Studies: Smoking, Childhood Relationships Can Increase Clinical Depression

Studies Find Two New Links to Depression

One expert, Dr. Gregory Simon, a psychiatrist and mental health researcher at the Group Health institute in Seattle, said that the study provides a valuable insight into the relationship between early life development and long-term risk for common mental health and substance use problems. He agreed with Waldinger and his colleagues that the study suggests there is a relationship between depression and childhood sibling relationships but the direction of the relationship couldn't be determined.

"It is certainly possible that poor relationships with siblings during childhood have significant and enduring negative effects on mental health," Simon said. "It is also possible, however, that poor relationships with siblings are one of the early signs of depressive illness."

Another long-term study, suggests that smoking may also be a link to depression. While research has often suggests that drugs may be a cause of depression, this study found a direct link between cigarette smoking and depression.

The study from the Department of Public Health at the University of Helsinki consisted of 4,000 male and 5,000 female finnish twins, whose health and health behavior were monitored over a 15 year period suggests that persistant chronic cigarette smoking predicts the development of depressive symptoms.

The study, published in Psychological Medicine, also found when adjusting for other factors associated with depression, the elevated risk due to persistant smoking remained significant only among men.

There was also evidence of a short term increased risk of depression among smokers who had quit. Those who quit and remained off cigarettes in the long run did not have an increased risk compared with never smokers. Dr. Tellervo Korhonen from the University of Helsinki, lead author of the study, said in a statement to Reuters Health that this may reflect a relatively long recovery process from the effects of cigarette smoking.

"When people start smoking, the immediate effects of nicotine in the brain are rewarding and pleasurable," Korhonen explained. "This suggests self-medication, where a person who has mood problems seeks relief via cigarette."

Because addiction to nicotine is as strong as an addiction to heroin, abstinence is difficult.

"Smokers who are vulnerable to depression may need specific pharmacological treatment and behavioral support to overcome the earlier phase of abstinence," Korhonen said. After that, "their chances to quit successfully improve."