What mental picture do you conjure up, when you think of elderly people? Do you picture frail, stooped, doddery ‘little old ladies’? Or ‘silly old buggers’ holding up the checkout line because they can’t work the EFTPOS device?
How about when you picture yourself as an elderly person? Do you imagine yourself playing with your grandchildren, travelling the world, and enjoying pastimes you never had time for when you were working and raising your own children?
Or do you see yourself as one of those doddery elderly folk, inexorably declining both physically and mentally until, like my 93 year old stepfather, you wake up each morning wishing that you hadn’t… or like my mother-in-law, who progressively lost her mobility, independence, ability to communicate, memories and her very personhood, in a tortuous 10 year descent into the hell known as vascular dementia?
Although most humans develop a fear of death as soon as we become intellectually capable of grasping what it means, I would argue that most people fear decline – especially a long drawn out period of decline – more than they fear death itself. Death, after all, is just a moment. Decline can take decades.
But are we doomed to failing physical and mental powers as we get older? It turns out that the processes that rob bodies of their strength and vigor are inextricably linked to those that rob minds of their sharpness, so, very conveniently, there are common solutions to both problems.
One of the mental functions that is particularly hard-hit by the normal aging process is known as fluid intelligence, which involves being able to think and reason abstractly and to come up with novel problem-solving strategies for situations that you’ve never encountered before.
This age-related decline in fluid intelligence is in turn linked to atrophy (shrinkage) in the anterior prefrontal cortex of the brain – the yellow-orange ‘bulge’ at the front of the brain in the diagram below – and deterioration in the integrity of white matter in the frontal lobe (the areas marked in yellow-orange and pale green below).
And these brain changes are in turn linked to increased body fat – in particular visceral adiposity, the accumulation of fat within the abdominal cavity.
While subcutaneous fat accumulates just under the skin, far from any metabolically important organs, visceral fat is stored around vital internal organs including the liver and pancreas.
Visceral fat releases chemicals which set off a chain of inflammation throughout the body, including the brain. This inflammatory damage initiated by excess belly fat is believed to cause the damage to the brain that results in diminished fluid intelligence.
Deteriorating brain function is also linked to a decline in muscle mass and strength. Working muscles release anti-inflammatory substances called myokines, as well as mitigating insulin resistance which is a driver of inflammation.
Researchers utilising data from the UK Biobank study, a prospective cohort study which recruited half a million Brits aged 40 to 79 in 2007, have now drawn all of these separate threads of scientific investigation into one cohesive strand, with an important message for anyone who wishes to enjoy their autumn years, with their marbles intact: Develop a healthy body composition (more muscle, less fat) and maintain it as you get older.
In a study titled ‘Aging-related changes in fluid intelligence, muscle and adipose mass, and sex-specific immunologic mediation: A longitudinal UK Biobank study‘, the researchers took data from a sub-cohort of 4431 UK Biobank participants who underwent DEXA scanning to assess their body composition (divided into lean muscle mass, total non-visceral adipose mass (predominantly subcutaneous fat) and visceral adipose mass.
These participants also underwent both blood tests and the Fluid Intelligence Test on 3 separate occasions.
When all the numbers were crunched, the researchers found that:
- Participants with higher lean muscle mass showed gains in performance on the Fluid Intelligence Test over time. This brain-protective effect of muscle mass was stronger in women than men (possibly because on average, men have significantly more muscle mass than women at all stages of life).
- Participants with higher fat mass – both visceral and non-visceral (subcutaneous) – showed declines in fluid intelligence scores over time.
- Higher body mass was associated with raised levels of c-reactive protein (CRP), a marker of systemic inflammation, although there was no association between CRP and fluid intelligence.
The researchers’ conclusions are well worth noting:
“Aging itself may not be deleterious, but rather age-related changes in body morphometry [lean vs fat mass] that are related to cognitive decline.”
I have been banging the drum for muscle-strengthening exercise, particularly in older women, for decades (see my previous articles Crossword puzzles or pumping iron – what’s best for maintaining your marbles? and Are you fit enough to save your brain?
When I ask my older clients about their current exercise habits, those who are active almost always nominate walking as their major form of physical activity. Walking is a delightful activity that has much to recommend it (it gets you outdoors, breathing [hopefully] fresh air and potentially meeting other people), but it is no way sufficient to maintain muscle mass – not to mention bone mass – as we get older.
Both men and women need to incorporate regular strength training into their weekly exercise routines. Examples of strength training include:
- Weight training, either with free weights (dumbbells, barbells, kettlebells, sandbags) or weights machines at the gym.
- Resistance bands and tubes.
- Bodyweight exercises such as squats, lunges, push-ups, sit-ups and chin-ups.
- Pilates using the Reformer exercise machine.
- Aquarobics, especially using foam dumbbells.
- Riding an exercise bike or using an elliptical trainer or rowing machine with the resistance cranked up. (Helpful hint: if you can read a magazine or scroll through your Instagram feed while exercising, you’re not working hard enough.)
- Battle ropes.
If you’re new to strength training, there are plenty of YouTube fitness channels and free workout videos to get you started. My personal favourite is Fitness Blender which allows you to customise your workout based on available time, fitness equipment, type of workout and difficulty level.
If you are rehabilitating an injury, or have never done strength training before and are feeling overwhelmed, I highly recommend seeing an exercise physiologist who can design a suitable program for you.
The bottom line: Research on the link between body composition and cognitive function underscores the truth of the old adage, ‘ Use it or lose it’. Human bodies were made to move – to walk, run, climb, lift, carry, dig, dance, drag (not to mention making love!) – and when we stop moving, it’s not just our bodies that decline.
The age-old contest between brawn and brains turns out to not be a contest at all. More muscle power equals more brain power, and the connection between the two becomes more important, the older we get.
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