The researchers at Leicester University studied more than 500,000 Britons aged 37-73 who were given intelligence and memory tests.
They were actually looking at the effect of sedentary behaviour on brainpower. They found it fell faster among middle-aged people who drove long distances every day.
So middle-aged people should cut out that long-distance commute and find more socially stimulating things to do.
It was already known that sedentary behaviour was bad for your heart but now it appears to be bad for your brain too “perhaps because the brain is less active in those hours“ (I hope they weren’t referring to driving).
Cognitive decline can happen quickly “(It’s) decline is measurable over five years because it can happen fast in middle-aged and older people. This is associated with lifestyle factors such as smoking and bad diet – and now it’s time spent driving” said Kishan Bakrania.
93,000 of the participants who were already driving two to three hours a day had lower brainpower when the research started – and it continued to decline and faster than people who did little or no driving.
Similar results were found with TV watching. Those who watched 3 hours a day had lower brainpower at the start of the research and it fell faster over five years.
Although studies are suggesting that cognitive decline is linked to physical inactivity using a computer at work or for playing games actually stimulates the brain – whereas watching TV doesn’t. However sedentary behaviour is also linked with obesity, Type 2 diabetes and cardiovascular problems. So get off that couch!
The research results were no surprise to the Alzheimer’s Society. Cardiovascular health will affect memory and thinking skills and “staying mentally and physically active hips keep the brain healthy“.
Economic researchers in Japan (where there is a culture of long hours and karoshi – death by overwork) analysed the employment habits and cognitive test results of 3,000 men and 3,500 women above the age of 40 in Australia, including retired and unemployed people.
They found that a part-time job is the best balance between keeping the brain stimulated and becoming completely exhausted through stress.
People who worked about 25 hours a week tended to get the best scores. Those who didn’t work at all scored about 20% lower on the series of tests (reading, numbers and patterns).
Working 40 hours a week was linked to a slightly smaller cognitive deficit but working 55 hours or more was worse than being retired or unemployed.
Working over 50-55 hours is known to cause heart problems in men in particular and an increase in error rates and accidents. The Whitehall study of 10,000 civil servants also found that people who worked working 55 hours a week did worse on cognitive tests than those who kept to 40 hours. Despite this body of knowledge the UK government still opted out of the European Working Time Directive.
Many countries have extended or scrapped the state retirement age and many people face the prospect of working into their 70s. Finnish experts have already warned that people may not be physically or mentally capable of sustaining the effort required to continue in their jobs.
Some companies , like BMW, have invested in modifying the workplace to cater for older employees but they are probably an exception.
Marianna Virtanen, a Finnish Occupational Health expert (they are hot on OH in Finland) who led the Whitehall studies in the mid-80s said that the new research seemed to show tat “Middle-aged and older people should limit their working hours to keep their cognitive capacity fit“.
She did wonder whether a long working week caused a drop in cognitive ability or whether a drop in cognitive ability led to people working longer hours to compensate. She conceded however that “In certain jobs where there is a lot of intense focus and concentration is needed, working long hours may be more exhausting to cognition“.
Researchers have found that working on complex tasks which require a lot of brainpower protects your thinking skills in later life.
Teaching, managing people, dealing with complicated data and similar work helps the brain to remain sharp after the age of 70.
Over a 1,000 people from the Lothian birth cohort of 1936 who had been tested in the Scottish Mental Health Survey of 1947 were tested for memory, mental processing speed and general thinking ability by researchers at universities in Edinburgh.
They then assessed the complexity of their jobs using the Dictionary of Occupational Titles, They found that those who had worked in difficult jobs had an advantage.
Professor James Goodwin, head of research at Age UK said “The relationship between work we do during our lives and our health in later life is a complex one so this finding is a welcome step forward ….. the more we can find out what influences cognitive ageing, the better advice we can give”.
The study was published in Neurology, the medical journal of the American Academy of Neurology.
As I’ve said before intelligence is not that straightforward. We used to think IQ was about 50% inherited and then recognised the impact of upbringing which started the nature-nurture debate.
Geneticists discovered that your genes could also be influenced by environmental factors – epigenetics – but also that people who were assumed to have inherited certain skills probably got them through hard work.
Other recent research show that high IQ scores are as a result of innate intelligence PLUS motivation (See posts on intelligence). That means you can improve your scores if you really want to.
It is clear now that there is no single gene for intelligence and the latest research at the University of Edinburgh shows that about 40% of the variation in knowledge (crystalline type intelligence) and about 50% of differences in problem-solving skills (fluid type intelligence) are due to genetic factors.
Scientists still can’t tell you exactly which genes have an effect on intelligence but have found broad patterns. Research like this could help to understand how people suffer cognitive decline in old age (See: Can you keep Alzheimer’s at Bay?).