Alternative Treatments To Prevent Cognitive Decline in Older Adults With Depression and Anxiety

Context - Review of Literature

Depression and anxiety are common in older adults affecting 300,000-600,000 Canadian seniors annually1. About 30% of patients aged ≥60 suffering from these conditions have cognitive dysfunction across several domains 2,3, and an episode of depression or anxiety in this population increases the odds of developing dementia by two-fold4-6. Cognitive impairment and dementia are major causes of disability and dependency among older people worldwide. These conditions confer poor quality of life and place people in an extremely vulnerable condition7.

Adequate treatment of a depressive/anxiety episode can improve short- and longer-term cognition in executive, language, memory, and processing speed domains8. Because depression and anxiety in late-life are reversible to a certain extent and they are important risk factors for subsequent cognitive decline; improving these conditions can ultimately improve quality of life, lengthen the independent living of vulnerable people, reduces stress and caregiver burden. Unfortunately, existing pharmacotherapy treatments for late-life depression and anxiety have limited effectiveness (50-60% of patients are treatment-resistant), are poorly tolerated, and access is difficult due to the absence of trained personnel. Additionally, there are long waiting lists (up to 12 months) in most Canadian provinces and interventions are administered one-on-one, which is costly for the health system9. Thus, there is an urgent need for novel treatments for late-life depression and anxiety that can also improve cognition and even potentially prevent dementia in the longer-term.

Mindfulness-based cognitive therapy (MBCT) is a group intervention that teaches mindfulness meditation (non-judgemental awareness of the present moment)10. MBCT is scalable, accessible, cost efficient, and has been shown to decrease symptoms of depression, anxiety and other psychiatric disorders11. Additionally, MBCT is associated with improved quality of life 12, disability, caregiver burden and stress13. Studies conducted by our own group have found that mindfulness meditation is feasible and well-tolerated in older patients suffering from depression and anxiety14. While the neural mechanisms of MBCT are not fully understood, previous work in younger adults has shown that this intervention increases grey matter density in the brain's hippocampus, known to be involved in learning, memory and stress15. Moreover, long-term meditation practitioners displayed decreased age-related degeneration of the hippocampus16 These findings are relevant because decreased hippocampal volume17,18 and brain functional connectivity (default mode network)19 are commonly found in depressed patients. Additionally, these findings are also observed early in Alzheimer's disease and are associated with cognitive decline20.

Study Purpose and Rationale

Despite all this evidence, it remains unknown whether MBCT can strengthen brain networks, increase brain volume, and bolster cognition in depressed and anxious older adults. To our knowledge, previous mindfulness studies assessing cognition in older adults have not used MBCT nor have used neuroimaging techniques in depressed and anxious participants. Cognitive assessments in previous studies were not sensitive enough and did not use an appropriate active control group.

Thus, to address these issues, Investigators will conduct a randomized controlled trial (RCT) in late-life depression and anxiety using a standardized MBCT intervention, an appropriate active control group, a more sensitive neurocognitive test battery and the use of neuroimaging methods. In this pilot neuroimaging study, Investigators wish to assess the effects of a standard Mindfulness-Based Cognitive Therapy (MBCT) compared to an active control, Health Enhancement Program (HEP), on a number of clinical and biologically relevant outcomes, with a focus on structural and functional integrity of the default-mode network.