Efficacy of Bright Light Therapy on Cognitive Impairment in Major Depressive Disorder and Its Neuroimaging Mechanisms: Protocol for a Randomised Controlled Trial

The inclusion and exclusion criteria for MDD patients. 1、Inclusion Criteria: 1. MDD diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-Ⅳ), first episode or recurrence, confirmed by an experienced psychiatrist using the Mini International Neuropsychiatric Interview. 2. Age between 18 and 60 years; and gender no-limited; 3. The severity of MDD symptoms must be ≥14 scores on the HAMD-17; 4. With CI currently, defined as a total score of \<70 on the SC; 5. A SSRI monotherapy at stable dosages for at least 4 weeks; or medication-free status; 6. Education level above primary school, able to understand and cooperate in completing the study procedures; 7. Voluntarily participating in this study and sign the informed consent before enrollment. 2、Exclusion Criteria: 1. Current or past diagnosis of any disorder other than MDD according to DSM-Ⅳ criteria; 2. The scores on the Young Mania Rating Scale (YMRS) are\>8; 3. The participants who have undergone other intervention in addition to SSRIs whinin the past 6 months or now, or who plan to do that in 1 month; 4. The participants with strong self-blame, self-harm, or suicidal risks (the HAMD-17 suicide item score of ≥3); 5. The participants with severe physical illnesses, including heart failure, renal failure, severe liver dysfunction, hyperthyroidism, or hypothyroidism; Or a history of severe brain trauma or organic brain pathology (e.g., intracerebral hemorrhage, large-area cerebral infarction, encephalitis, epilepsy), as well as neurological diseases; 6. The participants with any degree of retinal pathology, including retinal dystrophy, age-related macular degeneration, diabetic retinopathy, cataracts, glaucoma, or other ocular diseases; 7. The participants with photosensitive conditions, such as systemic lupus erythematosus, porphyria, chronic photodermatitis, solar urticaria, or those currently receiving medications that may increase photosensitivity (e.g., phenothiazines, antimalarials, propranolol, hypericin, stimulants, or chronic treatment with nonsteroidal anti-inflammatory drugs); 8. Pregnant or lactating women; 9. The participants with contraindications to MRI, such as the presence of non-MRI-safe metallic implants or claustrophobia; 10. The participants deem unsuitable for inclusion in this study by the investigator for other reasons. Withdrawal and Termination Criteria： 1. The participants meet one of the exclusion criteria above after enrollment; 2. When the participants' treatment regimen need change; 3. The participants who fail to cooperate or voluntarily withdraw from the study; 4. Due to severe adverse events, the patients are unable to tolerate phototherapy; 5. The participants who fail to adhere to the study protocol intervention for three consecutive days or for a cumulative duration exceeding seven days; 6. Cancellation of the study. The inclusion and exclusion criteria for Health controls 1\. Inclusion criteria 1. Age between 18 and 60 years; and gender no-limited; 2. Without CI currently, defined as a total score of ≤ 70 on the SC; 3. Education level above primary school, able to understand and cooperate in completing the study procedures; 4. Voluntarily participating in this study and sign the informed consent before enrollment. 2.Exclusion criteria 1. Current or past diagnosis of any psychiatric disorders, or history of substance/drug abuse or dependence; 2. Current or past diagnosis of severe somatic diseases, such as heart failure, renal failure, severe liver dysfunction, or hyperthyroidism/hypothyroidism; 3. History of severe traumatic brain injury or organic brain lesions; 4. Pregnant or lactating women; 5. The participants with contraindications to MRI, such as the presence of non-MRI-safe metallic implants or claustrophobia. 6. The participants deem unsuitable for inclusion in this study by the investigator for other reasons.