The recently published Whitehall ll study, which focused on 7,000 British civil servants over a 10 year period, showed that amongst this group mental dexterity and brain power deteriorated earlier than was once thought.
There is no doubt that here in the Western world we are, on average, living longer, which creates an associated risk of age-related decline in our mental powers – but the news is not all bad. It was once thought older people lose thousands of brain cells every day, but this has now been contradicted by more recent studies. While neurons in some areas of the brain, like the basal forebrain, do decrease in number as we age, most neurons in the cortex are retained – while the hippocampus is capable of generating new cells until the day we die, if stimulated. Cell process can change, but this fine-tuning may result in gains in wisdom and patience.
While there is a sense of ‘use it, or lose it’ there are some effects of ageing on the brain that we can’t escape, because our bodies are deteriorating too. Our sensory organs – eyes and hearing, in particular – tend to deteriorate, too and with it the inclination to expose ourselves to new stimuli. The decline of other body systems will also have a similar effect. Our digestive system, for example, becomes less efficient at absorbing the nutrients we need from the food we eat, while the endocrine system becomes less efficient at responding to hormonal messages. Brain cells are also extremely sensitive to oxygen levels and, with a degree of arteriosclerosis typical of the ageing process, a reduced blood supply to the brain reduces the oxygen supply. A low-level but continuous oxygen deficiency will lead to a decline in neurons.
Without continuous external stimulation, new brain cell production slows down and with it brain plasticity because, as research has shown, it is the plasticity of the new brain cells that helps old brain cells function better. Neuroplasticity refers to the continued changes that can occur in the brain as the result of exposure to new experiences and learning opportunities, referred to by neurologists as ‘experience-dependent plasticity’. This was seen to occur after injury to the brain, where plasticity allowed new functional and structural changes to take place to compensate for the damaged area. This is what makes rehabilitation so important, and creates the possibility for regaining some, if not all, previously damaged function.
It was previously thought that the adult brain was hard-wired and no longer capable of new development. It had been thought that after critical periods of development, there would be no more change and that the sensory pathways were fixed, even while areas like the hippocampus – concerned with processing memory – continued to produce new neurons. Exposed to enough opportunities, it seems, we go on learning, process what we learn, and apply that learnt experience – all of which encourages the formation of new neurons in the hippocampus.
As we age, we tend to be exposed less to new experiences, become less active, and become less sociable so our opportunities, unless actively sought, for brain stimulation quite naturally decline. We are just less likely to try new things, so overall our opportunities for external stimuli decrease. But when older people are given tests that depend on vocabulary, general information and well-practised activities, they show negligible age-related deterioration. So while both low response times and short-term memory impairment contribute to lower scores on standard tests of intelligence for the elderly, removing this difference equals this out.
The Whitehall study shows that reasoning, memory and verbal fluency were the three main areas of cognitive ability affected. But when I read the following from India Knight’s piece in the Sunday Times on January 8th 2012, describing what she was trying to do all at the same time, one could perhaps see why: “How can we be expected to remember anything at all, when we are multi-tasking to such an insane degree?” she wrote. “As well as wondering what to write about, I was also thinking about my elder son’s university offers; my younger son being late for school; how to re-hang the door of a kitchen cabinet that has come off its hinges; where to collect my daughter from… what to make for supper… I was also on Twitter, having six conversations at once and reading hundreds more, and the doorbell rang twice…” and so she goes on.
Six things that might help:
· stop multi-tasking, focus on one thing at a time
· eat nutritiously 3 times a day, sit down and relax while eating
· exercise – even a daily, 20 minute walk in natural daylight will help
· anxiety & depression create additional stress hormones that are neurotoxic: so address the worries in your life & learn to let go
· maintain good relationships with people you actually see & talk to
· sleep – good restful sleep is restorative, make it a priority every night