Effectiveness of Walking Exercise in Improving Depression in Older Adults With Major Depressive Disorder, A Pilot Study

BDI is a 21-item self-reporting questionnaire for evaluation of the severity of depression in both normal and psychiatric populations. Each item includes four statements numbered from 0 to 3, with a higher number indicating more severe depressive symptoms. Participants will be asked to circle the statement that can best describe them in a paper-pencil based manner. The BDI score interpretation is: less than 10: no or minimal depression, 10-18: mild-to-moderate depression, 19-29: moderate-to-severe depression, over 30: severe depression

The use of antidepressants such as most commonly prescribed Prozac (fluoxetine), Zoloft (sertraline), Lexapro (escitalopram), Paxil (paroxetine), Celexa (citalopram), or selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, with detailed usage information (e.g., drug name, type, dosage, and frequency of dosage) will be recorded. Subjects will be asked to provide the dosage, frequency of the daily antidepressant usage. The duration between the first interview of this study and the first diagnosis of MDD will also be recorded.

Generalized Anxiety Disorder 7-item (GAD-7) scale will be used to measure the anxiety level of the subjects. The GAD-7 is a reliable and valid measure of anxiety severity and its brevity make the GAD-7 a useful clinical and research tool. Higher score indicates more severe level of anxiety.

The Pittsburgh Sleep Quality Index (PSQI) is a standardized instrument to estimate sleep quantity and quality. The PSQI has been commonly used to distinguish people with primary insomnia from normal sleepers. The Chinese version of PSQI has been validated to have a satisfactory Cronbach's alpha of 0.82-0.83 and test-retest reliability of 0.85 among Hong Kong Chinese older adults.

SF-12 was originally developed for medical outcomes study, and it is one of the most widely used instruments for assessing health-related quality of life. SF-12 covers the same eight domains as the SF-36 form, which assesses physical functioning, emotional and mental health, body pain, general health, social functioning and vitality, with a higher score indicating a better quality of life.

The participant's maximal oxygen consumption will be measured at baseline, 12 weeks intervention to evaluate the participants' cardiovascular fitness by VO2max test using a COSMED Quark Series telemetric gas analysis system.

The participant will be asked to sit quietly for 20 minutes for resting HR recording. The resting HR will be measured by Optical heart rate sensor (Polar OH1).

Body weight and height of the subject will be measured by a validated scale (A&D, UC-321) to the nearest 0.1kg and stadiometer (SECA, CE-0123) to the nearest 0.1cm. The BMI will be calculated as BMI = kg/m2.

The Chinese version of IPAQ is one of the most reliable self-report measures of physical activity for older adults, with intraclass correlation coefficients ranging from 0.81 to 0.89. Three categories of physical activities are classified in IPAQ: Low, moderate and high. Continuous score is also suggested to be expressed as MET-min per week, which can be calculated using the data from IPAQ.