Digest №22: On the Biological Importance of Enjoying Life as a Human

Bless!

It's popularly known – or presumed in a tongue-in-cheek way –, that the best way to live longer is to be stress-free and enjoy life. There's a surprisingly large body of evidence indicating this in the broad human population, that shows us, that social connection and subjective wellbeing and enjoyment of life are quite significant predictors of longevity.^1–4

Now, granted the quality of evidence is mixed, as interventional or mechanistic studies are somewhat hard to come by as they would need extremely long follow-up times, constant tracking, and couldn't ethically be made interventionary.

Nonetheless, thus far the evidence seems to indicate rather clearly, that whilst social connection and subjective life enjoyment aren't the only predictor of longevity, they seem to have some influence on human longevity. Proposed mechanisms aren't mutually exclusive and include such things as chronic stress, inflammation, neuroendocrine disruption, immune function, as well as various behavioural changes wrought by social contact or subjective enjoyment.

To limit the scope of this digest, we'll focus on the effect of chronic stress on cancer patient survival – both from an epidemiological and mechanistic perspective, as both are necessary to approximate the validity of the observed effects. Epidemiology tell us something of a putative effect in a population – for example, increased levels of cortisol may be correlated with shorter survival –, whilst mechanisms provide putative causal connections between the putative causes and effects in the population.

Without mechanistic data to support and elucidate our epidemiological observations, the latter is completely and utterly useless. After all, if we were to take epidemiological (correlational) evidence alone, then the popularity of the first name Christopher must have an effect on burglaries in Oklahoma or the number of UFO sightings in South Carolina must have something to do with the total number of successful Mount Everest climbs.^5–6

Both are very obviously preposterous, even though epidemiology would lead us to nonsensically believe them, if we took correlation as anything of higher value than a spur to begin looking into a certain topic more deeply.

Let's start with a very interesting observation. In a study looking at the influence of social support on outcomes of cancer patients, the authors discovered that satisfaction with social support had a more significant effect upon patient outcomes than did a measure of the objective amount of social support.⁷

Thinking more deeply about human nature and the stark inter-individual we exhibit, this shouldn't be too much of a surprise. Whilst we all do have social needs, the way we fulfil them can be starkly different from person to person. Consequently, a higher objective amount of social support may thus stress some of us and help others.

Circadian rhythms, cortisol levels, and the immune system interact in many complex ways.^8–11 It thus shouldn't be much of a surprise, that chronic stress, which is a psycho-physiological state of disordered regulation of stress hormones – such as cortisol and adrenaline – can negatively impact immune regulation and thus enable cancer to more easily evade immune destruction.

The effect of stress seems to be so significant, that patients with higher levels of evening cortisol die sooner, than those with lower levels of evening cortisol.¹² Given the above mentioned mechanistic connection between circadian rhythms, immune regulation, and stress hormones, I think it likely, that the observation of evening cortisol having a negative effect upon cancer patient survival actually does hold water.

As we also know from above, that subjective satisfaction of social support has an impact on cancer patient outcomes, I think the one conclusion you can draw from this here digest is to build yourself a life you enjoy on all levels – personally, socially, and spiritually. At the end of the day, few of us want to hear it, but we must all die at some point, and it seems, that enjoying life simply gives us more of what we enjoy.

Enjoy life and live brazenly toward better health.

God bless,
Merlin L. Marquard