Don’t let your heart rule your head
Large scale study to test mental agility confirms that the same risk factors involved in cardiovascular health problems is also involved in impaired cognitive function
Cognitive decline is often accepted as an inevitable part of aging. Even aside from specific conditions such as Alzheimer’s disease, poor short term memory and impaired reasoning abilities can be among the problems that come with older age, and for many people they can be severe enough to interfere with daily activities and the ability to live independently. But there is mounting evidence that the risk of developing such problems is strongly correlated with common health and lifestyle issues.
Age and Aging journal recently published a large cohort study by researchers at Kings College London, looking specifically at the relationship between cardiovascular risk factors and cognitive decline. Such risk factors – including obesity, smoking, blood pressure and cholesterol levels – have often before been proposed as significant. It matters, because these factors are usually modifiable: if detected early enough, we may be able to do something about them and prevent the damage. However, until now, there were no large-scale, long-term population-based studies to confirm or disprove the hypotheses. It was this gap that the current study aimed to address.
The study analysed data mostly collected between 2004 and 2005, and many participants also took part in follow-up studies several years later. This allowed researchers to track the progress of physical health and cognitive variables over time. Health professionals use a standard set of tests to measure memory and ‘executive function’, which involves verbal fluency, attention span and mental speed. These tests strangely resemble children’s games: how many animals can you name in one minute? How many of these ten words can you recall? Nonetheless they are widely accepted as reliable measures of cognitive functioning. In this study, the researchers used the results to calculate a cognitive index for each participant, based on a composite of their scores in each study, and how those scores deviate from the average.
The results confirmed the suspicion that the same risk factors that predispose a person to have cardiovascular health problems – stroke and coronary heart disease – also put them at risk of impaired cognitive function. Smoking emerged as a particular risk, being strongly and consistently associated with loss of memory and executive processing abilities at both the four year and eight year follow-up studies.
Interestingly, even borderline-high blood pressure appeared to be correlated with loss of memory function. In fact, this appeared to be a bigger risk factor than very high blood pressure: possibly because the borderline cases were less likely to have been considered worth treating with pressure-reducing antihypertensive drugs. This new finding points to a possible benefit of treating even the borderline cases. The good news is that the damage appears to take place slowly over several years, giving hope that early intervention may be able to successfully prevent it.
The researchers recommend using these findings in the design of future clinical trials to study attempts at preventative measures, eventually leading to population-based interventions. It is becoming increasingly clear, however, that there are many factors contributing to cognitive decline, and any successful intervention will have to take this into account and address the multiple causes.
