RESEARCH ARTICLE Relationship of the Perceived Social and Physical Environment with Mental Health- Related Quality of Life in Middle-Aged and Older Adults: Mediating Effects of Physical Activity

Background Mental health conditions are among the leading non-fatal diseases in middle-aged and older adults in Australia. Proximal and distal social environmental factors and physical envi-ronmental factors have been associated with mental health, but the underlying mechanisms explaining these associations remain unclear. The study objective was to examine the con-tribution of different types of physical activity in mediating the relationship of social and physical environmental factors with mental health-related quality of life in middle-aged and older adults. Methods Baseline data from the Wellbeing, Eating and Exercise for a Long Life (WELL) study were used. WELL is a prospective cohort study, conducted in Victoria, Australia. Baseline data collection took place in 2010. In total, 3,965 middle-aged and older adults (55–65 years, 47.4 % males) completed the SF-36 Health Survey, the International Physical Activity Ques-tionnaire, and a questionnaire on socio-demographic, social and physical environmental at