New research has discovered that if fathers get depressed (as new mothers often do), it can be bad for their children's language development. Specifically, two-year-olds who were studied have a much smaller vocabulary if their fathers have depression than if their mothers do.
The depression we were already aware of, from Mom, is called Postnatal Depression and it is widely recognized for it's link to emotional difficulties in their children. To explore the effects of depression from the father's side, a team led by pediatric psychologist James Paulson at the Eastern Virginia Medical School in Norfolk surveyed about 5000 families enrolled in the Early Childhood Longitudinal Study, which is funded by the US Department of Education. The study records symptoms of depression in parents.
When the children were 9 months old, 14 per cent of the mothers and 10 per cent of the fathers were clinically depressed - about twice the rates for the general population. To anyone who can remember having a new baby in the house, you'll recall the lack of sleep and the stress events (financial and otherwise) which may be behind the depression.
The surprise for researchers came when they looked at whether this affected what proportion of 50 common words the children were using at 2 years of age. While depression from Mom had no effect on vocabulary, 9-month-olds with depressed dads went on to use fewer words at age 2 than those whose fathers were fine.
Other studies have found that maternal depression can also slow speech development, but Paulson is the first to suggest that paternal depression has the bigger effect. One explanation, says the main author, is that depression in mothers did not reduce the time they spent reading to their 9-month-old baby, but depressed dads read significantly less often than those who felt fine. The lesson is obviously that Dad should read to the new baby, no matter how he feels at any given time.
This material was presented at the American Psychiatric Association meeting in Washington DC, which I attended personally.