Perceived loneliness causes a global health burden on older adults. Mindfulness training may be a feasible solution. Through our study, we expect that comprehensive and convincing neuroscientific evidence may support the efficacy underpinning mindfulness training in loneliness reduction.

In this aging and highly industrial society, elderly depression, particularly elderly loneliness, is a growing societal issue. Perceived loneliness not only causes tremendous suffering, disability, cognitive decline, and risk of dementia but also leads to increased mortality. Despite worldwide effort to solve the growing prevalence of loneliness in older adults, no single intervention stands out as universally effective and practical. The exact neural mechanism of loneliness and how the intervention against loneliness takes its effect in the brain remain unclear. Prior studies have indicated that perceived loneliness is associated with distorted cognition toward interpersonal interaction and heightened sympathetic nerve system.Mindfulness training is a discipline that the older adults in our society can readily relate to because the philosophy of mindfulness is similar to Buddhism. Mindfulness trains people to be aware of the surrounding environment and their presence in this environment. Combining the exercises of deep breathing and relaxation, one is taught to be aware of the emotion of oneself to regulate emotion. Mindfulness-based stress reduction (MBSR), a validated and systemized intervention, has been applied to the treatment of depression, anxiety, and insomnia. On the basis of the theory of mindfulness, the investigators estimate that mindfulness can reduce loneliness as well. Thus, the investigators aim to use MBSR in a group of older adults with depression to reduce loneliness. Our previous studies demonstrated that loneliness decreases the grey matter volume in reward system, disrupts the white matter structure, and heightens default-mode network activation. By combining a wearable device for sleep monitoring, heart rate variability measurement, and immune-related cytokine blood test, the investigators can associate these changes with clinical loneliness reduction and brain changes from magnetic resonance imaging. The investigators hope to validate MBSR as an effective intervention against loneliness and explore the supporting neural mechanism.

Inclusion Criteria:

1. Age > 55 years.
2. Major depressive disorder (MDD).

Exclusion Criteria:

1. Inability to provide informed consent.
2. Dementia, as defined by MMSE < 24 (<17 if illiterate or no education) and clinical evidence of dementia based on DSM-5 criteria.
3. Lifetime diagnosis of bipolar I or II disorder, schizophrenia, schizoaffective disorder, schizophreniform disorder, delusional disorder, or current psychotic symptoms.
4. Abuse of or dependence on alcohol or other substances within the past 3 months, and confirmed by study physician interview.
5. High risk for suicide (e.g., active suicide ideation and/or current/recent intent or plan) AND unable to be managed safely in the clinical trial (e.g., unwilling to be hospitalized). Urgent psychiatric referral will be made in these cases.
6. Non-correctable clinically significant sensory impairment (i.e., cannot hear well enough to cooperate with interview).
7. Unstable medical illness, including delirium, uncontrolled diabetes mellitus, hypertension, hyperlipidemia, or cerebrovascular or cardiovascular risk factors that are not under medical management.
8. Currently under psychotherapy or taking regular meditation or yoga practice (or had experience in these activities)