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Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study

BMJ 2017; 357 doi: https://doi.org/10.1136/bmj.j2709 (Published 22 June 2017) Cite this as: BMJ 2017;357:j2709

Effects of Physical Activity in Dementia: Is it Neuroprotective ?

Dementia is a serious mental illness, in which characterized by gradual progressive impairment of cognitive function (i.e brain functions) like perception, language, visuospatial orientation, decision making and most importantly motor skills, as a consequence, interfering with daily functioning and independent living.(1)

Statistically, an estimated 46.8 million people worldwide living with dementia in 2015 and this number is believed to be close to 50 million people at the end of this year 2017, Furthermore, it is expected to reach 75 million in 2030. With rough estimates that every 3 seconds someone in the world will develops dementia.(2)

Beyond question, exercise has a cascade of positive health benefits, including brain’s structure and health.(3)(4)(5)(6) Researches suggested that consistent aerobic exercise like daily 30 minutes promotes cognitive functions, healthy forms of neuroplasticity, in addition to healthy alterations in gene expression in the brain. Long-term effects of exercise include: increased neuron growth and neurological activity such as c-Fos signaling, over and above that, improvements in structural and functional brain structures and pathways associated with cognitive control and memory.(7)(8)(9) Risk factors of dementia is well known, and preventing or controlling these factors shall improve the outcomes of dementia, and thats by reducing the risk of cardiovascular disease, type 2 diabetes, obesity, hypertension, stroke, and dyslipidemia.

Sabia and colleagues(10) have a different point of view regarding the effect of physical activity in dementia, after they performed a prospective cohort study with a mean follow-up of 27 years, during in which they followed 10,308 patients and examined who developed incident dementia. Hence, authors conclude that there is no evidence of a neuroprotective effect of physical activity. However, they noted declining in physical activity levels began nine years before the diagnosis in people with dementia, and they stated that these findings attributed to the preclinical phase of dementia!

In my humble opinion, the conclusion i’ve come to in regard of physical activity and dementia is that it’s clearly that compliance to physical activity is having direct and indirect positive impact in dementia. Yet, we should close the gap between measuring a physical activity and reporting them in our researches, a proper methodological design should be looked at.

References:
(1) Activities of daily living in dementia: revalidation of the E-ADL test and suggestions for further development; Katharina Luttenberger, Anke Schmiedeberg, Elmar Gräßel BMC Psychiatry. 2012; 12: 208.
(2) M. Prince, A. Comas-Herrera, M. Knapp, M. Guerchet, and M. Karagiannidou, World Alzheimer Report 2016: Improving healthcare for people living with dementia: coverage, qualIty and costs now and In the future. Alzheimer's Disease International (ADL), London, UK, 2016.
(3) Erickson KI, Hillman CH, Kramer AF (August 2015). "Physical activity, brain, and cognition". Current Opinion in Behavioral Sciences. 4: 27–32. doi:10.1016/j.cobeha.2015.01.005.
(4) Paillard T, Rolland Y, de Souto Barreto P (July 2015). "Protective Effects of Physical Exercise in Alzheimer's Disease and Parkinson's Disease: A Narrative Review". J Clin Neurol. 11 (3): 212–219. PMC 4507374 Freely accessible. PMID 26174783. doi:10.3988/jcn.2015.11.3.212.
(5) McKee AC, Daneshvar DH, Alvarez VE, Stein TD (January 2014). "The neuropathology of sport". Acta Neuropathol. 127 (1): 29–51. PMC 4255282 Freely accessible. PMID 24366527. doi:10.1007/s00401-013-1230-6.
(6) Denham J, Marques FZ, O'Brien BJ, Charchar FJ (February 2014). "Exercise: putting action into our epigenome". Sports Med. 44 (2): 189–209. PMID 24163284. doi:10.1007/s40279-013-0114-1.
(7) Gomez-Pinilla F, Hillman C (January 2013). "The influence of exercise on cognitive abilities". Compr. Physiol. 3 (1): 403–428. PMC 3951958 Freely accessible. PMID 23720292. doi:10.1002/cphy.c110063.
(8) Guiney H, Machado L (February 2013). "Benefits of regular aerobic exercise for executive functioning in healthy populations". Psychon Bull Rev. 20 (1): 73–86. PMID 23229442. doi:10.3758/s13423-012-0345-4.
(9) Erickson KI, Miller DL, Roecklein KA (2012). "The aging hippocampus: interactions between exercise, depression, and BDNF". Neuroscientist. 18 (1): 82–97. PMC 3575139 Freely accessible. PMID 21531985. doi:10.1177/1073858410397054.
(10) Sabia S, Dugravot A, Dartigues JF, et al. Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study. BMJ (Clinical research ed 2017;357:j2709.

Competing interests: No competing interests

20 August 2017
AHMED R. ALIBRAHIM
Internal Medicine Resident
Department of Medicine, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia