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Social involvement, behavioural risks and cognitive functioning among older people

Published online by Cambridge University Press:  14 December 2009

HENRIETTE ENGELHARDT ,
ISABELLA BUBER ,
VEGARD SKIRBEKK  and
ALEXIA PRSKAWETZ
HENRIETTE ENGELHARDT*
Affiliation:
Department of Population Studies, Otto Friedrich University, Bamberg, Germany.
ISABELLA BUBER
Affiliation:
Vienna Institute of Demography, Vienna, Austria.
VEGARD SKIRBEKK
Affiliation:
Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
ALEXIA PRSKAWETZ
Affiliation:
Vienna Institute of Demography, Vienna, Austria. Institute for Mathematical Methods in Economics, Vienna University of Technology, Vienna, Austria.
*
Address for correspondence: Henriette Engelhardt-Woelfler, Population Studies, Otto Friedrich University Bamberg, Lichtenhaidestr. 11, D-96045Bamberg, Germany E-mail: henriette.engelhardt-woelfler@uni-bamberg.de
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Abstract

This study analyses the relationships between cognitive performance, social participation and behavioural risks, taking into account age and educational attainment. We examine individual data for 11 European countries and Israel from the first wave of the Survey on Health, Ageing and Retirement in Europe (SHARE). The stochastic frontier approach methodology enables us to identify different sources of plasticity on cognitive functioning while taking into account age-related decline in cognitive performance. Several social participation variables were examined: employment status, attending educational courses, doing voluntary or charity work, providing help to family, friends or neighbours, participating in sports, social or other clubs, in a religious organisation and in a political or community organisation, and we controlled for age, education, income, physical activity, body-mass index, smoking and drinking. In the pooled sample, the results clearly show that all kinds of social involvement enhance cognitive functions, in particular in work. Moreover, behavioural risks such as physical inactivity, obesity, smoking or drinking were clearly detrimental to cognitive performance. Models for men and women were run separately. For both genders, all social involvement indicators associated with better cognitive performance. The results varied by countries, however, particularly the signs of the associations with a number of indicators of social involvement and behavioural risks.

Keywords

cognitive ageingcognitive reservesocial involvementbehavioural riskssocial engagement

Information

Type
Research Article
Information
Ageing & Society , Volume 30 , Issue 5 , July 2010 , pp. 779 - 809
Copyright
Copyright © Cambridge University Press 2009

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References

Adam, S., Bay, C., Bonsang, E., Germain, S. and Perelman, S. 2006. Occupational Activities and Cognitive Reserve: A Frontier Approach Applied to the Survey of Health, Ageing and Retirement in Europe (SHARE). Centre de Recherche en Économie Publique et de la Population [Research Centre on Public and Population Economics], Working Paper 0605, HEC-Management School, University of Liège, Belgium. Available online at http://ideas.repec.org/p/rpp/wpaper/0605.html [Accessed 26 August 2009].Google Scholar
Aigner, D., Lovell, K. and Schmidt, P. 1977. Formulation and estimation of stochastic frontier production function models. Journal of Econometrics, 6, 1, 21–37.CrossRefGoogle Scholar
Ball, K., Berch, D. B., Helmers, K. F., Jobe, J. B., Leveck, M. D., Marsiske, M., Morris, J. N., Rebok, G. W., Smith, D. M., Tennstedt, S. L., Unverzagt, F. W. and Willis, S. L. 2002. Effects of cognitive training interventions with older adults. Journal of the American Medical Association, 288, 18, 2271–81.CrossRefGoogle ScholarPubMed
Baltes, P. B. and Baltes, M. M. 1990. Psychological perspectives on successful aging: the model of selective optimization with compensation. In Baltes, P. B. and Baltes, M. M. (eds), Successful Aging: Perspectives from the Behavioral Sciences. Cambridge University Press, Cambridge, 1–34.CrossRefGoogle Scholar
Baltes, P. B. and Mayer, K. U. (eds)1999. The Berlin Aging Study: Aging from 70 to 100. Cambridge University Press, New York.Google Scholar
Bardage, C., Pluijm, S. M. F., Pedersen, N. L., Deeg, D. J. H., Jylhä, M., Noale, M., Blumstein, T. and Otero, A. 2005. Self-rated health among older adults: a cross-national comparison. European Journal of Ageing, 2, 2, 149–58.CrossRefGoogle ScholarPubMed
Barnes, L. L., Mendes de Leon, C. F., Wilson, R. S., Bienias, J. L. and Evans, D. A. 2004. Social resources and cognitive decline in a population of older African Americans and whites. Neurology, 63, 12, 2322–26.CrossRefGoogle Scholar
Bassuk, S., Glass, T. A. and Berkman, L. F. 1999. Social disengagement and incident cognitive decline in community-dwelling elderly persons. Annals of Internal Medicine, 131, 3, 165–73.CrossRefGoogle ScholarPubMed
Battese, G. E. and Coelli, T. J. 1995. A model for technical inefficiency effects in a stochastic frontier production function for panel data. Empirical Economics, 20, 2, 325–32.CrossRefGoogle Scholar
Beland, F., Zunzunegui, M.-V., Alvarado, B., Otero, A. and del Ser, T. 2005. Trajectories of cognitive decline and social relations. Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 60, 6, P320–30.CrossRefGoogle ScholarPubMed
Belgrave, L. L., Haug, M. R. and Gomez-Bellenge, F. X. 1987. Gender and race differences in effects of health and pension on retirement before 65. Comprehensive Gerontology B, 1, 3, 109–17.Google ScholarPubMed
Bennett, D. A., Wilson, R. S., Schneider, J. A., Evans, D. A., Mendes de Leon, C. F., Arnold, S. E., Barnes, L. L. and Bienias, J. L. 2003. Education modifies the relation of AD pathology to level of cognitive function in older persons. Neurology, 60, 12, 1909–15.CrossRefGoogle ScholarPubMed
Berkman, L. F., Glass, T., Brissette, I. and Seeman, T. E. 2000. From social integration to health: Durkheim in the new millennium. Social Science and Medicine, 51, 6, 843–57.CrossRefGoogle ScholarPubMed
Blum, J. E., Jarvik, L. F. and Clark, E. T. 1970. Rate of change on selective tests of intelligence: a twenty-year longitudinal study of aging. Journal of Gerontology, 25, 3, 171–6.CrossRefGoogle ScholarPubMed
Bond, G. E., Burr, R., McCurry, S. M., Borenstein Graves, A. and Larson, E. B. 2001. Alcohol, aging and cognitive performance in a cohort of Japanese Americans aged 65 and older: the Kame project. International Psychogeriatrics, 13, 2, 207–23.CrossRefGoogle Scholar
Börsch-Supan, A. and Jürges, H. (eds)2005. The Survey of Health, Ageing and Retirement in Europe – Methodology. MEA Eigenverlag, Mannheim, Germany.Google Scholar
Börsch-Supan, A., Hank, K. and Jürges, H. 2005. A new comprehensive and international view on ageing: introducing the Survey of Health, Ageing and Retirement in Europe. European Journal of Ageing, 2, 4, 245–53.CrossRefGoogle ScholarPubMed
Bosse, R., Aldwin, C. M., Levenson, M. R. and Ekerdt, D. J. 1987. Mental health differences among retirees and workers: findings from the Normative Aging Study. Psychology and Aging, 2, 4, 383–9.CrossRefGoogle ScholarPubMed
Capurso, A., Panza, F., Solfrizzi, V., Capurso, C., Mastroianni, F. and Del Parigi, A. 2000. Age-related cognitive decline: evaluation and prevention strategy. Recenti Progressi in Medicina, 91, 3, 127–34.Google ScholarPubMed
Christensen, H., Mackinnon, A. J., Korten, A. E., Jorm, A. F., Henderson, A. S. and Jacomb, P. 1999. Dispersion in cognitive ability as a function of age: a longitudinal study of an elderly community sample. Aging, Neuropsychology and Cognition, 6, 3, 214–28.CrossRefGoogle Scholar
Coffey, C. E., Wilkinson, W. E., Parashos, I. A., Soady, S. A., Sullivan, R. J., Patterson, L. J., Figiel, G. S., Webb, M. C., Spritzer, C. E. and Djang, W. T. 1992. Quantitative cerebral anatomy of the aging human brain: a cross-sectional study using magnetic resonance imaging. Neurology, 42, 1, 527–36.CrossRefGoogle Scholar
Cohen, S. 2004. Social relationships and health. American Psychologist, 59, 8, 676–84.CrossRefGoogle ScholarPubMed
Cole, M. S., Schaninger, W. S. and Harris, S. G. 2002. The workplace social exchange network: a multilevel, conceptual examination. Group and Organizational Management, 27, 1, 142–67.CrossRefGoogle Scholar
Crowe, M., Andel, R., Pedersen, N. L., Johansson, B. and Gatz, M. 2003. Does participation in leisure activities lead to reduced risk of Alzheimer's disease? A prospective study of Swedish twins. Journal of Gerontology, Series B, Psychological Sciences and Social Sciences, 58, 5, P249–55.CrossRefGoogle ScholarPubMed
Cullum, S., Huppert, F. A., McGee, M., Dening, T., Ahmed, A., Paykel, E. S. and Brayne, C. 2000. Decline across different domains of cognitive function in normal ageing: results of a longitudinal population-based study using CAMCOG. International Journal of Geriatric Psychiatry, 15, 9, 853–62.3.0.CO;2-T>CrossRefGoogle ScholarPubMed
Dave, D., Rashad, I. and Spasojevic, J. 2006. The Effects of Retirement on Physical and Mental Health Outcomes. Working Paper 12123, National Bureau of Economic Research, Cambridge, Massachusetts.CrossRefGoogle Scholar
Deary, I. J., Pattie, A., Taylor, M. D., Whiteman, M. C., Starr, J. M. and Whalley, L. J. 2003. Smoking and cognitive change from age 11 to age 80. Journal of Neurology, Neurosurgery and Psychiatry, 74, 7, 1006–7.CrossRefGoogle ScholarPubMed
Deary, I. J., Whalley, L. J., Lemmon, H., Crawford, J. R. and Starr, J. M. 2000. The stability of individual differences in mental ability from childhood to old age: follow-up of the 1932 Scottish mental survey. Intelligence, 28, 1, 49–55.CrossRefGoogle Scholar
Dik, M. G., Deeg, D. J. H., Visser, M. and Jonker, C. 2003. Early life physical activity and cognition at old age. Journal of Clinical and Experimental Neuropsychology, 25, 5, 643–53.CrossRefGoogle ScholarPubMed
Elias, M. F., Elias, P. K., Sullivan, L. M., Wolf, P. A. and D'Agostino, R. B. 2003. Lower cognitive function in the presence of obesity and hypertension: the Framingham heart study. International Journal of Obesity, 27, 2, 260–8.CrossRefGoogle ScholarPubMed
Elwood, P. C., Gallacher, J. E. J., Hopkinson, C. A., Pickering, J., Rabbitt, P., Stollery, B., Brayne, C., Huppert, F. A. and Bayer, A. 1999. Smoking, drinking and other life style factors and cognitive function in men in the Caerphilly cohort. Journal of Epidemiology and Community Health, 53, 1, 9–14.CrossRefGoogle ScholarPubMed
Engelhardt, H., Buber, I., Skirbekk, V. and Prskawetz, A. 2008. Social Engagement, Behavioural Risks and Cognitive Functioning Among the Aged. European Demographic Research Paper 2008/1, Österreichische Akademie der Wissenschaften [Austrian Academy of Sciences], Vienna. Available online at http://www.oeaw.ac.at/vid/download/edrp_1_08.pdf [Accessed 26 August 2009].Google Scholar
Falleti, M., Sanfilippo, A., Maruff, P., Weih, L. and Phillips, K.-A. 2006. The nature and severity of cognitive impairment associated with adjuvant chemotherapy in women with breast cancer: a meta-analysis of the current literature. Brain and Cognition, 59, 1, 60–70.CrossRefGoogle Scholar
Fillit, H. M., Butler, R. N., O'Connell, A. W., Albert, M. S., Birren, J. E., Cotman, C. W., Greenough, W. T., Gold, P. E., Kramer, A. F., Kuller, L. H., Perls, T. T., Sahagan, B. G. and Tully, T. 2002. Achieving and maintaining cognitive vitality with aging. Mayo Clinic Proceedings, 77, 7, 681–96.CrossRefGoogle ScholarPubMed
Glass, T. A., Mendes de Leon, C., Marottoli, R. A. and Berkman, L. F. 1999. Population-based study of social and productive activities as predictors of survival among elderly Americans. British Medical Journal, 319, 7208, 478–83.CrossRefGoogle ScholarPubMed
Glei, D. A., Landau, D. A., Goldman, N., Chuang, Y., Rodríguez, G. and Weinstein, M. 2005. Participating in social activities helps preserve cognitive function: an analysis of a longitudinal, population-based study of the elderly. International Journal of Epidemiology, 34, 4, 864–71.CrossRefGoogle ScholarPubMed
Gow, A., Pattie, A., Whiteman, M. C. and Deary, I. J. 2005. Social Support Networks, Loneliness and Cognitive Ageing. Poster presented at the British Psychological Society Quinquennial Conference, Manchester, UK, 30 March to 2 April. Available online at http://psy-web.psy.ed.ac.uk/people/agow/BPS-2005.pdf [Accessed 10 September 2008].Google Scholar
Honig, L. S. and Rosenberg, R. N. 2000. Apoptosis and neurologic disease. American Journal of Medicine, 108, 4, 317–30.CrossRefGoogle ScholarPubMed
Horn, J. L. and Cattell, R. 1966. Refinement and test of the theory of fluid and crystallized intelligence. Journal of Educational Psychology, 57, 5, 253–70.CrossRefGoogle Scholar
Horn, J. L. and Cattell, R. 1967. Age differences in fluid and crystallized intelligence. Acta Psychologica, 26, 2, 107–29.CrossRefGoogle ScholarPubMed
James, D. and Coyle, C. 1998. Physical exercise, IQ scores and working memory in older men. Education and Ageing, 13, 1, 37–48.Google Scholar
Jürges, H. 2007. True health vs. response styles: exploring cross-country differences in self-reported health. Health Economics, 16, 2, 163–78.CrossRefGoogle ScholarPubMed
Katzman, R. 1993. Education and the prevalence of dementia and Alzheimer's disease. Neurology, 43, 6, supplement 3, 13–20.CrossRefGoogle ScholarPubMed
Launer, L. J., Andersen, K., Dewey, M. E., Letenneur, L., Ott, A., Amaducci, L. A., Brayne, C., Copeland, J. R., Dartigues, J. F., Kragh-Sorensen, P., Lobo, A., Martinez-Lage, J. M., Stijnen, T. and Hofman, A. 1999. Rates and risk factors for dementia and Alzheimer's disease: results from EURODEM pooled analyses. EURODEM Incidence Research Group and Work Groups. European Studies of Dementia. Neurology, 52, 1, 78–84.CrossRefGoogle Scholar
Le Carret, N., Lafont, S., Mayo, W. and Fabrigoule, C. 2003. The effect of education on cognitive performances and its implication for the constitution of the cognitive reserve. Developmental Neuropsychology, 23, 3, 317–37.CrossRefGoogle ScholarPubMed
Mackinnon, A., Christensen, H., Hofer, S. M., Korten, A. E. and Jorm, A. F. 2003. Use it and still lose it? The association between activity and cognitive performance established using latent growth techniques in a community sample. Aging, Neuropsychology and Cognition, 10, 3, 215–29.CrossRefGoogle Scholar
Maier, H. and Klumb, P. L. 2005. Social participation and survival at older ages: is the effect driven by activity content or context? European Journal of Ageing, 2, 1, 31–9.CrossRefGoogle ScholarPubMed
Maitland, S. B., Intrieri, R. C., Schaie, W. K. and Willis, S. L. 2000. Gender differences and changes in cognitive abilities across the adult life span. Aging, Neuropsychology and Cognition, 7, 1, 32–53.CrossRefGoogle Scholar
McDougall, G. J., Becker, H. and Areheart, K. L. 2006. Older males, cognitive function and alcohol consumption. Issues in Mental Health Nursing, 27, 4, 337–53.CrossRefGoogle ScholarPubMed
McEvoy, G. M. and Cascio, W. F. 1989. Cumulative evidence of the relationship between employee age and job performance. Journal of Applied Psychology, 74, 1, 11–7.CrossRefGoogle Scholar
McGarry, K. 2004. Health and retirement: do changes in health affect retirement expectations? Journal of Human Resources, 39, 3, 624–48.CrossRefGoogle Scholar
McGue, M. and Christensen, K. 2007. Social activity and healthy aging: a study of aging Danish twins. Twin Research and Human Genetics, 10, 2, 255–65.CrossRefGoogle ScholarPubMed
Meeusen, W. and van den Broeck, J. 1977. Efficiency estimation from Cobb-Douglas production functions with composed error. International Economic Review, 18, 2, 435–44.CrossRefGoogle Scholar
Mein, G., Martikainen, P., Hemingway, H., Stansfeld, S. and Marmot, M. 2003. Is retirement good or bad for mental and physical health functioning? Whitehall II longitudinal study of civil servants. Journal of Epidemiology and Community Health, 57, 1, 46–9.CrossRefGoogle ScholarPubMed
Melchior, M., Berkman, L. F., Niedhammer, I., Chea, M. and Goldberg, M. 2003. Social relations and self-reported health: a prospective analysis of the French Gazel cohort. Social Science and Medicine, 56, 8, 1817–30.CrossRefGoogle Scholar
Meyer, J. S., Rauch, G. M., Crawford, K., Rauch, R. A., Konno, S., Akiyama, H., Terayama, Y. and Haque, A. 1999. Risk factors accelerating cerebral degenerative changes, cognitive decline and dementia. International Journal of Geriatric Psychiatry, 14, 12, 1050–61.3.0.CO;2-Z>CrossRefGoogle ScholarPubMed
Newson, R. S. and Kemps, E. B. 2005. General lifestyle activities as a predictor of current cognition and cognitive change. Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 60, 3, 113–21.CrossRefGoogle ScholarPubMed
Norman, S., Tröster, A. I., Fields, J. A. and Brooks, R. 2002. Effects of depression and Parkinson's disease on cognitive functioning. Journal of Neuropsychiatry and Clinical Neurosciences, 14, 1, 31–6.CrossRefGoogle ScholarPubMed
Park, D. C., Nisbett, R. E. and Hedden, T. 1999. Culture, cognition and aging. Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 54, 2, 75–84.CrossRefGoogle Scholar
Prskawetz, A., Mahlberg, B. and Skirbekk, V. 2007. Firm productivity, workforce age and educational structure in Austrian industries in 2001. In Clark, R. L. C., Ogawa, N. and Mason, A. (eds), Population Aging, Intergenerational Transfers and the Macroeconomy. Edward Elgar, Cheltenham, UK, 38–66.Google Scholar
Prskawetz, A., Mahlberg, B., Skirbekk, V., Freund, I., Winkler-Dworak, M., Lindh, T., Malmberg, B., Jans, A.-C., Nordström, O. S. and Andersson, F. 2005. The impact of population ageing on innovation and productivity growth in Europe. Report for Tender VT/2004/454, Forschungsbericht 28, Vienna Institute of Demography, Vienna.Google Scholar
Rasmussen, L. S., Larsen, K., Houx, P., Skovgaard, L. T., Hanning, C. D., Moller, J. T. and the ISPOCD group 2001. The assessment of postoperative cognitive function. Acta Anaesthesiologica Scandinavica, 45, 3, 275–89.CrossRefGoogle ScholarPubMed
Rasquin, S. J., Lodder, R., Ponds, I., Winkens, J., Jolles, J. and Verhey, F. R. J. 2004. Cognitive functioning after stroke: a one-year follow-up study. Dementia and Geriatric Cognitive Disorders, 18, 2, 138–44.CrossRefGoogle ScholarPubMed
Raz, N. 2004. The aging brain: structural changes and their implications for cognitive aging. In Dixon, R. A., Bäckman, L. and Nilsson, L.-G. (eds), New Frontiers in Cognitive Aging. Oxford University Press, Oxford, 115–33.CrossRefGoogle Scholar
Richards, M., Hardy, R. and Wadsworth, M. E. 2003. Does active leisure protect cognition? Evidence from a national birth cohort. Social Science and Medicine, 56, 4, 785–92.CrossRefGoogle ScholarPubMed
Richards, M., Shipley, B., Fuhrer, R. and Wadsworth, M. E. 2004. Cognitive ability in childhood and cognitive decline in mid-life: longitudinal birth cohort study. British Medical Journal, 328, 7439, 552–7.CrossRefGoogle ScholarPubMed
Salokangas, R. K. and Joukamaa, M. 1991. Physical and mental health changes in retirement age. Psychotherapy and Psychosomatics, 55, 2–4, 100–7.CrossRefGoogle ScholarPubMed
Scarmeas, N., Levy, G., Tang, M. X., Manly, J. and Stern, Y. 2001. Influence of leisure activity on the incidence of Alzheimer's disease. Neurology, 57, 12, 2236–42.CrossRefGoogle ScholarPubMed
Scarmeas, N. and Stern, Y. 2003. Cognitive reserve and lifestyle. Journal of Clinical and Experimental Neuropsychology, 25, 5, 625–33.CrossRefGoogle ScholarPubMed
Schaie, K. W. 1994. The course of adult intellectual development. American Psychologist, 49, 4, 304–3.CrossRefGoogle ScholarPubMed
Schaie, K. W. 1996. Intellectual Development in Adulthood: The Seattle Longitudinal Study. Cambridge University Press, New York.Google Scholar
Schaie, K. W. and Willis, S. L. 1986. Can decline in intellectual functioning be reversed? Developmental Psychology, 22, 2, 223–32.CrossRefGoogle Scholar
Schatz, J. and Buzan, R. 2006. Decreased corpus callosum size in sickle cell disease: relationship with cerebral infarcts and cognitive functioning. Journal of the International Neuropsychological Society, 12, 1, 24–33.CrossRefGoogle ScholarPubMed
Schmidt, F. L. and Hunter, J. E. 1998. The validity and utility of selection methods in personnel psychology: practical and theoretical implications of 85 years of research findings. Psychological Bulletin, 124, 2, 262–74.CrossRefGoogle Scholar
Schmidt, R., Mechtler, L., Kinkel, P. R., Fazekas, F., Kinkel, W. R. and Freidl, W. 1993. Cognitive impairment after acute supratentorial stroke: a 6-month follow-up clinical and computed tomographic study. European Archives of Psychiatry and Clinical Neuroscience, 243, 1, 11–15.CrossRefGoogle ScholarPubMed
Schooler, C., Mulatu, M. S. and Oates, G. 1999. The continuing effects of substantively complex work in the intellectual functioning of older workers. Psychology and Aging, 14, 3, 483–506.CrossRefGoogle ScholarPubMed
Schwartzman, A. E., Gold, D., Andres, D., Arbuckle, T. Y. and Chaikelson, J. 1987. Stability of intelligence: a 40 year follow-up. Canadian Journal of Psychology, 41, 2, 244–56.CrossRefGoogle ScholarPubMed
Skirbekk, V. 2008. Age and productivity capacity: descriptions, causes and policy options. Ageing Horizons (Oxford Institute of Ageing), 8, 4–12.Google Scholar
Snowdon, D. A., Kemper, S. J., Mortimer, J. A., Greiner, L. H., Wekstein, D. R. and Markesbery, W. R. 1996. Linguistic ability in early life and cognitive function and Alzheimer's disease in later life. Journal of the American Medical Association, 275, 7, 528–32.CrossRefGoogle Scholar
Sugisawa, A., Sugisawa, H., Nakatani, Y. and Shibata, H. 1997. Effect of retirement on mental health and social well-being among elderly Japanese. Nippon Koshu Eisei Zasshi, 44, 2, 123–30.Google ScholarPubMed
Tesch-Römer, C. and von Kondratowitz, H. J. 2006. Comparative ageing research: a flourishing field in need of theoretical cultivation. European Journal of Ageing, 3, 3, 155–67.CrossRefGoogle ScholarPubMed
Tomassini, C., Glaser, K., Wolf, D. A., Broese van Groenou, M. I. and Grundy, E. 2004. Living arrangements among older people: an overview of trends in Europe and the USA. Population Trends, 115, 24–34.Google Scholar
United Nations Educational, Scientific and Cultural Organization (UNESCO) 1997. International Standard Classification of Education (ISCED) 1997. UNESCO, Paris. Available online at http://www.unesco.org/education/information/nfsunesco/doc/isced_1997.htm [Accessed 28 August 2009].Google Scholar
United Nations Organisation (UNO) 2007. World Population Prospects: The 2006 Revision. UNO, New York.Google Scholar
Verhaegen, P. and Salthouse, T. A. 1997. Meta-analyses of age-cognition relations in adulthood: estimates of linear and nonlinear age effects and structural models. Psychological Bulletin, 122, 3, 231–49.CrossRefGoogle Scholar
Warr, P. 1994. Age and employment. In Triandis, H., Dunnette, M. and Hough, L. (eds), Handbook of Industrial and Organizational Psychology. Second edition, Consulting Psychologist Press, Thousand Oaks, California, 485–550.Google Scholar
Whalley, L. J., Starr, J. M., Athawes, R., Hunter, D., Pattie, A. and Deary, I. J. 2000. Childhood mental ability and dementia. Neurology, 55, 10, 1455–9.CrossRefGoogle ScholarPubMed
Wilson, R. S., Barnes, L. L., Mendes de Leon, C. F., Aggarwal, N. T., Schneider, J. S., Bach, J., Pilat, J., Beckett, L. A., Arnold, S. E., Evans, D. A. and Bennett, D. A. 2002 a. Depressive symptoms, cognitive decline, and risk of AD in older persons. Neurology, 59, 3, 364–370.CrossRefGoogle ScholarPubMed
Wilson, R., Krueger, K. R., Arnold, S. E., Schneider, J. A., Kelly, J. F., Barnes, L. L., Tang, Y. and Bennett, D. A. 2007. Loneliness and risk of Alzheimer disease. Archives of General Psychiatry, 64, 2, 234–40.CrossRefGoogle ScholarPubMed
Wilson, R. S., Mendes De Leon, C. F., Barnes, L. L., Schneider, J. A., Bienias, J. L., Evans, D. A. and Bennett, D. A. 2002 b. Participation in cognitively stimulating activities and risk of incident Alzheimer disease. Journal of the American Medical Association, 287, 6, 742–8.CrossRefGoogle ScholarPubMed
Winocur, G., Vardy, J., Binns, M. A., Kerr, L. and Tannock, I. 2006. The effects of the anti-cancer drugs, methotrexate and 5-fluorouracil, on cognitive function in mice. Pharmacology, Biochemistry and Behavior, 85, 1, 66–75.CrossRefGoogle ScholarPubMed
Zhang, Z. 2006. Gender differentials in cognitive impairment and decline of the oldest old in China. Journals of Gerontology, Series B: Psychological Sciences and Social Sciences, 61, 2, S107–15.CrossRefGoogle ScholarPubMed