There’s a fascinating correlation between brain health and bone health. In theory they don’t have much in common, do they? But research published earlier this year revealed low bone mineral density is linked to higher dementia risk later in life. Of course, this doesn’t mean one causes the other: correlation, as we always say, is not the same as causation. But it is a useful reminder that we need to look after both. In this particular study, a team from The Netherlands followed three and a half thousand people, with an average age of 72, for just over a decade. Around half the study participants were women. The researchers found that low total bone density, and lower bone mineral density in the femoral neck (the area around our hip joints) were linked to increased dementia risk.
The first question you’re going to asking is, why is that? What’s the link? The honest answer is that we can’t be sure whether low bone density causes dementia, or dementia causes low bone density, or bone density and dementia share a common risk factor. My hunch would be that it’s the latter.
HOW LIFESTYLE HELPS…
We know, of course, that our risk of both low bone density and dementia can be influenced by lifestyle. A good diet, plus exercise, will reduce our risk of either of these conditions.
All the wonderful things we can do to protect our bones, also protect our brains – and vice versa. We’ve written at length about exercise to support our bones, – you can read that here. A simple squat is one of the best all round exercises we can do. Annabel does two minutes of squats each day, I do them between calls and emails as I work (from home – not sure I’d squat in an office!) Research published earlier this year linked stronger legs to better brain health, and the resistance exercise we need to build muscle also strengthens our bones. We’ve got some great recipes in the archives that provide nutrients to support both brain and bone health, like this simplest-ever fish pie, and kale shakshuka.
…AND NOT JUST DIET AND EXERCISE
It’s not just diet and exercise we need to focus on when it comes to brain and bone health. Scientists have known for a while that social isolation is a driver of the ageing process. As we wrote in our book The Age-Well Project, a study by the Royal College of GPs found that those suffering from loneliness are 50% more likely to die prematurely, making loneliness as big a mortality risk as type-2 diabetes. We also know that social isolation is a key modifiable risk factor for dementia. Now new research, published this summer, has linked social isolation to low bone density. The research was done on mice, rather than humans, but we share many of the same genetic characteristics. When mice were put in cages by themselves for four weeks, they experienced reductions in bone mineral density. This was particularly true of male mice, although the female mice did have increased bone reabsorption, which is linked to fracture risk. We know that stress is a risk factor for osteoporosis and poor bone health, so it does, unfortunately, make sense that isolation could also have an impact.
THE ROLE OF OESTROGEN
For women, there’s another powerful force at play when we think about our brain and bone health. We know that oestrogen protects both pre-menopause. When that oestrogen declines our brains and bodies are more vulnerable to decline themselves.
Oestrogen is so much more than a hormone of reproduction – we have receptors for it throughout our bodies. This is an extremely reductive way of looking at it, but during our reproductive years, oestrogen wraps us in a protective cloak, keeping us healthy so we can have babies to perpetuate the species. Which makes sense from an evolutionary standpoint.
Estradiol – the type of oestrogen in our bodies pre-menopause – is our self-made wonder-drug. It supports bone growth promoting the activity of osteoblasts, the cells which make new bone. It also increases cerebral blood flow and stimulate the production of new neurons. I go into this more in my book The Power Decade: how to thrive after menopause.
The important thing to remember is that when this wonderful protector declines, putting in the work to look after ourselves becomes non-negotiable. There’s no plan B! Protecting our health needs to be the foundation of anything else we want to do. How do you look after your brain and your bones? Let us know in the comments below.