Lack of exercise and poor nutrition could directly increase risk of diseases like dementia, study shows

An unhealthy lifestyle can increase the risk of diseases such as dementia by slowing the rate by which new brain cells are produced, according to a new study.

Both poor diet and lack of exercise can influence the risk of cognitive decline (CD) and dementia by potentially influencing hippocampal neurogenesis long before the onset of the diseases, researchers found at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London.

Previous studies have shown that diet and exercise have some protective effects against CD and dementia, but the IoPPN’s new study sheds more light on how malnutrition and lack of exercise can directly reduce the growth of new cells.

Adult hippocampal neurogenesis is important for learning and memory and it is affected in diseases that include cognitive impairment, depression, and anxiety.

Scientists believe that the findings of the study could form the basis of an “effective early preventative strategy against CD and dementia”.

Rates of cognitive decline and dementia are expected to triple in prevalence by 2040. According to Alzheimer’s Research UK, there were 525,315 people living with a dementia diagnosis in the UK last year.

Altered neurogenesis in the brain could potentially act as an early biomarker for both CD and dementia, according to the IoPPN’s research.

Scientists studied blood samples of 418 adults over the age of 65 in France, that were collected 12 years before diagnoses of CD and dementia had been made.

Information on each participant’s socio-demographic group, lifestyle, and clinical data were collected. The numbers of people whose cognitive condition had changed or who had developed dementia were recorded every two to three years over the 12-year period.

The blood samples were also tested on human hippocampal stem cells to see if they influenced neurogenesis in lab settings, and whether diet and exercise were important factors.

Cognitive degeneration was associated with levels of neural stem cell death 12 years prior to diagnoses of CD and Alzheimer’s – researchers found over the course of the study.

The team also found that exercise, nutrition, and levels of vitamin D, carotenoids and lipids are all associated with the rate at which cells die.

Physical activity and nutrition were key factors that then also determined CD status. Specifically, researchers found that reduced physical activity and increased malnutrition both increased cell death, which in turn increased the risk for future CD.

Dr Andrea du Preez, the study’s first author from IoPPN said: “While more work is undoubtedly needed to fully understand how diet and exercise might modulate hippocampal neurogenesis, our findings may represent an effective early preventative strategy against CD and dementia.”

The study has been published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.