Activity and cognitive functioning 1 Factors affecting cognitive capacity

Persons with high functional reserve may have increased capacity to keep learning and adapting despite age-related changes. This view has been developed in more functional terms by Stern (2002) and Scarmeas and Stern (2003) with the concept of “cognitive reserve”. For Scarmeas and Stern (2003), cognitive reserve related back to the fact that innate intelligence or aspects of life experience like educational or occupational attainments provide a reserve, in the form of a set of skills or repertoires that allows some people to prevent cognitive decline associated with normal aging or Alzheimer’s disease.

Recent researches tried to identify parameters contributing to the development of cognitive functions. Education is largely recognized as having an impact on cognitive functioning, and is thought to support the cognitive reserve capacity (e.g. Le Carret et al., 2003). Some studies confirming this idea have suggested that people with a high educational level have lower risk of developing dementia compared to people with a low educational level (Letenneur et al., 1999). But several studies have also suggested that differential susceptibility to age-related cognitive decline or to Alzheimer’s disease is related to variables, such as: occupation, professional or leisure activities, and life style (Fillit et al., 2002; Fratiglioni et al., 2004). All these findings on cognitive reserve may have important implications for the structure of retirement in old age. Keeping occupational activities as far as possible may contribute to maintain cognitive functioning in old age, preventing in this way, at least partially, some forms of dependency related with diminishing autonomy.

In SHARE, cognitive functioning was measured using short and simple tests of orientation, memory (learning and recall of a list of ten words), verbal fluency (a test of executive functioning) and numeracy (arithmetical calculations). Adam et al. (2007) decided to compute a global measure of cognitive functioning by focusing on two key cognitive domains: episodic memory (with the word list recall task) and executive functioning (with the semantic fluency task). It is widely recognized that episodic memory and executive functioning are two cognitive domains that are particularly sensitive to cognitive aging.

The memory task integrated in the survey was a test of verbal learning and recall, where the participants were required to learn a list of ten common words. The memory score was calculated by adding the number of words recalled at the immediate and delayed recall phases (score ranging from 0 to 20). Executive functioning was assessed using a fluency task, which is a test of how quickly participants can think of words from a particular category; in this case, they had to name as many different animals as possible in one minute. The global assessment score is computed by averaging the standardized memory and fluency scores. It is assumed to represent a more global and more sensitive assessment of cognitive functioning.

The SHARE data indicate that cognitive functions decline systematically with age, e. g. the memory test varies from 9.9 to 6.0 words in average from 50-54 to 80-84 years old categories, as well as it increases systematically with years of education.

Adam et al.(2007) using a frontier approach find that, all other things being unchanged, for an average individual aged 60 and having study 10 years, one year more of education “compensates” 4 years of cognitive ageing.

In a recent meta-analysis including studies conducted from 1966 through 2001, Colcombe and Kramer (2003) showed that, aggregating across studies, fitness training has a positive effect on the cognitive functions of older people, and thus on the development and maintenance of a cognitive reserve. Finally, S. Adam et al. (2007) show that living alone have a negative impact on the preservation of cognitive reserve; a result that is consistent with studies showing that social isolation or social disengagement is a risk factor for cognitive impairment among elderly persons (Fratiglioni et al., 2004).

In a second step the SFA model used by Adam et al. (2001) show, for a 60-year-old individual, the positive impact on cognitive functioning of variables directly associated with the notion of activities. For instance, a 60-year-old individual is expected to delay his/her cognitive aging by 1.03 to 1.30 years (depending of the model) if she/he continues to work instead of retiring, all other things been equal, and 3.23 to 4.08 years if she/he performs at least one non-professional activity.

The analysis also shows that the impact of physical activities varies as a function of frequency of these activities. Thus, the estimated benefit in terms of years of cognitive aging for a 60-year-old individual changes: (1) from 2.61 to 3.30 years when physical activities are performed more than once a week instead of never or rather never ; and, even more strikingly, (2) from 3.46 to 4.41 years in the case of moderate physical activities. The involvements of the two other variables representing mobility limitations or single-person household indicate effects lesser than one year of cognitive performance cost.

Globally, these results confirm similar observations, such as Menec, 2003, that show in a six-year longitudinal study a relation between everyday activities and successful aging. Or as Schooler et al. (1999) who showed that the level of complexity of an occupation positively influences the level of intellectual functioning. The protective effect of professional activities on cognitive aging should be all the greater the more these activities tend to mobilize cognitive resources.

Moreover, the analyses show that these positive effects are slightly greater for non-professional activities compared to professional activities. So a 60-year-old individual who continues to work delays his/her cognitive aging by at least 1.03 years, while this individual delays cognitive aging by 3.23 years if he/she performs one non-professional activity. This superiority can be explained by the fact that non-professional occupational activities are mostly voluntary while professional activity are imposed for some people, and this constraint may generate depression and anxiety (factors that have negative effects on cognitive functioning). Some studies show that retirement can lead to a reduction in depressive symptomatology (e.g. Gallet al., 1997).

2.2.2 Activity and cognitive performance in Europe

The simultaneous interdisciplinary, international and longitudinal nature of the English Longitudinal Study on Ageing (ELSA) and the Survey on Health, Ageing and Retirement in Europe (SHARE), constitutes a living laboratory to identify the impact of institutions on labour force participation among the population aged 50 and more (Börsch-Supan et al., 2005).

Figure 1 illustrates what must be considered as a starting point in this research field. On the horizontal axis are reported the percentage points slowdown in employment rates when we compare the 50-54 to the 60-64 years old groups in HRS, ELSA and SHARE countries and, on the vertical axis, the slowdown in cognitive performances, a ten-words two-recall memory test, between the same age groups within the same countries. This figure highlights the potential unexpected consequences of early retirement programs on cognitive performances. Without anticipating the results of detailed statistical studies that would address, among others, the potential bidirectional causality between cognitive impairment and retirement, it appears that countries that performed better in terms of labour market participation among the elderly, also seem to have better prevented cognitive capacity decline and, as it is now well documented for the effect of educational skills, better prevented the early development of Alzheimer deceases.

Figure I.5: Employment rate and cognitive performance. Relative difference between 60-64 and 50-54 years old men

United States Denmark Greece Sw eden Sw itzerland United Kingdom Spain Germany Italy The Netherlands Belgium Austria France -25% -20% -15% -10% -5% 0% -100% -90% -80% -70% -60% -50% -40% -30% -20% -10% 0%

Employment rate (relative difference)

C ogni tiv e per fo rm anc e ( re la tiv e di ffer enc e)

Source: Own calculations using ELSA, HRS and SHARE data

Globally, the results show a relation between everyday activities and successful aging, even if the data did not allow them to distinguish between cognitively stimulating (or non-stimulating) professional or occupational activities. However, in light of studies showing that the level of complexity of an occupation positively influences the level of intellectual functioning (e.g., Schooler et al., 1999, for professional activities; Hultsch et al., 1999, for social and new-information-processing activities), the protective effect of professional activities on cognitive aging should be all the greater the more these activities tend to mobilize cognitive resources.

Although these results clearly confirm the relationship between activity and cognitive functioning, the important and thorny problem of the “causal relation,” which is not always addressed in studies, remains to be considered. Indeed, the question is whether the decrease in cognitive functioning is the consequence of the reduction in activity or vice versa. As suggested by Schooler and Mulatu (2001), there is probably a reciprocal relation between cognitive functioning and cognitive stimulation.

Physical activity seems to be a strong predictor of successful ageing. In 2002, The World Health Organisation (WHO) reported that physical inactivity was estimated to cause 3-4% of the disease burden. Lack of physical activity, reduces notably the number of falls, reduces blood pressure and promotes mental health and social activity. WHO considers that, in order to benefit health, individuals should participate in at least 30 minutes of moderate intensity activity per five or more days a week but even intermittent daily activity of moderate intensity benefits health.

2.2.3 Overview by policy instrument

Preserving the cognitive capacity of elderly people is an essential component to ensuring they enjoy an independent and active life. Autonomy and competence in old age is essential and activation of cognitive functions is desirable. The combination of memory training and exercise seems to be a guarantee for healthy and satisfactory ageing and furthermore, assures sustainability.

Surveys show that dependency increases with age and participating in community and social life will constitute an important aspect of limitations faced by older people. The increase is expected to be more significant among the very old persons.

The literature about cognitive reserve (DIK, M. et al.) give us proofs of the efficiency of all kind of activity on the cognitive reserve preservation. Physical activity has shown to be inversely associated with cognitive decline in older people. Findings suggest a positive association between regular physical activity early in life and level of information processing speed at older age in men, not women. These findings suggest that early life physical activity may delay late-life cognitive deficits. This may supports prevention policy programs.

Physical inactivity increases with age and particularly among individuals aged over 65. Evidence support the need for older people to exercise, even when starting late in life. Public interventions to promote physical activity among older people have proven to be cost-effective in terms of additional years lived in good health.

Higher levels of cognitive activity and educational attainment are associated with higher level of cognition, reduced cognitive decline, and reduced risk of dementia in old age. Cognitive activity and education seems to bolster the brain’s ability tolerate age-related neuropathology. Literature about cognitive reserve (Wilson R. et al.) found that retrospective estimates of level of cognitive activity across he life span were robustly related to late life cognitive activity. Thus cognitive activity in early life, along with early life socio-economic conditions appear to affect late life cognitive function in part by affecting cognitive lifestyle activities throughout adulthood and old age. Just like for physical activity, for education and intellectual activity is very important along the life/.To avoid early cognitive decline, prevention by childhood and adulthood education is the best solution according to the cognitive reserve literature.

In the coming decades, the WHO expects depression in industrialised countries to develop into a number one public illness. Because of the nature of the symptoms and the fact that many older people live alone, mental illness in older people could be largely under detected. Furthermore, mental health problems may be perceived by older people and their families, as well as by professionals, as an inevitable consequence of ageing, and not as a health problem, which requires action.

Older people represent a high-risk group and depression along with dementia is under diagnosed among them, since symptoms are often mistaken for the process of ageing. Mild cognitive impairment converts to dementia in laps of time of 3 to 4 years. Some of the predictors of these disorders are chronic illness, isolation and dependency. Preventive home visits offer the possibility to reach out to and to detect older people suffering from related psychological and mental disorders.

WHO considers that active ageing is the process of optimizing opportunities for health, participation and security in order to enhance quality of life as people age. Active ageing applies to both individuals and population groups. It allows people to realize their potential for physical, social, and mental well being throughout the life course and to participate in society according to their needs, desires and capacities, while providing them with adequate protection, security and care when they require assistance. The word “active” refers to continuing participation in social, economic, cultural, spiritual and civic affairs, not just the ability to be physically active or to participate in the labour force.