Walkolution Blog

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Researchers link sedentary lifestyle with structural changes in the memory center

Sep 23, 2019 2:00:00 PM

Research in recent years has clearly shown that sitting is associated with a large number of actually preventable chronic diseases. The common basis of many of these diseases is the inability of the body to metabolize sugar and fats effectively during long periods of sitting.

This leads to overweight and diabetes, among other things, but also to chronic subliminal inflammatory processes (low-grade inflammations), which in turn seem to be the cause of diseases of the blood vessels (increased risk for heart attack, stroke, kidney diseases). Many people think primarily of back pain with regard to the problems of sitting too much. However, it becomes clear, that those who sit a lot also damage their mental health. In addition to depression, increased susceptibility to burnout and stress reactions, the influence on memory performance is currently in the spotlight of research. This is an urgent issue because dementia represents a significant burden on our health systems and the rate of new cases is rising rapidly. Statistically, the diagnosis of dementia is made every 3 seconds. By 2050, the number of Alzheimer’s patients is expected to increase from the current 46.8 million to over 130 million. (Dementia statistics | Alzheimer’s Disease International)

Sitting shrinks the hard disk of the brain

A new study from the Semel Institute for Neuroscience and Human Behaviour at the University of UCLA shows for the first time that people who sit more also show structural changes in the brain in the area of the so-called medial temporal lobe (MTL). This area is responsible for our memory performance.

 
 

© 2018 Siddarth et al. Oblique coronal images are acquired to cover the long axis of the hippocampus as shown in image A. This image is cropped over the area of interest (red square) and shown in greater detail in image B. The gray matter ribbon (shown in bright blue) is segmented out from the surrounding MTL area. C. Boundaries between subregions are demarcated on each slice and projected to the corresponding location in flat-map space (shown in E). Boundaries between these subregions are shown in C and projected to flat-map (or 2D) space as shown in Fig E. D. Thickness in gray matter space is calculated in-plane space by taking the maximum distance value of the corresponding 3D voxels across all layers and multiplying by two to arrive at a thickness value for each voxel. E. The subregions are labeled as follows: cornu ammonis (CA) fields 1, 2, 3 and the dentate gyrus (DG) subiculum (Sub), entorhinal cortex (ERC), perirhinal cortex (PRC), parahippocampal cortex (PHC) and fusiform cortex (Fus). Boundary colors in C correspond to the same color scale in E and are labeled according to the Boundary Demarcation color bar.

 

The study examined a total of 35 persons (25 women and 10 men, aged 45–75). Magnetic resonance imaging (MRI) was performed on all individuals and their sitting behavior was assessed using a standardized questionnaire.

The more time the subjects spent sitting, the thinner the thickness of the medial temporal lobe was. The more active the participants were on the other side, the more structured the respective area was in the MRT.

Similar changes in this area of the brain are also regularly found in patients with dementia. The author of the study, Prabha Siddarth, explains the relevance of the study: “The finding that sitting reduces the anatomy of these important brain structures is extremely relevant because it also suggests that reducing sedentary behavior might be a possible intervention to improve mental performance in patients with memory disorders”.

Exercise fails to protect

Interestingly, the study also shows that participants who did regular sports but still spent 8 or more hours per day sitting had the same changes. “Exercise is good and certainly indispensable for optimal mental performance, but a sedentary lifestyle is an independent risk factor,” say the authors of the study.


Walking training for patients with advanced dementia

Dementia that has already occurred with impairment of independence in everyday life does not seem to be reversible in most cases. For many of those affected, however, a slight improvement already represents a significant gain in everyday life.

A Dutch research group, which published its results in the Journal of Aging, was also able to show that light aerobic activity such as walking can be a suitable measure to achieve cognitive improvement in everyday life in patients with advanced dementia.

The researchers divided a total of 122 participants into two performance groups and let them complete two one-hour accompanied walking training per week. Depending on their performance, the test persons who were residents of an old-age facility were divided into two different levels. After one year, both groups showed significant improvements in their memory performance and scored significantly better in tests that recorded their everyday coping.

What is the mechanism behind this?

What is the link between inactivity, shrinkage of the mediotemporal lobe (MTL) and the development of dementia?

BDNF (Brain Derived Neurotrophic Factor), often referred to as the “brain fertilizer”, plays a central role in this process thanks to the ability of BDNF to facilitate and support the growth of neuronal stem cells (neuroplasticity and neurogenesis). In brain autopsies of Alzheimer patients, significantly reduced BDNF microRNA levels could be detected in the mediotemporal lobe (a 3.4-fold decrease compared to control groups). Everyday exercise and training promote the release of BDNF. The body seems to be preparing the brain for the increased demands that come along with complex movements. Just as a muscle grows through a training stimulus, the brain is also stimulated in its growth. A mechanism that has made us what we are today in our millions of years of development.

Movement — especially in old age!

One problem is that the causal processes reinforce each other. Patients suffering from dementia also restrict themselves physically further, which in turn promotes the progression of dementia. Movement, especially in the form of walking, is, therefore, one of the best and safest means to become active preventively and therapeutically. If at any time you should find yourself in the situation of choosing an elderly home for your parents, please do not judge it by how good the recliners are with a view from the window, but rather how exercise and walking are integrated into everyday life. The more the better, even in old age!

 

Eric Söhngen, M.D., Ph.D.
Written by Eric Söhngen, M.D., Ph.D.

Eric is a board-certified physician and holds a doctorate in neuronal stem cell physiology from the Technical University of Munich (TUM). He is the author of the bestselling book Death by Sitting - why we need a movement revolution.

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