What is cognitive health?
Cognitive health describes the ability to learn, think and remember. Not surprisingly, cognitive health is a key component of healthy ageing as it is vital in maintaining a good quality of life and the independence to perform everyday activities.
The human brain has approximately 100 billion neurons which are connected at trillions of touchpoints to make up a “neural forest”. These neurons or nerve cells communicate amongst themselves and the rest of the body. The neural forest is responsible for the approximately 12,000 to 60,000 thoughts you have each day. While most of these neural pathways are formed into our 20s they can continue in certain parts of the brain until the day we die. This is called neuroplasticity. Various areas of cognitive health include executive function (organising and decision making), language and memory. The development, peak and decline of cognitive health differs across the lifespan.
The brain is the only human organ that undergoes development for such a long time. The good news is that at almost any age some specific cognitive functions are peaking. The not so good news is that this happens while other areas of cognitive function are declining. Overall, after building cognitive function into adulthood, these tend to naturally decrease with age regardless of which specific function. Therefore, understanding the natural pattern of cognitive health across the lifespan and how we can potentially improve this is of interest for maintaining an excellent quality of life as we age.
Cognitive health changes across the lifespan
Cognitive abilities increase dramatically from infancy to young adulthood. The average baby’s brain is about 25% that of an adult. Amazingly, the brain doubles during the first year of life, is about 80% of adult size by 3 years and 90% by age 5 years. It is not surprising then that there is such a high demand for nutrients important for cognitive development at this time. However, different types of cognitive functions peak at different ages. For example, while brain speed and processing power tends to peak at 18 years of age, basic mathematical ability is best at age 50. Likewise, the acquired knowledge (general knowledge) part of cognitive health tends to steadily improve until the age of 60 years where it remains relatively stable until 80 years and then sharply declines.
Yet other types of cognitive function such as autobiographical events remain fairly stable with advancing years. That is why someone can describe a vivid memory from their childhood but finds it difficult to remember what they did yesterday. Procedural memories, such as remembering how to play the piano or ride a bike are also preserved into old age.
(Cadar D. Cognitive Ageing. 2018. DOI: 10.5772/intechopen.79119. https://www.intechopen.com/books/geriatrics-health/cognitive-ageing)
- Maternal and childhood nutrition
Recent research highlights the link between early life nutrition and cognitive health across the lifespan. The mother’s diet preconception, in utero and during postnatal life can influence cognitive impairments and brain ageing for the entire lifespan of the offspring.
The human brain has a very high demand for nutrients in this early period and nutritional imbalances affect normal neurodevelopment resulting in lasting cognitive deficits. If nutrition isn’t provided in sufficient amounts in utero it may be taken instead from the mother which can lead to deficiencies in both mother and developing baby causing cognitive decline later in life.
The human brain is 60% fat. Therefore, one of the greatest nutrients of interest during this period to maximise cognitive health is omega 3 fatty acids found in oily fish like salmon and algae. These fats help to stabilise the brain cell walls.
Human neurodevelopment at cellular level (Gilmore JH, Knickmeyer RC, Gao W. Imaging structural and functional brain development in early childhood. Nat Rev Neurosci. 2018;19(3):123-137.)
(Gilmore JH, Knickmeyer RC, Gao W. Imaging structural and functional brain development in early childhood. Nat Rev Neurosci. 2018;19(3):123-137.)
One of the key aspects of cognitive health during the adult years is to optimise cognitive performance. This optimisation helps with different stages of adult life, such as studying, beginning a career, starting families, and coping with a developing career while raising young children.
A healthy, anti-inflammatory diet consisting of fruits, vegetables, legumes, fish, lean meat and dairy or vegetarian alternatives and moderate amounts of good fats has been associated with better cognitive health. Various dietary patterns like the Mediterranean style of eating has also been associated with decreased rates of dementia.
- Older Adults
It is important to ensure that our ageing years focus on maintaining cognitive health and slowing down cognitive decline for best quality of life. The aim is to maintain cognitive performance by remaining physically and mentally active as we round off our careers, look after grandchildren and start retirement. Nutrition should focus on anti-inflammatory components including fish oil and antioxidants.
Preventing declines in cognitive health
Encouragingly, lifestyle factors such as good nutrition, physical activity, not smoking, limiting alcohol consumption and stress management can improve cognitive health at any age. It is likely that the most beneficial support options to maintain cognitive health into our golden years is a combination of nutrition, exercise, meditation and other lifestyle factors in a coordinated manner.
As our life expectancy increases it is vital that our cognitive health is optimised to maintain quality of life and functional independence. While overall cognitive health tends to decrease with age, especially after 80 years, it can be enhanced by specialised nutrition and lifestyle factors. Not only is the nutrition of the mother vital for the brain health of the developing child but is also associated with long term cognitive health of the offspring. Encouragingly, neuroplasticity and new connections within the brain don’t just occur in childhood but throughout life. Certain nutrients including omega 3 fatty acids found in a healthy diet and specialised nutrient supplements can help improve aspects of cognitive health. Optimising cognitive health into our later years will have positive benefits on quality of life and functional independence.
Kirby A and Derbyshire E. Omega-3/6 fatty acids and learning in children and young people: a review of randomised controlled trials published in the last 5 years. J Nutr Food Sci 2018; 8:2.
Spencer SJ, Korosi A, Layé S, et al. Food for thought: how nutrition impacts cognition and emotion. npj Sci Food 2017; 1(7).
Murman DL. The impact of age on cognition. Semin Hear. 2015; 36(3): 111–121.
Chen X, Maguire B, Brodaty H, et al. Dietary Patterns and Cognitive Health in Older Adults: A Systematic Review. J Alzheimers Dis. 2019;67(2):583-619
Rakesh G, Szabo ST, Alexopoulos GS, et al. Strategies for dementia prevention: latest evidence and implications. Therapeutic Advances in Chronic Disease. 2017:121-136.