criteria with a total of 2,750 subjects. They then pooled the data, which was challenging because they had to combine data from trials with different details (in terms of interventions, populations, and outcome measures). In the end they found that the pooled data showed a statistical benefit from episodic memory, which is memory of past events in your life. The benefit was clear for those 55-68, but not statistically significant for those 69-85.

This is a good use for a meta-analysis – combining data from many studies to increase the power of the data (the ability to detect smaller signals). But doing a meta-analysis introduces new potential biases. How were the trials chosen, how was the data combined? Also, when the outcome is positive only for a subgroup, each caveat makes me a bit queasy. Were other variables looked at and not found to be significant? Was this just all p-hacking and cherry picking? Did the researchers expect this subgroup to be significant before they started parsing the data?

For me the outcome here is plausible, does align with the best studies, and there is reason to predict these variables were the ones that mattered. But still, I would like to see a large trial to confirm these findings. A meta-analysis is useful, but not as predictive as a single rigorous and large trial.

In the meantime, what should we do with these results? Given that the resulting recommendation is for regular moderate exercise, something which we already know is beneficial in other ways, there isn’t much controversy. I would say – engage in regular moderate exercise, it’s good for your cardiovascular health, its good for your muscle and bone health, and it may be beneficial for your cognitive function. There is also a suggestion that you should start this behavior early. If you wait too long, the benefits are likely to wane and may disappear.

And once again we come back to the basic recommendations for overall health – sleep well, have a healthful varied diet, get regular exercise, and avoid smoking and excess alcohol. When people want to get healthy, they should focus on these things. These are the “95% answer”. Everything else is nibbling around the edges, and may even be worthless. There is no secret hack, no “crazy trick”, and no magic pill or superfood.



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