Can exercising when you’re a teen prevent young onset dementia?

CurioCity writer
15 September 2015

Above: Image © wildpixel, iStockphoto.com

Alzheimer’s disease (AD) probably makes you think of the elderly. After all, the majority of people living with the disease are over the age of 65. However, there is also a form of the disease that causes young onset dementia (YOD). In these cases, symptoms normally start to appear when people are in their 40s or 50s. What's more, research suggests that changes in the brain that eventually cause dementia may begin up to 20 years before any symptoms appear. Although there are medications that can reduce some symptoms like memory loss, there is currently no cure for dementia caused by AD.

Did you know? By 2030, there will be 75 million  people living with dementia worldwide. This number is projected to skyrocket to 135.5 million by 2050!AD develops very gradually by destroying neurons (brain cells). The idea that this damage can start years before a person experiences memory loss or language problems has led scientists to study risk factors in much younger people. They have even begun looking at how teen lifestyles affect the chances of developing dementia later in life. For example, you may know that exercising regularly can reduce stress, improve your mood, and do other great things for your health. But exercising more when you’re young could also reduce your chances of developing YOD.

A few studies have found a link between an active lifestyle when you’re young and reduced rates of cognitive decline later in life. Cognitive decline is the normal process that gradually makes it harder to remember things and learn new ones as a person gets older.

For example, a team of Swedish researchers studied the exercise levels and cognitive performance of more than a million men. Data collected when the study participants were 18 were compared to tests performed up to 42 years later. The researchers found that men who exercised less in their teens had a higher risk for developing YOD later in life.

Did you know? A key feature of Alzheimer’s disease is the buildup of toxic proteins in the brain called tau and beta amyloid.Another study assessed exercise levels of female participants of different ages by using  a questionnaire. It found that participants who reported a physically active lifestyle at any age, but especially as a teen, had a lower risk for developing dementia.They also had a lower risk for more mild forms of cognitive impairment, such as trouble concentrating or making decisions.

So what happens in your brain when you exercise that might help prevent dementia later on? Let’s find out! When you exercise, your brain experiences higher levels of neurotrophic factors. These are a family of proteins that help neurons survive and grow. Two examples of neurotrophic factors are brain-derived neurotrophic factor (BDNF) and insulin like growth factor 1 (IGF-1). When they are released in your brain, both BDNF and IGF-1 help improve your memory, ability to learn, and neuroplasticity.

Neuroplasticity is your brain's ability to adapt to changes in your environment. That includes finding ways of compensating for an injury or the effects of disease by forming new connections between neurons. So when one part of the brain is damaged, neuroplasticity allows for the affected neurons to form new connections. As a result, some of the functions in that particular area can be restored. Did you know? For a person to be diagnosed with dementia, they must have cognitive impairment that prevents them from performing daily tasks, as well as severely impaired memory.

Location of the Broca area in the left hemisphere of the brain. Click image to enlarge (DBCLS, Wikimedia Commons)

For example, imagine you injured the Broca area in the left hemisphere (side) of your brain. That’s the part of the brain that controls your ability to understand language and speech. Does this mean that you will never be able to speak or hold a conversation again? Not necessarily. Over time, the undamaged right hemisphere of your brain may be able to take over some of the left hemisphere’s functions as new connections between neurons are formed. 

Scientists also think that by improving neuroplasticity when you’re a teen, exercise may help your brain build up resistance to cognitive decline. This would protect your brain against dementia, including YOD, or at least slow its development.

This all sounds great! But since only a few studies have looked at risk factors for YOD in teens, more research is needed to confirm the results. In particular, there are weaknesses in some of the existing studies that researchers need to address in future ones. For example, the female participants in the study mentioned above self-reported their level of exercise instead of being directly assessed by researchers. Direct assessment likely would have provided less subjective and more reliable data that could be reproduced in future studies.

But regardless of what scientists find out in future studies, they’re already sure of one thing: exercise is good for you. So it never hurts to get up and get active!


Learn more!

Articles and websites with general information on Alzheimer’s disease and dementia:

Dementia Fact Sheet (2015)
World Health Organization

Seeking a cure for Alzheimer’s disease (2015)
Sakino Bano Mendha, CurioCity by Let’s Talk Science

What causes Alzheimer's disease? (2010)
CurioCity by Let’s Talk Science

About dementia
Alzheimer’s Society of Canada

Alzheimer’s Disease
US Alzheimer’s Association

Alzheimer’s Disease Education and Referral Center
US National Institute on Aging

Articles on the effects of exercise on the brain, including scientific articles on the role of growth factors and increases in neuroplasticity:

Multitasking molecules: Healthy body, healthy brain (2013)
Anna Zhou, CurioCity by Let’s Talk Science

Physical exercise as a preventive or disease-modifying treatment of dementia and brain aging (2011)
J. E. Ahlskog, Y. E. Geda, N. R. Graff-Radford & R.C. Petersen, Mayo Clinic Proceedings 86

Exercise builds brain health: key roles of growth factor cascades and inflammation (2007)
C. W. Cotman, N. C. Berchtold & L. A. Christie, Trends in Neurosciences 30
Link to abstract. Registration or subscription required to view full text.

Hippocampal BDNF mediates the efficacy of exercise on synaptic plasticity and cognition (2004)
S. Vaynman, Z. Ying & F. Gomez-Pinilla, European Journal of Neuroscience 20
Link to abstract. Registration or subscription required to view full text.

Scientific articles on the effects of exercise on rates of dementia later in life:

Cardiovascular and cognitive fitness at age 18 and risk of early-onset dementia (2014)
Jenny Nyberg et al., Brain: A journal of neurology
Risk factors in late adolescence for young-onset dementia in men: a nationwide cohort study (2013)
P. Nordstrom, A. Nordstrom, M. Eriksson, L. O. Wahlund & Y. Gustafson, JAMA Internal Medicine 173

Physical Activity Over the Life Course and its Association with Cognitive Performance and Impairment in Old Age (2010)
L. E Middleton, D. E Barnes, L.-Y. Lui & K. Yaffe, Journal of the American Geriatric Society 58
Link to abstract. Registration or subscription required to view full text.

Early life physical activity and cognition at old age (2003)
M. Dik, D. J. Deeg, M. Visser, C. Jonker, Journal of Clinical and Experimental Neuropsychology 25

Does active leisure protect cognition? Evidence from a national birth cohort (2003)
M. Richards, R. Hardy & M. E. Wadsworth, Social Science & Medicine 56
Link to abstract. Registration or subscription required to view full text.

Websites with general information on neuroplasticity:

The brain's amazing potential for recovery (2011)
Elizabeth Laudau, CNN

Neurobiology: Neuroplasticity (2010)
Stephanie Liou, Huntington’s Outreach Project for Education, Stanford University

CurioCity writer

Article written by a CurioCity expert.


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