Tuesday August 4 2009
“Performing a mental exercise twice a day could help delay the rapid memory loss associated with dementia for more than a year,” The Daily Telegraph reported. It said that a study of nearly 500 people aged 75 to 85 years looked at how often they did crosswords or puzzles, read, wrote or played card games. Of those who developed dementia, people who did 11 mental exercises a week developed memory problems about a year and four months later on average than those who did four exercises a week.
This study suggests that elderly people who will go on to develop dementia may delay their onset of rapid mental decline by taking part in mentally stimulating activities. However, the age at which people were diagnosed with dementia was not affected.
The study has some limitations, including the fact that it was a relatively small study and only measured participation in the activities at one point in time. Although this study alone does not prove that increased mental activity reduces risk of dementia, keeping mentally and physically active is probably beneficial for people of all ages.
Where did the story come from?
The research was carried out by Dr Charles B Hall and colleagues from Albert Einstein College of Medicine and other research centres in New York. The study was funded by the National Institute on Aging and the National Institute of Neurological Disorders and Stroke. It was published in the peer-reviewed medical journal Neurology.
What kind of scientific study was this?
This was an analysis of data collected in a cohort study called the Bronx Aging Study (BAS). The analysis aimed to investigate whether mentally stimulating leisure activities can affect memory decline in people who develop dementia. The researchers had shown in previous studies that early life education delayed the onset of memory decline in people who develop dementia, and they thought that taking part in mentally stimulating leisure activities might explain this link.
Between 1980 and 1983, 488 healthy adults aged between 75 and 85 years and living in the community in the Bronx were recruited for the study. Over half (64.5%) of the participants were women and 90% were white. The researchers excluded anyone who already had dementia or had Parkinson’s disease, liver disease, alcoholism, a terminal illness, or severe hearing or visual impairment that prevented them from completing the cognitive tests that were part of the study.
At the start of the study the participants filled in questionnaires about themselves, including their level of education. They were also asked how often they participated in six mentally stimulating leisure time activities: crosswords, reading, writing, board or card games, group discussions or playing music. The activities were graded by the Cognitive Activity Scale (CAS) scoring system, which gave seven points for each activity they took part in daily, four points for each activity they took part in several days a week, one point for each activity they took part in once a week and zero points for taking part never or rarely. Each participant’s scores were added up for all six activities to give an overall CAS score.
The participants completed an extensive set of cognitive and psychological tests at the start of the study and at subsequent visits every 12 to 18 months. These were used as part of the process of diagnosing dementia. The tests also included a word list memory test (the Buschke Selective Reminding Test, or SRT) that was not used as part of the diagnostic process.
Participants who were suspected of developing dementia had a clinical examination including a CT scan and blood tests to rule out conditions that might cause reversible dementia. Diagnoses of dementia were decided on through discussions between the study experts (a neurologist, neuropsychologist and a geriatric nurse clinician). The experts reviewed all collected information and used standard criteria (called DSM-III and DSM-III-R criteria) to make their diagnoses. Participants were followed up until they died or were lost to follow up.
The current analysis included only people who provided information about their education and leisure activities and who were cognitively normal at the start of the study, but went on to develop dementia. Using statistical modelling, the researchers looked at whether participants’ leisure mental activities (CAS score) were related to how their memory (SRT score) changed over time, and to how long it took for them to be diagnosed with dementia. The model that was used assumed that memory declines at a constant rate to a certain point, at which decline becomes more rapid.
What were the results of the study?
The 101 people who developed dementia were on average 79.5 years old at the start of the study, and were followed up for an average of five years before being diagnosed with the condition. About half of these scored seven or less on the Cognitive Activity Scale (the equivalent of one mentally stimulating activity a day on average).
The researchers found that participation in mentally stimulating leisure activities was not associated with the age at which dementia was diagnosed.
However, the activities did have an effect on when accelerated memory decline began. Each extra activity day a week delayed the onset of accelerated memory decline by 0.18 years (about two months). This meant that for people who took part in 11 activities per week accelerated memory decline set in about 1.3 years (one year and four months) after those who took part in only four.
However, once this accelerated memory decline had begun, having participated in more mentally stimulating activities at the start of the study was associated with an increased rate of memory decline. Each additional activity day increased the decline of memory by 0.14 SRT points a year. The researchers reported that their model also indicated that those who took part in more mentally stimulating activities at the start of the study had slightly lower SRT scores when they were diagnosed with dementia, but this difference was not statistically significant.
These results remained significant after taking early life education into account.
What interpretations did the researchers draw from these results?
The researchers conclude that engaging in mentally stimulating leisure activities delayed the onset of rapid memory decline in people who develop dementia. This effect was independent of a person’s level of education.
They say that their results suggest that taking part in mentally stimulating leisure activities may maintain mental “vitality”, and that studies investigating whether increasing participation in such activities could delay or prevent dementia are needed.
What does the NHS Knowledge Service make of this study?
This study suggests that the onset of rapid mental decline in elderly people who go on to develop dementia may be delayed by participation in mentally stimulating leisure activities. However, it does not show whether taking part in these activities affects the risk of developing dementia. Also, having participated in more mental activities did not affect the age at which people were diagnosed with dementia, and once memory decline had started was associated with a faster rate of memory decline.
As the researchers suggest, future prospective intervention studies specifically designed to look at whether mental activities can prevent or delay dementia are needed. This study sets the scene for such research, but there are several points to note that mean its results cannot be considered to be conclusive:
- The participants reported their participation in mentally stimulating activities at only one point in time. Their answers may not reflect their participation in such activities during their lifetime before or after study enrolment. It is possible that those people whose memories had already started to decline as part of a process leading to dementia when they filled out the questionnaire may no longer have enjoyed mentally stimulating activities and, therefore, participated less.
- The mentally stimulating activities assessed were pooled together, meaning that the effects of each activity cannot be determined. The researchers suggest that some activities may have greater effects than others.
- The study was relatively small, with only 101 people developing dementia. A larger study, preferably a controlled trial, would provide results that are more robust.
- It is possible that the differences between the more and less mentally active groups are caused by imbalances between the groups other than their mental activity. Other than education, this study did not look at the effects of other factors that could potentially affect risk of developing dementia, therefore this possibility cannot be ruled out.
- The study was performed in the US, and the majority of participants were white. As such, the results may not apply to people living in different countries or from different ethnic groups.
Although this study by itself does not prove that increased mental activity reduces the risk of dementia, keeping mentally as well as physically active seems likely to provide benefits for people of all ages.