Abstract
An active cognitive lifestyle has been suggested to have a protective role in the long-term maintenance of cognition. Amongst healthy older adults, more managerial or supervisory experiences in midlife are linked to a slower hippocampal atrophy rate in late life. Yet whether similar links exist in individuals with Mild Cognitive Impairment (MCI) is not known, nor whether these differences have any functional implications. 68 volunteers from the Sydney SMART Trial, diagnosed with non-amnestic MCI, were divided into high and low managerial experience (HME/LME) during their working life. All participants underwent neuropsychological testing, structural and resting-state functional MRI. Group comparisons were performed on hippocampal volume, morphology, hippocampal seed-based functional connectivity, memory and executive function and self-ratings of memory proficiency. HME was linked to better memory function (p = 0.024), mediated by larger hippocampal volume (p = 0.025). More specifically, deformation analysis found HME had relatively more volume in the CA1 sub-region of the hippocampus (p < 0.05). Paradoxically, this group rated their memory proficiency worse (p = 0.004), a result correlated with diminished functional connectivity between the right hippocampus and right prefrontal cortex (p < 0.001). Finally, hierarchical regression modelling substantiated this double dissociation.
Highlights
Cognitive lifestyle refers to lifetime patterns of participation in educational, occupational, social and leisure activities and is increasingly recognised as a protective and modifiable risk factor in the development of dementia
For this study further exclusion criteria were applied: 1) non-retired participants were excluded (n = 11) because of our specific interest on the long term correlates of managerial experience in working life on brain health after retirement (Valenzuela and Sachdev 2007); 2) Amnestic Mild Cognitive Impairment (MCI) based on an age-scaled score on the Logical Memory II WMS test of less than 5 (i.e.,
Participants had mild cognitive deficits as indicated by the majority of ADASCOG scores in the MCI range of 8–9 (Pyo et al 2006), and negligible depressive symptoms, consistent with SMART entry criteria. Their overall cognitive lifestyle (LEQ = 88.4) was similar to that reported for the population-based Sydney Memory & Ageing Study (healthy aged average 93.4 (Valenzuela et al 2013))
Summary
Cognitive lifestyle refers to lifetime patterns of participation in educational, occupational, social and leisure activities and is increasingly recognised as a protective and modifiable risk factor in the development of dementia. In a population-based study of healthy older adults we showed that the link between active cognitive lifestyle and protection from hippocampal atrophy was primarily driven by high-level managerial and supervisory experience in midlife – ex-high level managers or supervisors had significantly larger hippocampal volume and slower hippocampal atrophy rate than those who had never been in charge of others in their working life (Suo et al 2012). This is interesting because a fast rate of hippocampal atrophy or smaller hippocampal volume is a sensitive and specific predictor of dementia (Jack et al 2000) (Risacher et al 2010) (Frankó et al 2013) (den Heijer et al 2006). We tried to integrate hippocampal structure, function, objective memory and subjective concerns into one statistical model
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