Salivary cortisol levels are used to study physiologic responses to stress. Dr. Stowe presented a study that examined changes in salivary cortisol among infants with depressed mothers.
Nineteen six-month-old infants of mothers with a history of major depression were compared with eleven infants of mothers with no history of major depression or other Axis I disorders.
All mothers completed self-rating scales to assess depression, as well as a questionnaire on stressful life events. Two more clinician-rated scales were also used.
The infants were exposed to a series of tasks that included a baseline rest period, habituation task, sound burst exposure, arm restraint task, a videotaped interaction with the mother, and a neurological screen. Saliva samples from the infant were collected six times throughout the task sequence.
Although researchers found no differences in baseline salivary cortisol levels between the two groups, infants whose mothers were depressed had higher responses to stress as measured by salivary cortisol.
Dr. Stowe said that it was possible to identify the babies of depressed mothers using only the differences in salivary cortisol levels.
Dr. Stowe believes that maternal depression can alter the balance of brain chemicals in the baby to at least to six months of age, resulting in a hyper-responsivity to stress. This is clinically important when discussing medication with the mother, because mothers who stop antidepressant medication to protect their infants may in fact be hurting them in other ways.
Dr. Stowe stressed that treatment issues have an impact on both baby and mother. His work suggests that as the mother's illness worsens, her baby may be subjected to extra stress.