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

The Hamilton Depression Rating Scale-17 (HAMD-17), developed by Hamilton in 1960, is a widely used clinical rating scale consisting of 17 items that evaluate various depressive symptoms, including mood, suicidal thoughts, sleep disturbances, loss of interest, psychomotor changes, anxiety, gastrointestinal and somatic symptoms, sexual dysfunction, and weight loss. Scored on a scale of 0 to 4 (with some items possibly using a 0 to 2 scale), the total score reflects the severity of depressive symptoms and is used for diagnosing depression, planning tailored treatment, monitoring treatment effectiveness, and conducting research on depression treatment efficacy.

The Chinese version of the Perceived Deficits Questionnaire for Depression (PDQ-D) has been validated for reliability and validity among patients with depression in China. The PDQ-D comprises 20 items, yielding a total score that ranges from 0 to 80. Higher scores indicate a greater severity of self-perceived cognitive symptoms. Demonstrating good reliability and validity, the questionnaire assesses patients' cognitive function across four dimensions: attention/concentration, prospective memory, retrospective memory, and planning and organization.

Cognitive function will be also assessed using the CBCT, which has been validated in a large-scale study of schizophrenia patients and has shown good internal consistency and test-retest reliability. Also, additional studies in MDD population provide further evidence of its reliability and validity supporting the robustness of this scale for assessing cognitive function in these clinical groups.

The Stroop Color Word Test (SCWT) was developed by Professor Stroop in 1935 to evaluate subjects' executive functions. The test is a measure of selective attention and the degree of inhibition of irrelevant information in executive functioning. It consists of three main parts: reading words (Stroop-w), color naming (Stroop-c), and color-word interference (Stroop-cw), which require subjects to accurately and quickly read the words or the colors, respectively, as required.

Hopkins Verbal Learning Test-Revised (HVLT-R) is a widely used neuropsychological assessment tool designed to evaluate verbal memory and cognitive function. Developed by J. Brandt and Benedict in 2001, the HVLT-R consists of a list of 12 nouns divided into three semantic categories (e.g., dwelling places, four-legged animals, and precious stones), with four words per category. The assessment involves three learning trials, where participants are presented with the list of words and are asked to recall as many words as possible immediately after each presentation. Additionally, there is a delayed recall trial, where participants are asked to recall the words after a delay of 20-25 minutes. The scoring principle is based on the number of correctly recalled words during each learning trial and the delayed recall trial. The total score for the three learning trials and the delayed recall trial is calculated as well.

The Generalized Anxiety Disorder-7 is a standardized assessment tool developed by Spitzer et al. in 2006. It is a 7-item questionnaire designed to evaluate the severity of anxiety symptoms over the past two weeks. The scale covers various aspects of anxiety, including feelings of tension, worry, irritability, and difficulty relaxing. Each item is rated on a 4-point scale, ranging from 0 (not at all) to 3 (nearly every day), with total scores ranging from 0 to 21. Higher scores indicate more severe anxiety symptoms. The GAD-7 is primarily used as a screening and assessment tool in clinical and research settings, aiding clinicians in identifying and quantifying anxiety symptoms, monitoring changes over time, and evaluating treatment effectiveness. It is a simple, reliable, and valid instrument that can be easily administered and scored, making it a valuable addition to the clinical assessment of anxiety disorders.

The Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR-16), a rigorous and systematic self-assessment scale developed by Rush et al. in 2003 with subsequent refinements, is a widely recognized tool for quickly gauging depressive symptoms over the past week. It comprises 16 items covering various dimensions of depression, including mood, sleep, appetite, energy levels, concentration, self-esteem, suicidal ideation, and daily functioning, each rated on a 4-point scale (0-3). The scale assesses the severity and frequency of symptoms, with higher scores indicating more severe depression. The QIDS-SR16 serves multiple purposes: it aids in screening and assessing depressive symptoms in clinical settings, allows individuals to monitor their depressive state over time, serves as a research tool in clinical studies evaluating treatment effectiveness, and provides valuable information that can support the diagnostic process when combined with clinical interviews.

The PSQI, or Pittsburgh Sleep Quality Inventory, was developed by Buysse et al. in 1989. It is a widely used and standardized self-report questionnaire designed to assess sleep quality over the past month. The PSQI consists of 19 self-rated items and 5 additional items for bed partner or roommate ratings (though only 18 of the self-rated items are scored). The assessment covers seven components: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Each component is scored on a 0-to-3 scale, with the total PSQI score ranging from 0 to 21. Higher scores indicate poorer sleep quality, with a total score of 5 or less indicating good sleep quality, 6-10 indicating fair sleep quality, 11-15 indicating poor sleep quality, and 16 or more indicating very poor sleep quality. The PSQI serves multiple purposes, including clinical diagnosis of sleep disorders, research on sleep quality, and eval

The Young Mania Rating Scale (YMRS), developed by R.C. Young and colleagues in 1978, is a clinician-administered rating scale designed to assess the severity of manic symptoms over the past week. It comprises 11 items that evaluate various aspects of mania, including elevated mood, increased activity and energy, sexual interest, sleep pattern, irritability, speech, language-thought disorders, content of thought, aggressive or destructive behavior, appearance, and insight. The scoring system varies across items, with some rated on a 0-4 scale and others on a 0-8 scale. The total score is obtained by summing the ratings of all items, providing a quantitative measure of manic severity. Higher scores indicate more severe manic symptoms. The YMRS is primarily used in clinical and research settings for the assessment of manic states.

Asberg Side-Effect Rating Scale for Antidepressants (SERS) is a rating scale developed by Swedish psychiatrist M. Asberg in 1970. It is specifically designed to evaluate the adverse effects experienced by individuals following the administration of antidepressant medications. The scale contains 14 items that assess a wide range of symptoms, including physical fatigue, dizziness, headache, sleep disturbance, orthostatic hypotension, palpitations, tremors, sweating, dry mouth, constipation, urinary difficulties, somnolence, sexual dysfunction, and other symptoms. Each item is rated on a 4-point scale ranging from 0 (absent) to 3 (severe), allowing for a comprehensive quantification of the severity of side effects. The total score, calculated by summing the ratings of all items, provides an overall measure of antidepressant-related adverse effects. The SERS is primarily used in clinical and research settings to aid in the identification, monitoring, and documentation of side effects.

The Q-LES-Q-SF, developed by Endicott et al. in 1995, consists of 16 items that assess an individual's subjective satisfaction with their quality of life over the past 7 days. The first 14 items reflect various aspects of quality of life, including physical and mental health, mood, work, household responsibilities, social relationships, family relationships, leisure activities, daily living skills, sexual functioning, financial status, living environment, mobility, hobbies, and overall subjective satisfaction with physical and mental health. Items 15 and 16 assess daily medical care and overall life satisfaction. Each item is rated on a scale from 1 to 5, with higher scores indicating better quality of life. The overall score for the Q-LES-Q-SF is derived from the sum of the scores from items 1 to 14.

The SDS evaluates the impact of depression on a patient's work, social life, and family responsibilities. The total score ranges from 0 to 30, with higher scores indicating greater functional impairment . The SDS has demonstrated strong reliability and validity in depressed populations.

Originally developed by Hamilton in 1959, the HAMA is a classic clinician-administered questionnaire assessing both somatic and psychic anxiety severity. The 14-item instrument captures psychic anxiety (items 1-6, 14) and somatic anxiety (items 7-13). Each item is rated on a 5-point Likert scale from 0 (absent) to 4 (very severe), with higher total scores indicating more severe clinical anxiety. The construct validity and reliability of the Chinese HAMA adaptation have been rigorously established in domestic psychometric studies.

The Insomnia Severity Index (ISI) is a standardized tool used to assess the severity of insomnia symptoms and their impact on daily life. It consists of 7 items that encompass difficulties in falling asleep, sleep maintenance, early awakening, satisfaction with sleep, distress caused by symptoms, impairment of daily functioning, and concern about insomnia. Each item is rated on a scale from 0 to 4, with a total score ranging from 0 to 28. A higher score indicates more severe insomnia issues.

The Color Trails Test (CTT) (Maj, D'Elia, Satz, Janssen, Zaudig, Uchiyama et al., 1993; D'Elia, Satz, Uchiyama \& White, 1996) is a language-free version of the Trail Making Test (TMT) that was developed to allow for broader cross-cultural application to measure sustained attention and divided attention in adults.The CTT is comprised of two tasks: CTT-1 must be administered first and requires the respondent to connect circles in an ascending numbered sequence (1-25).

CTT-2 must follow the CTT1 and requires the respondent to connect numbers in an ascending sequence while alternating between pink and yellow colors. Numbers are presented twice, once in pink and once in yellow, so the client must ignore the distracter item (e.g. start at pink 1, avoid pink 2 to select yellow 2, avoid yellow 3 to select pink 3, etc.).