Physical fitness linked to lower cognitive impairment in dementia

Dr Eddy Davelaar from the Department of Psychological Sciences discusses the importance of physical fitness in offsetting cognitive impairment in adults with dementia.

 

Dementia and cognitive impairment cost the UK economy approximately £26 billion per year. The number of people with dementia in England and Wales has been projected to increase by 57% from 2016 to 2040, primarily because of extended life expectancy. Finding ways to slow its severity and progression could have life-changing effects for the 800,000 people estimated to be living with dementia in the UK.

With the increased incidence in dementia, people are interested to know whether it could be prevented through changes in their lifestyle, such as eating habits, exercise, and decreased environmental stress. Research does suggest that a healthy lifestyle lowers the risk of dementia. We were interested in physical fitness as one of the lifestyle factors. In our recent article published in Frontiers in Public Health, we asked the question of whether self-reported physical fitness is associated with cognitive, or thinking ability in people with dementia.

To assess this, we used a cross-sectional design with two groups. The first group was made up of 30 older individuals (aged 65+ years) with dementia, who were attending the Alzheimer’s café social events. Those people in the dementia group have lower cognitive performance than the 40 age-matched participants from our control group, who do not have dementia.

We tested everyone on a wide range of cognitive tests, such as verbal fluency, prospective memory, and clock drawing. We also administered a 15-item questionnaire on physical fitness, which asked about strength (eg. ability to lift things), balance, and aerobic conditioning (eg. taking a brisk walk or taking the stairs instead of lifts). Many studies have shown strong correlations between self-report and objective measures of physical fitness. In addition, this questionnaire is available to everyone for self-assessment.

Our findings showed that in the group of dementia patients, those with greater physical fitness also had a greater general cognitive ability. Even those patients with the best cognitive performance still performed worse than the healthy individuals, who did not show this link between physical and cognitive fitness. Thus, physical fitness seems to buffer dementia-related cognitive deterioration.

We ran a number of checks on the results and found that the association did not change when we controlled for the age of the participants, the number of years since dementia diagnosis, the type of dementia, or even whether the person used to be physically active when they were younger. The latter finding suggests that the current state of being physically fit and capable is key to observing this cognitive benefit.

There are at least two explanations for these findings. First, the cardiovascular hypothesis states that physical activity stimulates blood circulation in frontal-striatal circuits (neural pathways that connect frontal lobe regions with the basal ganglia that mediate motor, cognitive, and behavioural functions within the brain), that are critical in executive functioning, such as planning and reasoning.

A second hypothesis suggests that physical fitness measures, such as strength and balance, require efficient brain representations of motor plans. The processes by which these motor representations become more efficient also leads to enhanced cognitive representations. Both hypotheses underscore the expression, ‘what is good for the heart is good for the brain’.

We are currently in the process of addressing the question of whether physical fitness (using both self-report and objective measures) is associated with cognitive decline or cognitive impairment in the absence of dementia. This would assess whether greater physical fitness is associated with greater mental fitness in general, or with cognitive fitness specific in the context of dementia.

Future research could also extend this work using longitudinal study designs in order to address the question of whether a change in physical fitness is associated with a change in the risk of dementia, which has important implications for health policy and age-appropriate physical intervention programmes for both healthy individuals and dementia patients.

Read the original, peer-reviewed article: Increased Physical Fitness Is Associated with Higher Executive Functioning in People with Dementia (2017).

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The Myth of the Optimism Bias?

This article was originally posted by ‘Neuroskeptic’ on DiscoverMagazine.com on 3 June 2016. The article discusses research on optimism bias, as carried out by a team of psychological researchers including Birkbeck’s Professor Ulrike Hahn.

OptimismAre humans natural, irrational optimists? According to many psychologists, humans show a fundamental optimism bias, a tendency to underestimate our chances of suffering negative events. It’s said that when thinking about harmful events, such as contracting cancer, most people believe that their risk is lower than that of ‘the average person’. So, on average, people rate themselves as safer than the average. Moreover, people are also said to show biased belief updating. Faced with evidence that the risk of a negative outcome is higher than they believed, people don’t increase their personal risk estimates properly.

But now a group of researchers, led by first author Punit Shah of London, hascriticized the theory of biased belief updating and, by extension, the whole optimism bias model. Shah et al. say that optimism bias may be a mere statistical artifact, a product of the psychological test paradigms used to assess it. They argue that even perfectly rational, unbiased individuals would seem ‘optimistic’ in these tests. Specifically, the authors say that the apparent optimism is driven by the fact that negative events tend to be uncommon.

The new work builds on a 2011 paper by Adam J. L. Harris and Ulrike Hahn, also authors of the present paper. The 2011 article criticized the claim that people show an optimism bias by rating themselves as safer than the average. The new paper takes aim at biased belief updating. Here’s how Shah et al. describe their argument:

New studies have now claimed that unrealistic optimism emerges as a result of biased belief updating with distinctive neural correlates in the brain. On a behavioral level, these studies suggest that, for negative events, desirable information is incorporated into personal risk estimates to a greater degree than undesirable information (resulting in a more optimistic outlook).

 

However, using task analyses, simulations and experiments we demonstrate that this pattern of results is a statistical artifact. In contrast with previous work, we examined participants’ use of new information with reference to the normative, Bayesian standard.

 

Simulations reveal the fundamental difficulties that would need to be overcome by any robust test of optimistic updating. No such test presently exists, so that the best one can presently do is perform analyses with a number of techniques, all of which have important weaknesses. Applying these analyses to five experiments shows no evidence of optimistic updating. These results clarify the difficulties involved in studying human ‘bias’ and cast additional doubt over the status of optimism as a fundamental characteristic of healthy cognition.

I asked Shah and his colleagues to explain the case against the optimism bias in belief updating in a nutshell. They said

All risk estimates have to fit into a scale between 0% and 100%; you can’t have a chance of getting a heart attack at some point in your life of less than 0% or greater than 100%. The problems for the update method arise from the fact that the same ‘movement’ in percentage terms means different things in different parts of the scale.

 

Someone whose risk decreases from 45% to 30% has seen their risk cut by 1/3, whereas someone whose risk increases from 15% to 30% has seen their risk double -much bigger change. So the same 15% difference means something quite different if you have to revise your beliefs about your individual risk downwards (good news!) or upwards (bad news!) toward the same percentage value. The moment people’s risk estimates are influenced by individual risk factors (a family history of heart attack increases your personal risk by a factor of about 1.6), people should change their beliefs to different amounts, depending on the direction of the change. The update method falsely equates the 15% in both cases.

 

If the difference in belief change simply reflects these mathematical properties of risk estimates then one should see systematic differences between those increasing and those decreasing their risk estimates regardless of whether they happen to be estimating a negative or a positive event. But in the first case, this will look like ‘optimism’, in the second case it will look like ‘pessimism’. This is the pattern our experiments find…

 

The evidence base thus seems far less stable than previously considered. There is, using various paradigms, plenty of evidence for optimism in various real-world settings such as sports fans predictions and political predictions, but these just show that certain people might be optimistic in certain situations, not that there is a general optimistic tendency across situations that would be required to say people are optimistically biased. It is also important to note that because this belief updating paradigm has been used in so many neuroscience studies, it means those neuroscience data are also uninterpretable.

Read the original article on DiscoverMagazine.com

Read the original article on DiscoverMagazine.com

In my view, Shah et al. make a strong case that the evidence for optimism bias needs to be reexamined. Their argument makes a crucial prediction: that people should show a ‘pessimistic’ bias (the counterpart of the optimism bias) when asked to rate their chance of experiencing rare, positive events. In the new paper, the authors report finding such a pessimistic bias in a series of experiments. But perhaps they should team up with proponents of the optimism bias and run an adversarial collaboration to convince the believers.

  • Punit Shah, Adam J. L. Harris, Geoffrey Bird, Caroline Catmur, & Ulrike Hahn (2016). A Pessimistic View of Optimistic Belief Updating Cognitive Psychology
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Make fear your friend

This post was contributed by Professor Naz Derakhshan of Birkbeck’s Department of Psychological Sciences

 

“Fear is often thought of as a negative emotion, but a new idea in psychology suggests that using it the right way can turn it into an incredibly positive force in your life.”

 

So starts a three page health feature article in the February edition of Top Sante. Showcasing the expertise of Birkbeck’s Prof Naz Derakhshan, the article posits that  fear can be turned into a positive force in our lives – all we need to do is listen to it, trust in it, and learn from it. In other words, we need to befriend it.

“Instead of thinking of fear solely as a negative emotion, embrace it as an
important warning system,’ says Professor Derakhshan in the article. “Being afraid of something is a signal that its consequence is important to you so it should be attended to.”
Click below to read the full piece, which includes some handy tips on how to welcome fear as a positive friend in your life, and how to ultimately become its boss.
Make Fear Your Friend - page 1 (article copyright of Top Sante)

Make Fear Your Friend – page 1 (article copyright of Top Sante)

 

Make Fear Your Friend - page 2 (article copyright of Top Sante)

Make Fear Your Friend – page 2 (article copyright of Top Sante)

 

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