Does a healthy diet protect your cognitive function as you age?
By Avance Care’s Registered Dietitian: Shannon Corlett, MS, RDN, LDN
Often the simplest questions come with the most complex answers and preservation of cognitive function is no exception. But with over half of adults reporting concern for their mental capabilities as they age, it is important to look at early interventions for brain health. A well-balanced diet and active lifestyle are the core structure for long-term health, but research has also investigated specific nutrients that may help to preserve cognitive function over time.
Memory loss is the primary symptom associated with dementia, but this diagnosis can also include difficulty with thinking, problem-solving, and language. There are many different types of dementia, separated according to the associated cause. For example, Alzheimer’s disease (AD) is the most common type of dementia and likely results from the buildup of proteins in the brain that cause ‘plaque’ and ‘tangle’ structures. This buildup of abnormal proteins prevents connections between nerve cells, leading to their death and ultimately a loss of brain tissue. In comparison, vascular dementia occurs when a narrowing or blockage of blood vessels results in reduced blood flow to the brain, damaging or destroying cells. With multiple potential underlying conditions, it can be difficult to isolate independent nutrients associated with risk reduction. Instead recommendations focus on minimizing inflammation and oxidative stress.
The Fine Print
Many individual nutrients, neurotransmitters, and hormones have been researched in relation to dementia, including but not limited to B Vitamins (specifically folate and B12), Vitamin D, beta-carotene, estrogen, insulin, phytochemicals (specifically resveratrol), acetylcholine, and omega-3 fatty acids. Each of these is thought to be Alzheimer’s disease-protective, but most of the current data in this field is observational and not able to be directly connected to disease prevention. However, many of these nutrients can be incorporated into a healthy diet or supplemented for individuals with dietary restrictions that limit intake to ensure that needs are being met.
In addition to adequate nutrient intake, there is also a growing body of research linking AD with insulin resistance. Although unresolved questions still exist, many of the biochemical features seen in AD overlap with those seen in diabetes mellitus. As diabetes is strongly linked with diet and lifestyle, this further supports the need to institute healthy living early in life, in addition to providing potential therapeutic interventions to improve cognitive outcomes.
The Big Picture
Beyond diet and lifestyle, dementia also has a genetic component. However, families with strong inheritance are rare because there are so many genes that can increase or reduce the risk of developing these conditions. Having a close family member with dementia or Alzheimer’s disease increases an individual’s risk for these conditions, but this risk can be reduced by maintaining a healthy diet and lifestyle. In particular, weight and activity have been found to have a direct connection with AD risk. Compared to individuals within a normal weight range, being underweight (BMI ≤18.5) increases risk of AD by about 36% while being obese (BMI ≥30) increases risk of AD by about 42%. Furthermore, individuals who are obese have a five times greater risk of developing vascular dementia. Exercise, in addition to impacting weight, also has a significant relationship with cognitive function. Regular physical activity during the middle of your life will decrease dementia risk by 30%, and this significance likely continues as you age. Both weight and physical activity are significant modifiable risk factor for the development of cognitive disorders, and all individuals (with or without genetic risk) should strive to maintain a healthy weight and active lifestyle.
As our understanding of dementia continues to grow, it can be challenging to differentiate what interventions are necessary to preserve cognitive function. However, there are some clear conclusions that can be made. There is no strong evidence that any one specific food prevents dementia.
Instead, it is a healthful diet pattern that may protect cognitive function. A diet high in flavonoids (plant based chemicals with antioxidant and anti-inflammatory properties) and unsaturated (omega-3 and omega-6) fatty acids has been associated with improved cognition. Focus on consuming a whole food diet that is minimally processed and combines fruits, vegetables, whole grains, legumes, healthy fats (ex. olive oil, avocado, nuts) and fish to meet nutrient needs. In combination with achieving a healthy weight and an active lifestyle, this is the recipe for long term maintenance of cognitive function.
 Mosconi L, Murray J, Davies M, et al. Nutrient intake and brain biomarkers of Alzheimer’s disease in at-risk cognitively normal individuals: a cross-sectional neuroimaging pilot study. BMJ Open. 2014;4(6):e004850
 de la Monte SM, Wands JR. Alzheimer’s disease is type 3 diabetes — evidence reviewed. J Diabetes Sci Technol. 2008;2(6):1101-1113
 Canevelli M, Lucchini F, Quarata F, Bruno G, Cesari M. Nutrition and dementia: evidence for preventive approaches? Nutrients. 2016;8(3):144