Late life depression (LLD) affects 5 million American seniors yearly with $1.81 billion in direct health-care costs. Biomarkers of LLD have consistently been linked to elevated dementia risk. Mindfulness-based cognitive therapy (MBCT) holds promise for treating symptoms of depression, ameliorating cognitive deficits and preventing decline in older adults by targeting brain circuits implicated in memory and attention. While preliminary findings are promising, the effects of mindfulness on cognition and brain markers have not been assessed in older adults with depression who are especially vulnerable to cognitive decline. This proposed research will explore 1) whether MBCT's mechanism of action in treating symptoms of depression and preventing cognitive decline is behavioural activation or mindfulness, two components of MBCT, 2) the role of environmental factors, 3) whether benefits persist in the medium term, and 4) the persistence of key cognitive and brain markers associated with the treatment of LLD.~Two-hundred and thirteen (n = 213) patients with LLD will be recruited at various centres in Montreal (affiliated with McGill University, Université de Montréal and University of Toronto). Participants will undergo stratified randomization to either MBCT or Health Enhancement Program (HEP) intervention groups. The investigators will assess changes in (1) depression severity, (2) processing speed and executive functioning, (3) hippocampal volume, resting-state functional connectivity and vascular risk factors, and (4) other exploratory physiological and mood-based measures, at baseline (0 weeks), post intervention (8 weeks), and 26 weeks after baseline. Raters and clinicians will be blinded to group allocation while participants will be blinded to the study hypotheses.~The proposed study will assess the clinical potential of MBCT to improve symptoms of depression, as well as examine its impact on cognitive impairments and neurobiological markers, and thus inform its use as a promising adjunct in the treatment of LLD. If MBCT is found to be effective in treating LLD and preventing cognitive decline, the potential exists to implement this intervention at the study sites, across Canada, and internationally.
Study Design & Recruitment: Phase III randomized controlled trial (RCT) with 200 patients. Participants with a diagnosis of late-life depression (LLD), excluding dementia and other psychiatric comorbidities, will be recruited at three health networks. LLD patients had no earlier depressive episodes before the age of 65.~Interventions: Mindfulness-based Cognitive Therapy (MBCT) or Health Enhancement Program (HEP) for 8-weeks, in addition to TAU. MBCT and HEP will have the same group sizes, meeting frequency, and amount of home practice. HEP is a recognized active control where participants learn about diet and exercise, but not meditation.