How ageing and social factors affect memory

Age and Ageing,  July, 1999  by Fred C.J. Stevens,  Charles D. Kaplan,  Rudolph W.H.M. Ponds,  Joseph P.M. Diederiks,  Jellemer Jolles

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Keywords: ageing, lifestyles, locus of control, metamemory, social factors

Introduction

Activity theory states that lifestyle activities are necessary for successful ageing [1, 2]. Conceptually, lifestyle consists of two components: `life conduct', expressed in personal choices, and `life chances', the opportunities available to realise these choices [3-5]. Cognitive functioning in old age may be facilitated by an active lifestyle. While many age differences in memory performance are attributed to intellectual activity and educational level, declining cognitive performance in old age may specifically relate to both cognitive style (e.g. attitudinal and motor-cognitive flexibility), specific lifestyle variables (e.g. the absence of an active lifestyle or a breakdown of family ties), socioeconomic status and social interaction. Contradictory demands and a diversity of stimuli seem to stimulate cognitive activity [6-10]. Active conduct in a demanding environment may help to maintain cognitive fitness throughout life [11-13].

Social network theory suggests that interactions with other people, mostly of the same status or age group and/or lifestyle, is beneficial [14, 15]. The social benefits may extend to cognitive performance. Active people may be better equipped to evaluate their cognitive functioning continuously. A good health and perceived internal locus of control may be beneficial to cognitive performance, although results are inconsistent [6, 8, 16-21]. In sum, three categories of variables are hypothesized to be related to cognitive performance: lifestyle, social network and locus of control. There are, however, few reports on different patterns of these variables across different components of self-rated components of memory abilities. We have studied the relationship of these variables to different components of metamemory (the self-knowledge and self-belief in one's own memory functioning [22, 23]). The instrument used here asks respondents to rate their memory capacity, change in memory functioning and related feelings of stress and anxiety.

Methods

The sample was derived from the second panel of the Maastricht Aging Study, a large-scale longitudinal study of cognitive ageing in relation to biological, medical and psychosocial factors [24]. The Maastricht Aging Study draws from a registration network of general practitioners in the Netherlands, containing demographic and health characteristics of more than 60 000 patients from 15 general practices and 42 practitioners. Subjects included in the register are representative of the south Netherlands population. Exclusion criteria are those medical conditions that may interfere with normal cognitive functioning [25].

The sample, stratified for age and sex, consisted of 497 persons aged between 25 and 82 (mean age 53 years). Two-hundred and fifty-two (51%) were women and 245 were men. Respondents were equally distributed among age categories (27% were aged 25-40, 25% were aged 41-55, 25% were aged 56-70 and 23% were aged 71-82). Level of education ranged from primary school (14%) to university (20%). Those included had no acute illnesses. Seventy-eight percent of the sample had a partner and 80% had children. Of those under 65 years, 62% had a full-time or part-time job [24].

To measure metamemory, the abridged version of the Metamemory in Adulthood (MIA) questionnaire was used [23, 26, 27]. The original instrument consists of seven subscales, three of which were used in this study: memory capacity, memory change and memory anxiety. Memory capacity ([Alpha] = 0.84) refers to a person's perceived memory functioning in daily life. The scale consists of 12 items, such as: `I am good at remembering names' (5 = agree strongly, 1 = disagree strongly) and `I am good at remembering birthdays'. Memory change ([Alpha] = 0.91) consists of 12 items, such as: `I can remember things as well as always' and `I'm less efficient at remembering things now than I used to be'. High scores indicate little memory change. Memory anxiety ([Alpha] = 0.88) refers to perceived feelings of stress and anxiety and consists of 12 items, such as: `I get upset when I cannot remember something' and `I find it harder to remember things when I am upset'.

For lifestyle conduct, two measures were used: sports activities and perceived activity. Sports activities were measured by asking respondents how many hours a week they usually spent on physical exercise (range 0-18h, mean 2). Perceived activity was measured by summing answers to two five-point scales: on whether they considered themselves to be active and how active they were in comparison to other people of the same age. The life chances component of lifestyle was determined by asking whether they participated in one or more voluntary organizations (clubs, social activities, music). Network characteristics were measured by asking: (i) how many friends and family members they could rely on for private matters (1 = nobody; 4 = 10 people and more) and (ii) how often they had had contact with one or more of these people in the last few months (1 = never; 5 = daily). Subjects were also asked whether they lived with a partner, had children, had a full-time or part-time paid job.