Elsevier

Archives of Gerontology and Geriatrics

Volume 45, Issue 3, November–December 2007, Pages 307-318
Archives of Gerontology and Geriatrics

Influence of level of activity on cognitive performance and cognitive plasticity in elderly persons

https://doi.org/10.1016/j.archger.2007.01.061Get rights and content

Abstract

As a result of the rapid increase in the elderly population over recent decades, the analysis of factors influencing cognitive aging has become a focus of great interest for current research. In this area, numerous papers have indicated a relation between specific psychosocial variables and the level of activity and cognitive performance and plasticity in old age. This study aimed at testing a theoretical model, which establishes relations between level of activity, cognitive performance and cognitive plasticity in old age. In this study 176 elderly persons participated and were evaluated by means of a cognitive screening test, two cognitive plasticity evaluation tests and a questionnaire on the level of activity before and after retirement. A structural equation analysis was carried out on the data, which reveal significant relations between level of activity after retirement and cognitive performance and plasticity. Similarly, a significant relation is established between cognitive functioning and plasticity. The findings lend support to studies affirming that a high level of activity protects against cognitive decline and is related to cognitive plasticity in old age.

Introduction

As a result of the rapid increase in the elderly population over the recent decades, the analysis of factors which influence cognitive aging has become a focus of great interest for current research. The importance of this area is largely due to the fact that, although old age is associated with a higher probability of cognitive functioning decline, this decline does not appear in a uniform fashion. On the contrary, considerable individual differences in patterns of change and maintenance have been demonstrated (Baltes et al., 1984, Schaie, 1990, Willis, 1990, Christensen et al., 1994). Thus, while some individuals present decline, others continue to maintain high levels of cognitive functioning in spite of the passing of the years.

When analyzing this interpersonal variability in later life development, a basic distinction is made between present performance (observable intellectual repertoire and/or execution that a person may demonstrate in a specific situation) and potential performance (level of performance that a person may demonstrate if alternative conditions to optimize execution are considered or introduced). The existence of this modifiability has been termed “cognitive plasticity” by Baltes and Willis (1982), who defined the concept as intellectual performance in old age under optimizing conditions, which do not normally exist in the day-to-day life of the person.

In order to evaluate this modifiability, Baltes et al. (1984) developed a procedure for “testing the limits” which follows the traditional format of test–train–test used in evaluating learning potential. The procedure consists of the repeated application of a traditional test with an intermediate phase of one or more training sessions directed at the task concerned. Two subject measurements are obtained from this procedure, the pretest or execution baseline and the posttest  pretest difference. This difference, denominated “reserve capacity” or “plasticity” by Baltes et al. (1984), indicates the extent to which a subject could be improved after a systematic training (Calero et al., 2000a). In various research studies, this construct has been related to cognitive deterioration and/or decline in the elderly person (Baltes and Raykov, 1996, Calero and Navarro, 2004, Fernández-Ballesteros et al., 2005).

With regard to the factors associated with variability in patterns of cognitive aging, we can find studies referred mainly to biological or genetic factors (Katzman, 1993, Lee, 2003), and studies referred mainly to environmental and lifestyle factors. If we center on environmental and psychosocial aspects, as it is appropriate, given the topic of this study, we find that numerous papers have indicated between specific psychosocial variables and the level of activity and cognitive performance a relation and plasticity in old age. These include both cross-sectional studies (e.g., Christensen et al., 1995, Newsom and Schulz, 1996) and longitudinal studies (e.g., Unger et al., 1999, Menec, 2003, Hooren et al., 2005). The following paragraphs offer a summarized description of studies from the two research approaches.

With regard to cross-sectional studies demonstrating the relation between level of activity and cognitive performance, research by Christensen et al. (1995) analyzed the influence of the level of activity in day-to-day life on cognitive performance. The study found that the level of activity of the person not only influences cognitive performance but accounts for a greater proportion of variation in cognitive functioning than other variables such as gender, sensorial functioning, physical health and level of education. Similarly, a study by Newsom and Schulz (1996) found that cognitive deterioration is associated with a lower level of social contacts, both in family and with friends, and a lower level of perceived social support.

As regards the longitudinal studies, Seeman et al. (2001) also analyzed the relation between social relations and support and the pattern of cognitive aging as a part of their MacArthur research program on successful aging. The results of this study indicated that greater emotional support and higher frequency of social relations are factors associated with better cognitive functioning. The relation between lifestyle and the risk of suffering cognitive decline or dementia has also been demonstrated by Scarmeas et al. (2001). This study involved a 7-year follow-up of an initial sample of 1772 elderly people over 65 without dementia. Again, subjects with a high level of activity had a significantly lower risk of developing dementia compared with subjects in the low activity group. Specifically, the study indicates that the types of activities most clearly associated with lower risk of dementia are social, physical and intellectual, and of these, physical and intellectual activities are most relevant.

Turning to studies relating the level of activity with cognitive plasticity, longitudinal research by Hultsch et al. (1999) centered on the cognitive functioning of a large sample of subjects with an evaluation period of 6 years, and established a relation between lifestyle and change in cognitive functioning. Thus, participants who undertook new activities involving a certain level of mental stimulation presented less probability of suffering decline during the follow-up. These results are congruent with the hypothesis that participation in activities contributes to maintain, and even increase, the level of cognitive functioning, in line with the “use it or lose it” hypothesis defended by the authors of the study.

A further longitudinal study by Bassuk et al. (1999) examined the relation between cognitive functioning and social relations in a large sample of elderly people over a period of 12 years. Again, the authors found that a higher base level of social relations, defined as having more contacts with friends and family, and a higher level of participation in group activities had a protective effect against cognitive decline.

More recently, Menec (2003) also demonstrated the relation between successful aging and day-to-day activities. The results of this large-sample study indicate that level of activity is negatively related to cognitive and physical functioning, in the sense that subjects who demonstrated a lower level of activity in the first phase of the research presented a more pronounced decline during the follow-up. Similarly, a higher level of activity was associated with stronger feelings of well being, lesser cognitive and functional decline and a reduced risk of mortality.

To sum up, the studies reviewed seem to demonstrate that on the one hand, maintaining an active lifestyle in old age at the physical, mental and social levels may protect against cognitive decline, and also that these same variables are related to cognitive plasticity. Given these findings, it seems appropriate to inquire about the mechanisms by which this effect is produced. Although various hypotheses have been proposed (see for a review: Scarmeas and Stern, 2003), it is of particular interest here the hypothesis that a high level of activity in day-to-day life increases the cognitive plasticity of the person by demanding a greater and more efficient communicative capacity and the activation of more cognitive resources and capacities (Carnero-Pardo, 2000, Fratiglioni et al., 2000).

On the basis of our review of the literature, we developed a theoretical model which aims to establish the relations between level of activity, cognitive performance and cognitive plasticity. The following paragraph offers a summarized description of the model, which we tested during the course of the present investigation.

While a high level of activity throughout the life of a person is related to the level of cognitive execution presented in old age, it is the level of activity maintained by the person during old age which is related to cognitive plasticity, in such a way that this plasticity may be influenced both by the level of cognitive functioning and by the level of activity. At the same time, the plasticity also plays a protective role (of maintenance) with regard to cognitive functioning.

Section snippets

Subjects

A total of 176 elderly persons participated in the study. Age of participants was between 60 and 98 years (mean age 75.8 ± 8.4, S.D.). Female/male ratio was 65.3/34.7%. With respect to level of education, 41.2% had no formal education while 58.8% had received some sort of academic training, mostly primary studies (33.7%) or secondary studies (19.4%); 75% of participants lived in residences for elderly people, and 25% lived in their own homes.

Cognitive performance test

We applied the “Mini-Examen Cognoscitivo” (MEC) (Lobo

Results

Although there are variables such as age and educational level that have demonstrated a positive relation with cognitive status and cognitive plasticity, those have not been the objective of this study. We shall start by presenting descriptive data of the mean scores obtained in the tests and the different variables in the questionnaire (Table 1). In general, it may be said that the mean score for the MEC test and for the gain scores in the two learning potential tests indicate that the sample

Discussion

Our principal interest in undertaking this research was to determine the extent to which certain lifestyle variables may determine the presence of a good level of cognitive performance and cognitive plasticity in old age. In this respect, we started with the premise that a high level of activity could counterbalance the negative effects of aging by activating cognitive abilities which may otherwise deteriorate due to lack of practice. This premise was based on the considerable number of studies

Conclusions

In general, all the findings described above may be viewed as confirmation of the data in the specialized literature concerning the relation between diverse psychological variables and cognitive status and plasticity, in which it is affirmed that an active physical, mental and social lifestyle protects against cognitive deterioration and is associated with plasticity (Christensen et al., 1995, Hultsch et al., 1999, Unger et al., 1999, Carnero-Pardo, 2000, Fratiglioni et al., 2000, Scarmeas et

Acknowledgements

The authors wish to extend special thanks to Frank Matthies (University of Osnabrück, Germany) for his great help with the statistical analysis. Our thanks also to Dr. Julian Bourne of the University of Granada for translating the original Spanish manuscript into English. This research has been financed by the Research Project “Variables psicológicas y psicosociales relacionadas con la plasticidad y el declive cognitivo en ancianos con deterioro cognitivo leve” (BSO 2002-01 561) of the Spanish

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