Friendship — Part 4

Indeed, when studies measure it, marital satisfaction is a much stronger predictor of happiness than just being married and, unsurprisingly, being in a toxic relationship is decidedly bad for happiness. Single people who elect to never marry but have strong social support through other means are certainly happy and happiness increases when low-quality marriages dissolve. This is true for both men and women. People who stay in relationships that turn sour in order to preserve the ideal – for the sake of appearances, for kids or for basic sustenance – may be married but it hurts both their happiness and their health. Altogether, decades of research on human development, psychology, neuroscience and medicine irrefutably converge on this conclusion: being in a long-term, committed relationship that offers reliable support, opportunities to be supportive and a social context for meaningful shared experiences over time is definitely good for well-being.

Friendship requires risk and commitment but the lifetime rewards that accompany inner-circle ties make the risks and time demands worthwhile. In one decades-long Harvard University study, people who enjoyed strong social bonds into their eighties were less likely to succumb to late-life cognitive decline and dementia. Researchers at Michigan State University tested which aspects of social relations were most associated with memory or remembering in over 10,000 people whose ages ranged from 50 to 90. Participants were tested at two-yearly intervals for six years. Being married or partnered, having more frequent contact with children and friends and experiencing less strain within relationships were each independently associated with cognitive functions such as better memory and less memory decline over time. So the clear message is that frequent quality relationships are good for the brain.

Chapter 3: Friendship

I do want to stress at this juncture that worry about getting dementia, particularly as people develop memory problems, is something I encounter daily and I understand the need for reassurance. Not all memory problems indicate dementia and most deterioration in memory or remembering is age related, very common and does not progress to dementia. Cognitive functions refer to multiple mental abilities that we use regularly throughout the day, such as learning, thinking, reasoning, problem solving, decision-making and concentration. Loneliness and isolation cause a decline in all of these mental abilities Social engagement, connections with family and friends and participation in activities and organisations protect against poor cognitive functioning and dementia. What is the biological explanation for the relationship between friends and the brain? In 2019, colleagues at University College, London conducted a large review of the published literature exploring the effect of three lifestyle factors on cognitive function and dementia: social networks, physical leisure and non-physical activities. They then summarised all of the evidence, taking into account the limitations of the studies and their biological plausibility. A beneficial effect on brain function and mental abilities and a protective effect against dementia were evident in all three lifestyle components. All seemed to share common pathways, rather than having specific separate pathways, which converge within the three major theories for why we get dementia: the cognitive reserve hypothesis, the vascular hypothesis and the stress hypothesis. We will dwell briefly on each to better understand why friendship changes brain health and why this matters from early adulthood onwards.

Chapter 3: Friendship

Let’s start with an experiment in rats to better explain the cognitive reserve theory. Cognitive reserve implies that we have ‘banked brain capacity’, which is not always used but can be called upon if needed, just like a lifelong savings account in the bank. Environmentally enriched conditions for the rat are equivalent to conditions in the wild, with plentiful opportunities for physical activity, learning and social interaction – rat utopia. Rat utopia prevents cognitive problems in adult rats by building up the rat’s brain’s ‘savings account’ – that is, by storing up cognitive reserve. Conversely, an impoverished environment of loneliness and low activity in rats is linked to impaired brain function. The good news is that this is partly reversible by enriching impoverished environments.

Both human and rat brains have the capacity to form new brain cells, new blood vessels and new communication bridges between brain cells throughout life, all of which constitute brain reserve. Mental stimulation, such as that provided by social contacts, physical exercise and creativity, increases the formation of these structures and therefore of reserve. New brain cell formation and therefore cognitive reserve happens predominantly in three key brain areas: in the hippocampus, which sits on each side of the brain and converts short-term memory to long-term memory; in the olfactory bulb, which is at the front of the brain above the nose and governs our sense of smell and in the cerebral cortex, which is important for concentration, understanding, awareness, thought, memory, language and consciousness. So new brain cell formation and cognitive reserve pretty much covers most of our important brain functions. MRI brain scans confirm that people with higher cognitive reserve, due to mental stimulation from social contacts, tolerate more brain pathology. This means that despite having dementia pathology – i.e., abnormal proteins in brain cells – they do not have signs of dementia and live life apparently with normal brain function because they have more ‘reserve capacity’ to call on.

Chapter 3: Friendship

Social, mental and physical stimulation through friendships and relationships also act via the vascular system. High blood pressure, high cholesterol, irregularities of the heart – particularly atrial fibrillation in mid-life – are all associated with Alzheimer’s dementia in later life. Social engagement and relationships reduce these vascular diseases, which in turn reduce vascular causes of dementia and further explain why social contacts protect the brain.

Relaxation and stress reduction are the third explanation for the link between social friendship and dementia. Active individuals with frequent contacts and opportunities to engage with others are more likely to have positive emotions such as high self-esteem, social competence and good mood, all of which lower stress and stress hormones. A higher susceptibility to stress doubles the risk of dementia by triggering chronically high cortisol levels. If you take nothing else from this publication other than a determination to build friendships, it will make a difference to your biological age and a difference to others whom you befriend.