While psychology research has previously shown that elderly people living alone are more at risk for depression and other mental health conditions, a new Finnish study finds that younger working-age adults who live by themselves are 80 percent more likely to develop depression compared with people living in families. 

Investigators surveyed 3,471 men and women ages 30 to 65 in 2000 and asked whether they lived alone or with others, as well as other information about their lifestyle like social support, work climate, education, income, employment status, housing condition, smoking habits, alcohol use and physical activity levels.

The findings show that people who lived alone bought 80 percent more anti-depressants during the seven-year follow-up period ,and that a quarter of participants living alone filled an antidepressant prescription during the study period, compared to just 16 percent of those who lived with others like spouses, family or roommates.

Researchers suggest that the link between living alone and depression could be explained by several types of psychosocial and material disadvantages of single people.

Adverse socioeconomic factors, particularly for women, partly explained the relationship between depression and living alone and psychosocial factors and a lack of social support were important explanatory factors, particularly for men. 

“Health behaviors had only a marginal contribution to the association between living alone and antidepressant use among men and women, with the exception of heavy alcohol use in men,” the authors wrote.

The latest findings that urban living, poor housing conditions, and rental living contributed to the association between living alone and antidepressant use are supported by previous work that “single people suffer from ill health due to material and socioeconomic disadvantages,” particularly for women the authors wrote.

Lead author Dr. Laura Pulkki-Raback of the Finnish Institute of Occupational Health said that the findings suggest that there is there is a significantly higher risk for mental health problems in people living alone. 

"This kind of study usually underestimates risk because the people who are at the most risk tend to be the people who are least likely to complete the follow up. We were also not able to judge how common untreated depression was," Pulkki-Raback said, according to BBC.

Researchers are unsure whether depression or living alone comes first.  They explained that people living alone possessed more cynical attitudes, and cynics may have ended up living alone because they are difficult for others to deal with.

Experts say that living with other people offers individuals emotion support, feelings of social integration, and other factors that protect against mental health problems, whereas living alone is could be associated with feelings of isolation, lack of social integration and trust.

"Loneliness and isolation results in people having fewer outlets to talk about how they are feeling, which is something that we know can really help to manage and recover from a mental health problem,” Beth Murphy, head of information at a UK mental health charity Mind, told BBC.

"It is therefore essential that people who live alone are given the most appropriate treatment such as talking therapies, which provide safe, supportive environments to discuss and work through problems, rather than simply being left to rely solely on antidepressants," Murphy concluded.