Abstract
ObjectiveAgeing is associated with changes in cognition in some, but not all domains. In young–old adults, defined as persons aged 65–84 years, baseline cognitive function has been shown to impact on cognitive trajectories. Whether similar patterns occur in the very‐old, defined as persons aged 85 years and over, is not known.MethodsLongitudinal changes (5 years' follow‐up) in global and domain specific cognitive function including memory, attention and speed were investigated in participants from the Newcastle 85+ Study (n = 845). At baseline, participants were grouped using Mini‐Mental State Examination cut‐off scores and dementia status into the following: not impaired, mildly impaired or severely impaired/dementia groups.ResultsOnly a limited number of cognitive measures showed significant decline in performance over time. Where observed, change generally occurred only in the severely impaired group. In the severely impaired group, small differences in baseline age were associated with poorer performance over time on most measures. Education was not protective against cognitive decline in any group.ConclusionsThere are individuals who maintain a high level of cognitive function or only show mild impairments even into their ninth decade of life. This group of successful cognitive agers may provide insight for identifying predictors of cognitive integrity in later life. In individuals with severe impairment, cognitive performance shows significant decline over time, especially in measures of attention and speed. Further work to identify those individuals at highest risk of cognitive decline is necessary to implement early support and intervention strategies in this rapidly expanding age group. © 2017 The Authors. International Journal of Geriatric Psychiatry published by John Wiley & Sons Ltd.
Highlights
Longitudinal studies have reported large individual variability in cognitive performance in older aged adults with some individuals showing a decline in functioning, others remaining stable and some even improving (Brayne et al, 1992; Lyketsos et al, 1999; Howieson et al, 2003; Terrera et al, 2010)
There were no significant differences in age at baseline, gender, educational attainment and prevalence of hypertension, diabetes, peripheral vascular disease (PVD) or ischaemic heart disease (IHD) by cognitive group
We examined the trajectories of cognitive performance on measures of global cognitive function, memory, attention and speed in different groups of very-old individuals defined by Mini-Mental State Examination (MMSE) scores and dementia status
Summary
Longitudinal studies have reported large individual variability in cognitive performance in older aged adults with some individuals showing a decline in functioning, others remaining stable and some even improving (Brayne et al, 1992; Lyketsos et al, 1999; Howieson et al, 2003; Terrera et al, 2010). Studies investigating trajectories of cognitive function in older populations have largely been derived from samples of young–old persons (e.g. 65–84 years) or samples with very broad age ranges (e.g. from mid to later life). As such, they may not be representative of the very-old population who are a unique survivor cohort. Individuals aged 85 years and over may have greater sensory (e.g. vision and hearing) and physical impairment, and comorbidities that may influence cognitive performance (Collerton et al, 2009; Jefferis et al, 2013) They may form a select cohort characterised by a more protective biological profile and have better health or lifestyles that increase resilience. While research suggests that cognitive impairment is common in very-old age, it may not necessarily be inevitable (Kliegel et al, 2004)
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