Subthreshold Depression
Conditions
Keywords
Subthreshold depression, Subclinical depression, Dietary intervention, Mediterranean diet, Gut microbiome, Oral microbiome, Nutritional psychiatry, Microbiota-gut-brain axis
Brief summary
This randomized controlled trial evaluates the efficacy of an 8-week dietary education intervention in adults with subthreshold depression. Participants will be randomly assigned in a 1:1 ratio to either a dietary education intervention or a befriending control condition. The dietary intervention consists of online dietary education and counseling designed to encourage a Mediterranean dietary pattern. The control group will receive online befriending sessions of similar frequency and duration. The study will evaluate changes in depressive symptoms and investigate changes in oral and gut microbiota, dietary measures, psychiatric symptoms, metabolic measures, and neurobiological markers.
Detailed description
Subthreshold depression is characterized by clinically significant depressive symptoms that do not meet the full diagnostic criteria for major depressive disorder and represents an important opportunity for early intervention. Emerging evidence suggests that diet and the gut microbiome may be involved in mental health through the microbiota-gut-brain axis. However, evidence regarding dietary interventions specifically for individuals with subthreshold depression is limited, particularly in Asian populations, and the mechanisms linking dietary changes with depressive symptoms remain incompletely understood. The MIND-Trial is an 8-week, parallel-group, open-label randomized controlled trial involving 64 adults with subthreshold depression. Participants will be randomized 1:1 to a dietary education intervention or a befriending control condition. Participants assigned to the intervention will receive online dietary education and counseling every two weeks, incorporating tailored dietary recommendations and structured goal setting to encourage a Mediterranean dietary pattern. Participants assigned to the control condition will receive online befriending sessions at the same frequency and duration, involving conversations on neutral topics. The study will evaluate depressive symptoms as well as dietary adherence, other psychiatric and gastrointestinal symptoms, anthropometric measures, oral and gut microbiota, metabolites, and neurobiological markers.
Interventions
BEHAVIORALMediterranean-Style Dietary Education Program
An 8-week online dietary education and counseling program delivered every two weeks, incorporating tailored dietary recommendations and structured goal setting to encourage adoption of a Mediterranean dietary pattern.
BEHAVIORALBefriending
Online befriending sessions delivered at the same frequency and duration as the dietary education intervention. Sessions consist of conversations on neutral topics intended to maintain engagement and control for nonspecific factors such as attention, treatment expectancy, and engagement.
Sponsors
Institute of Mental Health, Singapore
Nanyang Technological University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
21 Years to 60 Years
Healthy volunteers
No
Inclusion criteria
* Male or female, aged 21 to 60 years. * Meets the operational diagnostic criteria for subthreshold depression. * Has not been following a Mediterranean-style diet, based on self-report and a - Mediterranean Diet Adherence Screener (MEDAS) score ≤9. * Able to converse in English. * Able to use a computer or mobile device with internet access. * Capable of providing informed consent.
Exclusion criteria
* Current use of antidepressants, antipsychotics, or mood stabilizers. * Self-reported lifetime diagnosis of bipolar disorder, a psychotic disorder, an eating disorder, or a current substance use disorder. * Major life trauma, such as recent bereavement or job loss, within the preceding 3 months. * Current participation in an intervention targeting diet. * Severe food allergies, intolerances, or aversions. * Unwilling to accept a Mediterranean-style diet. * Current daily or regular use of over-the-counter or prescription probiotic/prebiotic supplements. * Systemic oral or intravenous antibiotic use within 30 days before the study. * Self-reported chronic gastrointestinal disorder, including inflammatory bowel disease, irritable bowel syndrome, or celiac disease. * Self-reported history of significant gastrointestinal surgery, such as gastric bypass or bowel resection. * Self-reported systemic autoimmune disease or active chronic infectious disease. * Currently pregnant or lactating, or planning pregnancy during the study.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Depressive Symptoms Assessed by the Center for Epidemiologic Studies Depression Scale (CES-D) | Baseline to Week 8 | Depressive symptoms will be assessed using the Center for Epidemiologic Studies Depression Scale (CES-D). The CES-D is a 20-item self-report measure with a total score ranging from 0 to 60. Higher scores indicate greater severity of depressive symptoms (i.e., a worse outcome). Change in CES-D score from baseline will be compared between the dietary education intervention and befriending control groups. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Depressive Symptoms Assessed by the Patient Health Questionnaire-9 (PHQ-9) | Baseline through Week 8 | Depressive symptoms will be assessed using the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 consists of 9 items and has a total score ranging from 0 to 27. Higher scores indicate greater severity of depressive symptoms (i.e., a worse outcome). |
| Change in Insomnia Symptoms Assessed by the Insomnia Severity Index (ISI) | Baseline through Week 8 | Insomnia symptoms will be assessed using the Insomnia Severity Index (ISI). The ISI consists of 7 items and has a total score ranging from 0 to 28. Higher scores indicate greater severity of insomnia symptoms (i.e., a worse outcome). |
| Change in Anxiety Symptoms Assessed by the Beck Anxiety Inventory (BAI) | Baseline through Week 8 | Anxiety symptoms will be assessed using the Beck Anxiety Inventory (BAI). The BAI consists of 21 items and has a total score ranging from 0 to 63. Higher scores indicate greater severity of anxiety symptoms (i.e., a worse outcome). |
| Change in Autistic Traits Assessed by the Autism-Spectrum Quotient (AQ) | Baseline through Week 8 | Autistic traits will be assessed using the Autism-Spectrum Quotient (AQ). The AQ consists of 50 items and has a total score ranging from 0 to 50 using the standard binary scoring method. Higher scores indicate a greater level of autistic traits. |
| Change in Mediterranean Diet Adherence Assessed by the Mediterranean Diet Adherence Screener (MEDAS) | Baseline through Week 8 | Adherence to a Mediterranean dietary pattern will be assessed using the Mediterranean Diet Adherence Screener (MEDAS). The MEDAS consists of 14 items and has a total score ranging from 0 to 14. Higher scores indicate greater adherence to a Mediterranean dietary pattern (i.e., a better outcome). |
Countries
Singapore
Contacts
CONTACTJiangbo Ying
Outcome results
None listed