BOSTON — A diagnosis of maternal depression any time between 1 year before and 9 years after giving birth is a risk factor for attention-deficit/hyperactivity disorder in school-age children, according to a study presented at a meeting of the Society for Research in Child Development.
In addition, the likelihood of an attention-deficit/hyperactivity disorder (ADHD) diagnosis in children is directly related to the chronicity of depression in the mother, said Anne Guevremont, M.Ed., a research fellow at the Manitoba Centre for Health Policy at the University of Manitoba, Winnipeg
Although previous studies have linked maternal depression to ADHD in children, none have specifically investigated whether and to what degree the timing of maternal depression has an impact on the relationship, Ms. Guevremont said.
Through computerized health care user files from the Manitoba health department, Ms. Guevremont and senior researcher Marni Brownell, Ph.D., reviewed data on 12,323 children born between April 1993 and March 1994 whose mothers were living in Manitoba the year before the child's birth and for whom follow-up information was available until the child was 7-9 years old.
The investigators ascertained the presence of maternal depression by hospital or physician claims for this diagnosis and categorized the depression into one of five groups according to the child's age at the time of the mother's diagnosis: within 1 year before birth, within 1 year after birth, between 1 and 3 years old, 4-6 years old, and 7-9 years old.
Approximately 36% of the mothers in the study had a diagnosis of depression during at least one time period, Ms. Guevremont reported in a poster presentation. Among the children, approximately 5% had a physician diagnosis of ADHD when they were 7-9 years old, she said.
With respect to chronicity, the investigators considered each time period in which a mother had a diagnosis of depression and counted the total number of years that the mother had the diagnosis outside of that time period, according to Ms. Guevremont. “Approximately 16% of the mothers had a depression diagnosis in 1 year only, while 8% of the mothers received a depression diagnosis in 2 years and 12% in 3 or more years,” she said.
In analyses of the effect of the timing and chronicity of maternal depression on child ADHD, children with depressed mothers were approximately 1.5-2 times more likely to have an ADHD diagnosis than children of nondepressed mothers, said Ms. Guevremont, noting that the odds ratio was highest, at 2.18, for mothers diagnosed with depression in the year before the child's birth. This finding “confirms the need to look for maternal depression at every stage of motherhood, including the prenatal period,” she said. “The prenatal period is an excellent time to screen for depression, as the vast majority of mothers seek prenatal care before their child's birth.”
In addition, the chronicity of depression was significant in each model, and the odds of a child being diagnosed with ADHD were higher for each additional year a mother was diagnosed with depression, regardless of the timing of the diagnosis, said Ms. Guevremont. The interaction between chronicity and timing was significant among children whose mothers were diagnosed in the year before birth, in the year after birth, or when the child was between 1 and 3. Children whose mothers were diagnosed during these periods and who had longer durations of depression were most vulnerable to an ADHD diagnosis, the results showed.
“Clearly, the number of years with a depression diagnosis is particularly important, and should be taken into consideration by clinicians caring for both mothers and their children,” Ms. Guevremont said. “The earlier depressed mothers are recognized and treated, the better for the health of both the mother and her children. Intervention at multiple time periods is possible and needed.” For example, in addition to prenatal screening, “another opportunity for screening is when mothers seek physicians for the children's behavior problems,” she said.
The study is limited by the potential for underreporting of both maternal depression and child ADHD, Ms. Guevremont noted. “Some physicians may not know a mother is depressed and therefore would not diagnose the condition if symptoms are not reported,” she stated.