Emotion regulation and well-being as we age: Implications of cognitive decline and prefrontal atrophy for corticolimbic function

With a projected rise of 32% in the population aged 65 and over by 2033, it is crucial that we understand and promote processes that support healthy ageing. Even in the absence of neurodegenerative diseases, such as Alzheimer's disease, ageing involves a loss of brain matter that starts in young adulthood and accelerates around mid-life. These brain changes are paired with changes in thought-related, mental abilities, such as memory, attention, planning, and motor action, generally termed "cognitive" abilities. While we know a great deal about how these age-related brain changes map onto changes in cognitive abilities, less is known about how they impact our emotional wellbeing. However, there is overlap in the brain systems involved in some of these cognitive abilities and those involved in dealing with emotions appropriately.

If these brain systems deteriorate with age, then do older adults deal with emotional situations less well, or do they use different brain systems to maintain wellbeing and happiness in daily life? Large survey studies have reported an increase in positive emotion with age, with some psychologists suggesting an improvement in the skills to regulate one's emotions. We have also learned from prior research that individuals differ in the extent to which their cognitive abilities change with advancing age. What has not to date been studied is how these age-related individual differences in cognitive ability associated with differences in the structure of the brain affect our ability to appropriately regulate emotion.

The aim of this research is to identify how emotion regulatory ability in middle- to older-aged individuals, who vary in the extent to which their cognitive ability has changed in recent years, is impacted by age-related brain changes and how the neural circuitry may adapt to compensate for brain matter loss. We will further test how cognitive and emotion regulatory ability relate to happiness and wellbeing in daily life. We will ask 70 volunteer members aged 55 - 85 who are part of the University of Reading's Older Adult Research Panel to participate in our study, half of whom have experienced a decline in cognitive ability measured over the previous 3 visits, and half whose cognitive ability has remained stable. Twenty younger adults will also be recruited to control for age differences in emotion regulation in the absence of cognitive decline or brain matter loss.

Using Magnetic Resonance Imaging (MRI), we will obtain structural brain scans, as well as a functional scan while performing an emotion regulation task. Physiological and behavioural measures will be used to assess emotional responses. Cognitive tests will be performed outside the scanner, and participants will be asked to report their wellbeing and provide saliva samples to quantify daily fluctuations in the stress hormone cortisol. Employing the latest analysis techniques combining brain imaging data with other measures, we will assess the extent to which individuals who have experienced brain matter loss compensate by activating their brains differently when regulating emotion. We will examine the relationship between the ability to regulate emotion, even in the face of decline in cognitive ability and brain matter, and healthy diurnal cortisol pattern and self-reported wellbeing. This research forms the building blocks to understanding how older adults can successfully adapt to stressful events by effectively regulating their emotions, and will directly inform the design of intervention programmes to promote lifelong wellbeing.

Ageing is associated with age-related brain atrophy, affecting regions such as the prefrontal cortex (PFC), involved in executive function (EF), more strongly than other cortical regions of the brain. A lateral PFC network similar to that involved in EF has been identified in emotion regulation whilst individual differences in recruitment of medial parts of the PFC have been associated with wellbeing. This suggests that neural loss in the PFC should impact emotion regulatory ability and wellbeing. However, some studies suggest sustained emotion regulatory ability with ageing, although it is unknown the extent to which older adults in these studies experienced neural tissue loss and/or cognitive decline. We propose to study 70 adults aged 55-85, 35 of whom have experienced cognitive decline, as well as 20 younger adults. We will collect structural and functional MRI augmented with psychophysiological measures of regulatory success, whilst participants perform an emotion regulation task. Behavioural performance on cognitive tasks will be assessed, and salivary cortisol provided over the course of 3 days, and self-reported wellbeing will also be obtained. We will test whether functional plasticity, characterised by the recruitment of a different, more medially located, PFC network, underlies a maintained ability to regulate emotions in older adults, even those experiencing cognitive decline and lateral PFC atrophy. A lateral-medial shift in PFC recruitment is predicted to be more marked with increasing atrophy in individuals whose wellbeing is maintained. Given the paucity of data on cognitive decline and emotion regulation, we will consider the alternative scenario that individuals experiencing cognitive decline and PFC atrophy have a compromised emotion regulatory ability. The findings are expected to advance our understanding of factors impacting older adults' ability to adapt to cortical atrophy and to inform intervention programmes to promote successful ageing.

With greater emphasis being placed on the management of wellbeing by governments around the world, the extent to which emotion regulation is associated with brain health in later life has direct consequences for social, political, and economical policies. A growing interest in lifelong health and wellbeing is evidenced by the UK government's recent announcement to measure happiness, and by the recent movement Action for Happiness founded by Lord Layard in 2010 and led by leading experts in the field. The movement already has 13,000 followers worldwide. We argue that a vital key to wellbeing and happiness is flexible and adept emotion regulation. At a time when the changing demographics of an increasing ageing population is challenging national policies, the output of our research is expected to contribute to the discussion of how wellbeing, particularly in older age, can be achieved.

This research will likely impact public health policies in the future. Firstly, the findings will undoubtedly underscore the importance across the lifespan of not just physical, but also mental health, a topic still met with prejudice and resistance within the public domain. It is anticipated that the presentation of biological findings, in the form of the impact of age on the brain structure and function even in healthy ageing, will provide weight and credence to the message that functional plasticity can to a degree overcome age-related changes in neural structure and associated cognitive and emotional function. Secondly, the findings will inform prevention and intervention programmes, for example in the form of physical or mental training, which will help successful emotion regulation, thereby ultimately leading to a happier, more fulfilling life.

The PI currently holds a BBSRC CASE studentship with Unilever that is complementary to the research proposed here. Following on from Unilever's Heart Age calculator to promote awareness of heart disease and stroke, Unilever's interest in this project is the development of health programmes to promote vitality and healthy ageing. The proposed research will provide important clues for an intervention programme based on cognitive and/or emotion regulation training. Such programmes can take the form of mental training, focusing on reappraising negative information in a less negative light, or focusing on cognitive training. The development and establishment of intervention programmes to promote wellbeing is of great interest to companies such as Unilever.

Within health care, there is a move away from longevity as the sole measure of the nation's wellness to a more focused approach on quality of life. Faced with an ageing population and associated increase in health care demand, there is a considerable interest in promoting the management of wellness. The issue of later life wellbeing is key to lessen the burden on long-term health care, lower the impact of later-life depression and promote continued involvement in society by the elderly. The predicted outcomes of this research will make the links between emotion regulation, physical health and brain health explicit, which will provide health practitioners and policy makers with tangible information to help change attitudes of the general public towards the prevailingly dichotomised perceptions of mental and physical health.