Exercise as it relates to Disease/Physical activity at mid-life, and dementia risk decades later

This is a critic of an exercise and how it relates to dementia paper. This critic has been written as a university assignment for the University of Canberra for the unit: Health, Disease and Exercise.

The paper: Andel R, Crowe M, Pedersen N, Fratiglioni L, Johansson B, Gatz M. Physical Exercise at Midline and Risk of Dementia Three Decades Later: Population-Based Study of Swedish Twins. Journal of Gerontology. 2008; 61(1): p. 62-66.



What Is The Background To This Research?
Dementia is becoming more prevalent in todays society than ever and is thought to be linked with genetic, lifestyle, age and socioeconomic factors.

What is Dementia

Dementia is a blanket term used to describe a range of cognitive diseases and disorders that affects cognitive and behavioral functions. It appears to be progressive as it doesn’t happen overnight but progressively worsens over a period of time. There are several stages of mild cognitive disorders, with the worst being known as dementia.

Physical interventions have become the new hot topic in research in regards to interventions for dementia. Some journals boast of the physical interventions effects like:
 * Increased blood flow to the brain
 * Provides a ‘protection’ against the future risk of dementia
 * Healthier brains
 * Alternative to medicinal interventions
 * Reduced risk of falls in elderly
 * Reduced risk of other chronic diseases
 * Improved mental capacity and cognition

The purpose of this study was to determine if there was a correlation between any of the aforementioned factors and the onset of dementia.

Where Is The Research From?
This study was conducted using twin data extracted from the Swedish Twin Registry (STR). The study was conducted via a variety of universities listed below;


 * School of Aging Studies and Florida Alzheimer’s Disease Center, University of South Florida, Tampa.
 * Department of Psychology, University of Alabama at Birmingham.
 * Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
 * Department of Psychology, University of Southern California, Los Angeles.
 * Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
 * Department of Psychology, Go ̈teborg University, Sweden.

What Kind Of Research Was This?
This study was a case control study and co-twin control analyses. Case control studies are retrospective and aim to observe and measure a population with a specific illness or disease (Case) and then compare them with populations without the disease (Control).

[[File:Alzheimer and other dementias world map - DALY - WHO2004.svg|thumb|Alzheimer and other dementias world map

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What Did The Research Involve?
This research involved drawing participants from the Swedish Twin Register. The researchers then issued the participants with a self assessed questionnaire through which the participants were screened. Additionally; twins who were identified as having poor cognitive ability via a telephone call were brought in to a clinical setting for further identification of dementia.

What Were The Basic Results?
The results indicated that most participants engaged in light exercise. Interestingly, it was identified in the study that participants were mostly female (61%), largely drink alcohol (70%), and ate minimal fruit and vegetables (21%). Most surprisingly the majority of participants were under a BMI (Body mass index) of 25 kg/m2, only 11% of participants were above a BMI of 25.

Furthermore, out of 3134 participants, 264 participants obtained dementia following their original screening. Another characteristic worth mentioning is education, of the population only 37% had an education above a basic level, whereas in the group who ended up with dementia only 25% had an education level higher than basic.

There were some limitations with this study with the most glaringly obvious being the self assessment of physical activity, where it has been shown in various other papers that those who self report have a tendency to report in a better light than what is reality; i.e. participants saying they do regular exercise when they may do little to none. Some other limitations were; researchers were unable to test biological mechanisms, limited sample size, the study is nearly 10 years old, the researchers specified that more specifics are needed in regard to what exercise was undertaken. The research also indicates that exercise plays a serious role in reducing the onset of dementia, with regular exercise having the best affect followed in order of least likelihood of onset to most likelihood of onset; light, hard, and hardly any

How Did The Researchers Interpret The Results?
The researchers determined that light exercise and regular exercise was associated with a reduced chance of dementia and Alzheimer’s disease. In particular, there was a noticeably high correlation with regular exercise and a reduced chance. Interestingly, there was a low correlation with hard physical exercise and reduced chances of dementia and Alzheimer’s. Moreover, the researchers interpreted the data to conclude that a twin who engaged in more exercise and physical activity had a reduced chance of dementia between the twins, comparatively.

The researchers found that engaging in light or regular exercise reduced the chance of dementia and Alzheimer’s disease approximately 31 years later.

What Conclusions Should Be Taken Away From This Research?
This research was undertaken early in terms of the dementia research spotlight. What was significant at the time was that their follow up was greater than 31 years. Due to this research coming out early on in the Dementia research spotlight, it was still unclear how exercise interventions helped, although they concluded exercise helped it didn’t specify how it helped. More recent research has found specific benefits with certain types of training and are starting to understand the physiological responses.

The researchers indicated further research would be needed to find a suitable strategy to delay dementia.



What Are The Implications Of This Research?
This research has shown exercise interventions appear to be beneficial in delaying the onset of dementia. However further research needs to be conducted to understand physiologically how this is of benefit and how to best implement strategies to reduce the onset of dementia.