Patterns of cognitive performance in healthy ageing in northern Portugal: a cross-sectional analysis

The Minho Integrative Neuroscience Database (MIND)-Ageing project aims to identify predictors of healthy cognitive ageing, including socio-demographic factors. In this exploratory analysis we sought to establish baseline cohorts for longitudinal assessment of age-related changes in cognition.

Methods
The population sample (472 individuals) was strictly a convenient one, but similar to the Portuguese population in the age profile. Participants older than 55 years of age were included if they did not present defined disabling pathologies or dementia. A standardized clinical interview was conducted to assess medical history and a battery of neuropsychological tests was administered to characterize global cognition (Mini Mental State Examination), memory and executive functions (Selective Reminding Test; Stroop Color and Word Test; and Block Design subtest of the Wechsler Adult Intelligence Scale). Cross-sectional analysis of the neuropsychological performance with individual characteristics such as age, gender, educational level and setting (retirement home, senior university, day care center or community), allowed the establishment of baseline clusters for subsequent longitudinal studies.

Results
Based on different socio-demographic characteristics, four main clusters that group distinctive patterns of cognitive performance were identified. The type of institution where the elders were sampled from, together with the level of formal education, were the major hierarchal factors for individual distribution in the four clusters. Of notice, education seems to delay the cognitive decline that is associated with age in all clusters.

Conclusions
Social-inclusion/engagement and education seem to have a protective effect on mental ageing, although this effect may not be effective in the eldest elders.
This study is integrated in the ‘‘Maintaining health in old age through homeostasis (SWITCHBOX)’’ collaborative project funded by the European Commission FP7 initiative (grant HEALTH-F2-2010-259772). NS, JAP and JC are main team members of the European consortium SWITCHBOX (http://www.switchbox-online.eu/). The study was also supported by the Calouste Gulbenkian Foundation (grant JG0495). ACP and AS were supported by ‘‘Compromisso com a Ciência 2007’’ and NCS by SFRH/BPD/51057/2010, post-doctoral fellowships, funded by the Fundação para a Ciência e Tecnologia (FCT), Portugal. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.