The simple habit of getting in a daily walk has been shown to have numerous health benefits over the last few years. In a remarkable study, scientists found that taking just 5,000 steps a day can help slow Alzheimer’s disease-related decline. Sounds like an easy win, no?
Walking 5,000 steps translates to approximately 2 to 2.5 miles (or about 3.2 to 4 km) for an average adult – and that can take about 35 minutes at a moderate pace. That's pretty doable – and you can also cover a lot of that by simply being active in and around the house.
Before we get into the newly published research that just appeared in Nature Medicine, here's a quick primer on Alzheimer's disease. The condition is caused in part by Amyloid-beta protein clumps forming outside of neurons as plaques, which can lead to the malfunctioning of tau proteins. That, along with a host of other factors, impedes normal brain activity and causes symptoms that can progress from forgetfulness to delusions to difficulty eating, moving around, and speaking.
The novel study was conducted over the course of 14 years, and involved nearly 300 cognitively unimpaired adults aged 50-90 years. They were enrolled in the Harvard Aging Brain Study, and participated in pedometer-measured physical activity, longitudinal amyloid and tau PET imaging, and annual cognitive assessments throughout this period.
The researchers, who are based in Australia, Canada and the US, found that higher physical activity was linked to slower amyloid-related cognitive decline. This in turn was associated with the slowing of toxic tau accumulation in the brain, especially in people who already displayed initial signs of Alzheimer's.
That buildup is typically seen as a key indicator of the disease worsening. As such, slowing this down amounts to delaying a person's decline in thinking and memory skills.
Interestingly, tau accumulation and cognition plateaued at a sweet spot of 5,000–7,500 steps per day. So while walking more than that might benefit other aspects of your life, the effect of staving off Alzheimer's may not scale proportionally beyond this level. However, it's worth noting that for sedentary people, getting in even 3,000-5,000 steps a day was linked to significantly lower tau accumulation than restricting activity to fewer daily steps.
How is this happening? Physical activity is thought to help the brain stay resilient by boosting the systems that keep it fed and clean. Exercise is linked to greater cerebral blood flow in cognitively unimpaired older adults. Poor blood flow is often impaired early in the Alzheimer’s disease process, so physical activity might directly counteract this problem.
Similarly, moving more leads to better heart and lung fitness. This improved fitness has been shown to potentially dampen the negative influence that the Amyloid-beta (Aβ) protein has on thinking skills. Beneficial Brain Chemicals (Molecular Pathways) Exercise may also change the chemical environment inside the brain, making it less hospitable to disease by decreasing inflammation (which is believed to play a role in promoting tau pathology).
That's pretty great for a preventive measure that doesn't involve medication or surgery, and can be incorporated into people's routines relatively easily. It also doesn't cost you anything.
With that, walking adds another feather to its cap of health benefits. In just the last couple of years, we've seen how just 4,000 steps a day can reduce your risk of dying by several percentage points, with no upper limit on the benefit. Just 25 minutes of walking each day instead of bed rest can help older people avoid getting weaker. Walking has also been found to reduce pain from arthritic knees, and strolls out in nature have been linked to reduced stress.
Get your fitness tracker on, get out there and touch some grass, folks.
Sources: University of Melbourne, Mass General Brigham via Scimex
