It has long been known that depression and other mood disorders seem to run in families. At least one study has attempted to gain a measurable understanding of the way depression is passed down between generations.
In an ambitious and forward thinking move the Swedish government has kept a multigenerational register of all people born in that country since 1932 and is recording vital information about families. Since 1987 the government has also kept a record of all hospital discharges for depression in Sweden.
Using this recorded information, researchers at the Karolinska Institute conducted a study to calculate familial risks of depression between 1987 and 2004.
Not only did they discover an increased risk of depression among individuals whose parents experienced the disorder, but they were also able to find age specific incidence rates and compare between those with a family history and those without.
Individuals with one depressed parent had about three times the likelihood of experiencing depression than those whose parents did not have the illness. Further, men with two depressed parents were five times more likely to be hospitalized for depression than men with no family history and women with two depressed parents increased their risk by seven times.
The highest risk was for either males or females between the ages of 15 and 29 with two depressed parents. Among this group, males had eight times the risk of being hospitalized for depression and females had 11 times greater risk than those with no family history.
Researchers also examined risk levels based on whether an individual’s mother or father had been depressed and found some interesting results. Among men, the risk remained fairly similar regardless of whether their mother or father had experienced depression. However, among women the risk was greater if the mother was depressed than the father.
Risk levels according to age were also calculated. Among individuals with no family history of depression incidence rates rose gradually with increasing age – and for those with a family history there was a jump between the ages of 15 and 20 and then again between ages 40 and 44 and after age 60.
Although this study makes it clear there is a strong family link in depression and quantifies this link for gender and age, it does not explain the reason for family impact on depression risk.
We know depression does have a genetic factor and scientists have already begun identifying some of the specific genes involved in depression, but we have yet to learn exactly what role the genetics play in terms of heritability.
Environmental factors likely also play a role in the development of depression and one scientist involved in the Swedish study noted children could learn depressive strategies from the behaviour of their depressed parents. These could include negative patterns of thinking or beliefs or maladaptive behaviours.
More research is needed before we can fully understand the way depression works and how it is passed down through generations of family.
In the meantime, there are effective treatments available for depression regardless of your family history. If you think you are depressed, speak with your doctor about treatment options or ask for a referral to a psychiatrist. You don’t need to continue suffering.