To our knowledge, ours is the first study to examine a wide range of maternal conditions, and health services utilization and cost, in the year before and two years after the birth of a child subsequently diagnosed with ADHD. We found that mothers of children with ADHD were more likely to be diagnosed with a number of medical and mental health problems, covering a wide range of etiologies and organ systems compared with mothers of children without ADHD or mothers of children with asthma. We also found that mothers of children with ADHD had higher medical costs and utilization during that time.
The two year period following the birth of the affected child corresponded to the period prior to the child’s initial ADHD diagnosis and thus maternal diagnoses made during this period are much less likely to be the result of the child’s condition, although it is possible that the child manifested certain behaviors prior to the initial ADHD diagnosis and that these affected the mother. However, we found that even during the year before the birth of the child, mothers of children with ADHD were diagnosed more frequently with a wide variety of health conditions and had higher overall health care costs than comparison mothers.
Our finding that the mothers of children with ADHD were more likely to be diagnosed with depression and anxiety disorder is consistent with that of Lesesne et al., who estimated that children of mothers with activity-limiting mental health conditions were about 4 times more likely to have been identified by a health provider as having ADHD (by parental report).27
The latter study, however, was based on self-report and could not address the temporal order of the maternal health condition and the child’s ADHD. More consistent with our methodology (though based on parent surveys), Whitaker et al. found that maternal health conditions (broadly defined as mental health, substance use and domestic violence) in the year after delivery were associated with child behavioral problems at three years of age, including inattention/hyperactivity.33
There are a number of ways in which to view the relationship between maternal medical conditions and health care utilization and having a child with ADHD. (1) The mother may be genetically predisposed to ADHD and conditions relating to it, which lead to higher utilization of services, and which are inherited by the child and manifest as ADHD in the child; (2) The mother’s general health status may adversely affect the developing fetus and predispose the child to ADHD; (3) The mother’s medical conditions and psychopathology may, after the birth of the child, contribute to adverse family environment which in turn is related to a child developing ADHD; (4) The mother’s medical conditions and utilization may be related to her increased propensity to seek services and diagnoses, both for herself her child.
Disentangling these putative causal pathways is extremely challenging. The genetic basis for ADHD is well established3,4
, and a number of studies suggest that pregnancy and delivery complications, maternal stress during pregnancy, and chronic exposure of the fetus to alcohol or tobacco, may be risk factors for ADHD.18
In addition, there is evidence that adverse family-environment is also predictive of ADHD in children.14,34
Few studies have investigated the factors that influence referrals for ADHD evaluation, including maternal propensity to use services. Schneider and Eisenberg note that the inherent subjectivity of the DSM-IV criteria for diagnosing ADHD allows for a range of individuals to influence the diagnosis process.29
Based on a survey of practicing physicians, Sax and Kautz estimated that the diagnosis of ADHD is most often initially suggested by teachers (46% of the time), followed by parents (30% of the time), and least often by a primary care physician or MD consultant (14% of the time).35
There is evidence - confirmed in the current study - that non-white Americans are less likely to be diagnosed with, and treated for, ADHD.29,36,37
Race may, in part, be a proxy for cultural variations in help-seeking patterns.38,39
In our study, mothers of children with ADHD were more likely to be diagnosed with both psychiatric and non-psychiatric conditions. Although conditions such as depression are known to be independent risk factors for a number of medical illnesses40
, it is also possible that mothers of children with ADHD may have a higher propensity to use services and seek medical attention — both for themselves and for their children. Our results of increased health care costs and utilization among mothers of children with ADHD in comparison to mothers of children with asthma lend support to this hypothesis. These results suggest that explanatory models of childhood ADHD (or the diagnosing of childhood ADHD) should take into account maternal health, health-seeking behavior, and propensity to use services.
We did not independently assess the validity of the ADHD diagnoses made by providers; thus, there may be some misclassification. Nevertheless, the children with ADHD were considered by the health system to have ADHD. Diagnosis of ADHD is likely to drive physician prescribing patterns and behavioral treatments and thus be important from the health system perspective. Because women can be diagnosed with multiple conditions and these diagnoses can be repeated in different time periods, the results from one diagnosis cluster to another, or one time period to another, are not independent of each other. We did not adjust for multiple comparisons (a procedure we view as problematic41
) and, given the large number of conditions we analyzed, there is an increased possibility that some differences were significant due to random variation. However, that mothers of children with ADHD were more commonly diagnosed with nearly every condition (whether significantly or not) is unlikely to be due to chance alone. Because of limitations in the availability of historical data, the study population was limited to mothers of children diagnosed with ADHD between 2 and 11 years of age. Our results cannot strictly be applied to mothers of children diagnosed with ADHD at later ages.
Compared to mothers of children without ADHD, and to mothers of children with asthma, the mothers of children with ADHD are more likely to be diagnosed with a number of medical and mental health conditions, and have higher health care costs and utilization in the year before, and the two years after, the birth of a child subsequently diagnosed with ADHD. The reasons for these differences are likely explained by a combination of biological, environmental, and psychosocial factors (including propensity to use services and seek diagnoses), and future studies are needed to clarify their contributions.