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Slowing Down Alzheimer’s Disease

Publié le 1 septembre, 2007 | Pas de commentaires
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Technological and medical advancements have led to a steady increase in the life expectancy and in the size of the older adult population. Consequently, the number of age-related ailments, such as Alzheimer’s disease, is on the rise. In addition to the emotional and psychological struggle experienced by patients and their families, Alzheimer’s disease poses a financial burden to health care systems worldwide. However, recent studies suggest that simple activities that stimulate the brain can prevent or delay the onset of dementia in individuals at risk.


Alexandre Duret-Lutz, , 2006
Certains droits réservés.

Due to advances in medical technology, life expectancy is increasing. With the parallel decline or stagnation in birth rates, the senior population is growing steadily. Recent estimates predict a doubling in size of this age group worldwide from 11 percent of the population in 2005 to 22 percent in 2050 (1). In more developed countries such as those in Western Europe and North America, it is estimated that by 2030, between a quarter and a third of the population will be aged 65 years or older (2; 3). Medical progress only prolongs physical, not mental, functioning. For that reason the body often outlives the mind and age-related neurological diseases such as dementia become more prevalent, which has a tremendous impact on healthcare systems. The annual global costs for the treatment of dementia are estimated to be around $315 billion, three quarters of which is spent in industrialized countries (4). How are we to combat the rise of neurological conditions such as Alzheimer’s disease?

Playing Checkers to Prevent Dementia

A recent paper by Wilson and colleagues (5) explores a potential means to help prevent or delay the development of AD. Wilson and colleagues followed a group of over 700 older adults and assessed the participants’ past and current cognitive activity and function annually for five consecutive years. Participants were asked how often they engaged in particular activities (e.g. reading or playing chess) and their cognitive function was assessed for memory, speed of processing, and visuospatial abilities. Of the 700 participants, approximately 13 percent developed AD and those who were cognitively inactive during the five years of assessment were 2.6 times more likely to develop AD than those who were considered to be cognitively active. This effect remained even after the researchers accounted for other factors such as socioeconomic status, frequency of social and physical activities, and past cognitive activity. In other words, being involved in tasks that require thinking and problem solving—such as reading the newspaper, playing checkers or chess, or visiting the library, seems to reduce the risk of developing AD. One might argue that low cognitive engagement is an early sign of AD rather than a prerequisite for its development. To address this question, Wilson and colleagues examined brain samples of deceased participants and found no association between the extent of neuropathological markers of AD (such as Lewy bodies, amyloid plaques, neurofibrillary tangles, and cerebral infarction) and the level of cognitive activity at baseline (i.e., at the beginning of the study). This suggests that a low level of daily cognitive involvement should be considered a risk factor for developing AD rather than an early sign of it. Therefore, actively engaging your mind regularly could help prevent, or at least delay, the onset of AD.

However, these findings must be interpreted with caution because of two major drawbacks to the study. First, past cognitive activity was measured retrospectively using self-reports, which are often biased and skewed. Self-reports of cognitive activity up to 40 years ago are more like estimates rather than exact measures. Second, the participants were followed only for three years on average (i.e. some of the participants dropped out before the 5th annual assessment), which is a relatively short period of assessment for research of this nature. Future studies should observe the cohort for a longer period of time to better assess the association between the frequency of cognitive activity and the likelihood of developing AD.

Memory Training to Prevent AD in MCI Patients

At the conference for Theoretical and Experimental Neuropsychology (TENNET) in Montreal, Canada this past June, Sylvie Belleville, a psychology professor at l’Université de Montréal, presented findings that support the preventive role of cognitive activity for the onset of dementia.

Their study (6), in contrast to the one by Wilson and colleagues (5), restricted the nature and the amount of cognitive activity of the participants by enrolling them in a specifically designed memory training program. The sample consisted of a group of healthy older adults and a group of patients diagnosed with amnestic mild cognitive impairment (MCI), which most researchers consider a pre-stage to AD (6; 7) (Amnestic MCI patients suffer from memory deficits that do not interfere significantly with their daily functioning and independence. However, 20-50 percent of MCI patients of this subtype develop AD(7).)

In the study by Belleville and colleagues (6), one group of participants — half of which were diagnosed with amnestic MCI and half which were cognitively healthy controls — received a memory training intervention for a total of 16 hours, while the remaining participants were put on a waiting list and served as a no-intervention control group. The training focused on episodic memory (i.e. memory of personal events) tasks such as face-name associations or learning and recalling words from a list. The findings showed that both healthy older adults and MCI patients benefited from the intervention, which resulted in an increased performance in episodic memory. Interestingly, some of the MCI patients even improved their episodic memory skills to the level of the healthy adults who did not receive any training. Participants assigned to the waiting list group showed no significant changes in episodic memory skills, suggesting that the cognitive training accounted for their improvement. In addition, the notable improvement in memory skills was accompanied by an increased sense of well-being.

These results are very promising but additional research is needed to replicate these findings and determine whether or not the proposed memory intervention program is reliable. An important aspect to keep in mind concerns the applicability of laboratory-based training to everyday memory functioning. The outcome measures were standardized memory tests and the extent to which the acquired mnemonic strategies are applied in daily life (e.g., remembering various errands) remains to be clarified. Furthermore, the participants were not followed for an extended period of time, meaning that long-term benefits associated with this training are yet to be determined.

Despite these caveats, the results indicate that early intervention strategies can improve the memory of individuals at risk of developing neurodegenerative diseases like AD and may prevent or delay their onset. Findings from both studies described here underline the importance of frequent cognitive activity in older age to counter the development of dementia and enhance quality of life. As our society grows older and continues to burden financially taxed healthcare systems, simple activities such as playing checkers or reading the paper may prove to be worth millions.

References

(1) United Nations Department of Economic and Social Affairs, Population Division. « Executive Summary on World Population Ageing 2007 ». 2007. Website. July 25th 2007. <http://www.un.org/esa/population/publications/WPA2007/wpp2007.htm>.
(2) Department of Health and Human Services, Center for Disease Control and Prevention « The State of Aging and Health in America 2007 Report ». 2007. Website. July 25th 2007. <http://www.cdc.gov/aging/saha.htm>.
(3) Statistics Canada, The Daily. « Population Projections ». 2005. Website. (December 15th 2005). July 25th 2007. <http://www.statcan.ca/daily/English/051215/d051215b.htm>.
(4) Alzheimer’s Association. « Worldwide Cost for Dementia Care Is $315 Billion Annually ». 2007. Website. (April 16th 2007). July 25th 2007. <http://www.alz.org/media_8491.asp>.
(5) Wilson, R.S., et al. « The Relation of Cognitive Activity to Risk of Developing Alzheimer’s Disease. » Neurology 69 (2007): 1-10.
(6) Belleville, Sylvie, et al. « Improvement of Episodic Memory in Persons with Mild Cognitive Impairment and Healthy Older Adults: Evidence from a Cognitive Intervention Program. » Dementia And Geriatric Cognitive Disorders 22 (2006): 486-99.
(7) Petersen, Ronald C., et al. « Mild Cognitive Impairment. » Archives of Neurology 56 (1999): 303-08.

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