We have written before avoiding Alzheimer’s in many different ways, for example:

Alzheimer’s Causative Factors To Avoid

…and regular readers will also be aware of our dictum “what’s good for the heart, is good for the brain”, which is because the heart feeds the brain, with oxygen and nutrients, and also ultimately clears away detritus like beta-amyloid (associated with Alzheimer’s).

For much more detail on this, see: What’s Your Vascular Dementia Risk? ← includes actual numbers and a risk calculator tool and things like that

So, it’s no surprise of course that exercise is protective against dementia, and as per the above, typically the most important thing here is heart health, so getting regular cardiovascular exercise, such walking, running, or dancing is great. Cycling too. Things like that.

Beyond cardio

First, some background. A previous (2023) study concluded:

❝Among older adults, more time spent in sedentary behaviors was significantly associated with higher incidence of all-cause dementia. Future research is needed to determine whether the association between sedentary behavior and risk of dementia is causal.❞

Source: Sedentary Behavior and Incident Dementia Among Older Adults

We’re not going to go deeply into that paper, because our interest today is about the answer to that call of “future research is needed”, because a team of scientists have now delivered on that.

In terms of how recent this new research is, it was published today (at time of writing), in the Journal of the Alzheimer’s Association.

In it, Dr. Marissa Gogniat et al. examined the relationship between sedentary behavior and cognitive decline and neurodegeneration, in 404 adults aged 50+.

A note on “cognitive decline” and “neurodegeneration”: those two terms are often used interchangeably, because they are usually strongly associated with each other so if one goes up or down then so does the other, but technically:

• cognitive decline = a decline of cognitive abilities, as measured by cognitive performance tests
• neurodegeneration = physical degeneration of neural tissue, typically specifically in the brain, as measured by various physical markers of neurodegeneration (tests range from brain scans to blood markers to biopsies and more, but the point is that it’s all physical stuff)

While based on the one-line summary we gave (“examined the relationship between sedentary behavior and cognitive decline / neurodegeneration”), this can sound a bit like a “examined whether water is wet” study, but in fact it becomes interesting when physical exercise is controlled for, since they found:

❝Reducing your risk for Alzheimer’s disease is not just about working out once a day. Minimizing the time spent sitting, even if you do exercise daily, reduces the likelihood of developing Alzheimer’s disease.❞

~ Dr. Marissa Gogniat

Too vague? Here’s the less vague version:

❝In cross-sectional models, greater sedentary time related to a smaller AD-neuroimaging signature (β = -0.0001, p = 0.01) and worse episodic memory (β = -0.001, p = 0.003). Associations differed by APOE-ε4 status. In longitudinal models, greater sedentary time related to faster hippocampal volume reductions (β = -0.1, p = 0.008) and declines in naming (β = -0.001, p = 0.03) and processing speed (β = -0.003, p = 0.02; β = 0.01, p = 0.01).❞

In other words:

• Those are very significant findings, statistically speaking; the causal association cannot be reasonably denied without some strong new evidence for why
• Greater sedentary behavior is related to neurodegeneration and worse cognition.
• Sedentary behavior is an independent* risk factor for Alzheimer’s disease.
• Associations differed by APOE-ε4 carrier status in cross-sectional models.

*as in, the sedentary risk factor stands (so to speak) regardless of whether you exercise a lot

With regard to “Associations differed by APOE-ε4 carrier status in cross-sectional models.”, that’s a little complicated, as …

❝Interestingly, we only found a sedentary time x APOE-ε4 status interaction on occipital volume longitudinally (which did not survive correction for multiple comparisons) and no interactions on cognition. The significant effect on occipital lobe volume was driven by APOE-ε4 non-carriers, which does not align with our cross-sectional findings. APOE-ε4 carriers are thought to have accelerated gray matter volume loss, starting possibly in middle age. Therefore, while increased sedentary time may impact gray matter volume among APOE-ε4 carriers, this effect may be masked by the cumulative effect of APOE-ε4 on brain volume over the lifespan that is captured at baseline.❞

In other words: in all likelihood, having the APOE-ε4 mutation probably means it’s extra important for you to not be sedentary in your lifestyle, and (good news) being non-sedentary is probably disproportionately impactful for you in a positive way, but (bad news) the APOE-ε4 mutation causes such an increased risk already, that it’s difficult to 100% ascertain that statistically, without larger samples starting earlier in life.

You can read the paper in full here:

Increased sedentary behavior is associated with neurodegeneration and worse cognition in older adults over a 7-year period despite high levels of physical activity

“What if have to spend a lot of time sitting down?”

A valid question, relevant for many.

For this, check out:

Stand Up For Your Health (Or Don’t) ← our main feature on this also includes more things you can do if you must sit, to make sitting less bad!

Take care!