The joint memory effect: challenging the selfish stigma in Huntington's disease?

The prevalent belief that individuals with Huntington's disease exhibit selfish behaviour, disregarding the thoughts, feelings and actions of others, has been challenged by patient organizations and clinical experts. To further investigate this issue and study whether participants with Huntington's disease can pay attention to others, a joint memory task was carried out in patients with Huntington's disease with and without a partner. This study involved 69 participants at an early stage of Huntington's disease and 56 healthy controls from the UK, France and Germany, who participated in the international Repair-HD multicentre study (NCT03119246). Participants completed a semantic categorization task across three categories: animals, fruits and vegetables and manufactured objects. They performed the task either alone (Alone condition) or with the examiner acting as a partner (Pair condition). In the Pair condition, the participant was assigned one category, their partner was assigned another and one category was left unassigned. Afterwards, participants engaged in a surprise free recall task to remember as many words as possible. Words not assigned to anyone were considered socially irrelevant in contrast to the ones assigned to the participant and to the partner. Both groups demonstrated the expected self-prioritization effect, recalling their assigned words better than their partner's or unassigned words in both conditions. Additionally, a joint memory effect was observed, with better recall for the partner's assigned words than the unassigned words in the Pair condition (controls: difference = 0.45,