However, the team was surprised to see that there is a 'solid relationship' between the two.
"We thought that once we statistically accounted for factors that could clearly contribute to depression - things like employment status and crowding - we would see any link vanish," said Shenassa, the lead author of the study and an associate professor in the Department of Community Health at Brown.
"But the opposite was true. We found a solid association between depression and living in a damp, mouldy home," he added.
Shenassa noted the study, an analysis of data from nearly 6,000 European adults, does not prove that mouldy homes cause depression. The study wasn't designed to draw that direct conclusion.
However, Shenassa's team did find a connection, one likely driven by two factors. One factor is a perceived lack of control over the housing environment. The other are mould-related health problems such as wheezing, fatigue and a cold or throat illness.
"Physical health, and perceptions of control, are linked with an elevated risk for depression and that makes sense. If you are sick from mould, and feel you can't get rid of it, it may affect your mental health," Shenassa said.
The study was a statistical analysis of data from the Large Analysis and Review of European Housing and Health Status (LARES), a survey on housing, health and place of residence conducted in 2002 and 2003 by the World Health Organization (WHO).
To conduct the survey, WHO interviewers visited thousands of homes in eight European cities and asked residents a series of questions, including if they had depressive symptoms such as decreased appetite, low self-esteem, and sleep disturbances. WHO interviewers also made visual checks of each household, looking for spots on walls and ceilings that indicate mould.
Shenassa's team analyzed LARES data from 5,882 adults in 2,982 households.
"What the study makes clear is the importance of housing as indicator of health, including mental health. Healthy homes can promote healthy lives," Shenassa said.
The study is published in the American Journal of Public Health.