It is already known that a mother's depression can have a negative impact on the behaviour of toddlers, however a new study has found that a father's depression can also have a major impact.

Previous studies in this area have tended to focus on mothers with postnatal depression and the effect this can have on a child's behaviour during their early years.

However, according to US researchers, ‘fathers' emotions affect their children and new fathers should be screened and treated for postpartum (postnatal) depression, just as we do for new mothers'.

They looked at almost 200 couples with three-year-old children. All had previously participated in a study about depression around the time of the child's birth. For this study, both members of the couple regularly filled in questionnaires about depression, their relationship with their partner and their child's internalising and externalising behaviours.

Internalising behaviours included anxiety and sadness, while externalising behaviours included hitting and acting out.

The study found that both a mother and father's depression levels were associated with children's internalising and externalising behaviours. In other words, if either the mother or father was depressed, this had an effect on a toddler's behaviour.

Furthermore, the study found that having a depressed parent contributed more to a child's bad behaviour than having parents who fought with each other.

The researchers noted that when parents are depressed, they may not make as much eye contact with their children or smile as much compared to if they were not depressed. If a parent becomes disengaged from their child, the child may subsequently have problems dealing with attachments and emotions.

"Depression affects the way people express emotions, and it can cause their behavior to change. Early intervention for both mothers and fathers is the key. If we can catch parents with depression earlier and treat them, then there won't be a continuation of symptoms, and maybe even as importantly, their child won't be affected by a parent with depression," commented the study's lead author, Dr Sheehan Fisher, of Northwestern University.

Details of these findings are published in the journal, Couple and Family Psychology: Research and Practice.

For more information on depression, see our Depression Clinic here