Duncan J McLauchlan1,2,3, Thomas Lancaster1,2,3, David Craufurd4,5, David E J Linden1,2,3,6, Anne E Rosser1,2,7. 1. Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, UK. 2. MRC Center for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff, UK. 3. Cardiff University Brain Research Imaging Center, Cardiff University, Cardiff, UK. 4. Manchester Center for Genomic Medicine, Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Center, Manchester, UK. 5. St. Mary's Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Center, Manchester, UK. 6. School for Mental Health and Neuroscience, Fac. Health, Medicine and Life Sciences, Maastricht University, Maastricht, Netherlands. 7. Brain Repair Group, School of Biosciences, Cardiff University, Cardiff, UK.
Abstract
BACKGROUND: Apathy is a deficit in goal-directed behavior that significantly affects quality of life and function. It is common in Huntington's disease and other disorders affecting corticostriatal pathways. Deficits in processing of reward, altered effort, and executive dysfunction are associated with apathy in other disorders, but the cognitive processes leading to apathy in Huntington's disease remain largely unknown. A previously reported deficit in learning from losses in Huntington's disease raises the possibility of a hitherto unrecognized mechanism leading to apathy. This study's objective was to delineate the cognitive processes associated with apathy in HD. METHODS: We tested 51 Huntington's disease participants and 26 controls on a battery of novel and established measures to assess the contribution to apathy in Huntington's disease of executive function, reward value, reward-effort calculations, instrumental learning, and response to reward and loss. RESULTS: Huntington's disase participants had deficits in instrumental learning with impaired response to loss, but no evidence to suggest altered reward-related behavior or effort. We also saw an executive dysfunction contribution to apathy in Huntington's disease. DISCUSSION: We report the novel finding that apathy in Huntington's disease is associated with blunted responses to losses and impaired instrumental learning. This association is consistent with the known early degeneration of the indirect pathway and amygdala involvement in apathy in Huntington's disease, but is previously unreported in any disorder. In keeping with the comparative preservation of the ventral striatum and orbitofrontal cortex in Huntington's disease, reward valuation and reward-effort calculations did not contribute to apathy.
BACKGROUND: Apathy is a deficit in goal-directed behavior that significantly affects quality of life and function. It is common in Huntington's disease and other disorders affecting corticostriatal pathways. Deficits in processing of reward, altered effort, and executive dysfunction are associated with apathy in other disorders, but the cognitive processes leading to apathy in Huntington's disease remain largely unknown. A previously reported deficit in learning from losses in Huntington's disease raises the possibility of a hitherto unrecognized mechanism leading to apathy. This study's objective was to delineate the cognitive processes associated with apathy in HD. METHODS: We tested 51 Huntington's diseaseparticipants and 26 controls on a battery of novel and established measures to assess the contribution to apathy in Huntington's disease of executive function, reward value, reward-effort calculations, instrumental learning, and response to reward and loss. RESULTS: Huntington's disase participants had deficits in instrumental learning with impaired response to loss, but no evidence to suggest altered reward-related behavior or effort. We also saw an executive dysfunction contribution to apathy in Huntington's disease. DISCUSSION: We report the novel finding that apathy in Huntington's disease is associated with blunted responses to losses and impaired instrumental learning. This association is consistent with the known early degeneration of the indirect pathway and amygdala involvement in apathy in Huntington's disease, but is previously unreported in any disorder. In keeping with the comparative preservation of the ventral striatum and orbitofrontal cortex in Huntington's disease, reward valuation and reward-effort calculations did not contribute to apathy.
Authors: Cheney J G Drew; Feras Sharouf; Elizabeth Randell; Lucy Brookes-Howell; Kim Smallman; Bernadette Sewell; Astrid Burrell; Nigel Kirby; Laura Mills; Sophie Precious; Philip Pallmann; David Gillespie; Kerry Hood; Monica Busse; William P Gray; Anne Rosser Journal: Brain Commun Date: 2021-01-19