Children of mothers experiencing depressive symptoms are more at risk, as adolescents, of experiencing suicidal thoughts and attempting suicide.
New research suggests that this link may be explained by loneliness, potentially opening new ways for youth suicide prevention.
The study - by the universities of Exeter, Montréal, Laval and McGill - used data from more than 1,600 families from the Québec Longitudinal Study of Child Development, a representative sample of new-borns in Quebec followed from birth to 20 years of age.
Mothers were asked about depressive symptoms (such as sadness and losing interest in formerly pleasurable activities) at regular intervals while their children were aged five months to seven years.
The resulting information gave a measure of depressive symptoms - not a clinical diagnosis of depression.
Adolescents completed self-reports about suicidal thoughts and attempts at age 13-20 years.
Children of mothers with higher levels of depressive symptoms were approximately 15% more likely to have suicidal thoughts and/or attempt suicide as adolescents compared to children of mothers with lower levels of depressive symptoms.
"We cannot say to what extent this association is due to childhood experiences, genetics or other factors," said lead author Dr Lamprini Psychogiou, of the University of Exeter.
"But identifying some of the mechanisms explaining why those children are at increased suicide risk later in life is essential to understand how to prevent suicide among children of mothers with depression."
To this aim, the authors investigated whether feeling of loneliness and social withdrawal reported by the adolescents at age 10-13 years may account for this association.
"We found that maternal depressive symptoms in the early years of a child's life are associated with those children self-reporting elevated levels of loneliness as adolescents, which, in turn, is associated with suicidality," said Dr Psychogiou.
"We do know that social relationships in general, and peer relationships in particular, are really important for adolescents. Feeling lonely in early adolescence may influence how one perceives life as being worth living.
"Our findings are important because they suggest that interventions targeting loneliness in young adolescence for children of mothers with depression, may potentially help reduce their risk of suicidal thoughts or suicide attempts later in life.
"It's important to note that our study did not examine cause and effect."
Further studies are needed to quantify to what extent reducing feeling of loneliness translates into a decrease in suicide risk for those adolescents.
The paper, published in the journal Development and Psychopathology, is entitled: " The mediating role of adolescents' loneliness and social withdrawal in the association between maternal depressive symptoms and suicidality in adolescence: A 20-year population-based study."
Development and Psychopathology