A biological framework for understanding and modulating apathy in healthy people

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As we get older our ability to do mentally and physically demanding tasks declines. However, research shows that we also lose motivation to complete mentally and physically demanding tasks through the effects of aging. Apathy - a reduction in the willingness to engage and perform mentally and physically demanding tasks - is widespread in mild forms in young adults, but crucially, it significantly increases as we age, hampering the daily lives of the elderly. Apathy in young adults may also have considerable long-term effects with significant costs, affecting education, employment and civic engagement. Despite the importance of keeping motivated for healthy aging, very little is known about the biological processes that lead to apathy in the young or the elderly. In this research I aim to establish a biological model of apathy. I will test specific ideas developed from animal models of the processes in the brain that lead to reduced motivation. Using this models as a basis, I will test whether key pathways in the brain that lead animals to stop doing mentally and physically demanding tasks are also responsible for causing individual differences in how motivated people are . Using new mathematical approaches in conjunction with brain imaging techniques in healthy young adults I will build a biologically based model of apathy in the young and the elderly. Using modern non-invasive brain stimulation techniques I will then explore whether motivation can be increased by stimulating parts of the brain we predict are involved in motivation based on our animal model.There are three key questions this research will address: (1) To what extent is motivation reduced in the elderly? Most research that has looked at motivation in aging, has used questionnaires, asking people about how motivated they feel. Unfortunately, these do not provide us with a model that can explain the biology behind apathy. Using two new tasks, the designs of which are based on tasks used to explore animal decision-making, I will examine how motivated the elderly are compared to young adults to do mentally and physically demanding tasks and how motivated they are to overcome fatigue. (2) What is the biology of apathy Research into the processes that underpin motivation in rats, birds and monkeys has provided us with a models of the pathwys in the brain that are crucial for keeping animals motivated. However, it is unknown what the links are between how these 'motivational circuits' work, apathy in humans, and changes in motivation through aging. Using functional Magnetic Resonance Imaging (which can tell us about whether an area is 'activated' by doing a task) and Diffusion Tensor Imaging (which can tell us about how strongly connected to each other brain areas are) I will test whether the same pathways in the brain that are responsible for motivating animals are also responsible for motivating humans. I will then test whether changes in these pathways in older people leads to them being less motivated.(3) Can we increase motivation in the elderly and the apathetic young by stimulating the brain? Once my proposed model of apathy has been tested, I will have identified I will have identified regions that can targeted by brain stimulation techniques. By stimulating these areas in a particular way, I predict that we can increase people's willingness to overcome cognitive and physical demands, and make people less influenced by fatigue. That is, I aim to try and increase how motivated people are, in order to develop potential techniques for ameliorating apathy.This work will provide the first biological model of apathy and how changes in the brain can lead to greater levels of apathy in the elderly. This model will provide researchers, clinicians and industry with a framework on which to base therapeutic techniques and technologies aimed at increasing motivation.