Campbell and colleagues found that even though most postpartum depressions tend to be brief, they can last as long as two years; even those women whose depressive episode abates are likely to continue to experience more subtle difficulties (Campbell, Cohn, Flanagan, Popper, and Meyers, 1992). These problems eventually are reflected in the mother-infant relationship. In Campbell's study the infants of depressed mothers received less appropriate and less responsive care and more negative and rejecting care than the comparison group at two months. The impact of maternal depression on the infant's development can be seen quite early. Field (1992) found that these infants can develop a “depressed mood style” as early as three months and that this mood state persists over the first year of life if the mother's depression persists. By the end of the first year, this mood has affected both physical growth and scores on the Bayley Scales of Infant Development. There is also some evidence that by 11 to 17 months of age, infants of depressed mothers exhibit reduced activity in the right frontal area of the brain (Dawson, Klinger, Panagiotides, Spieker, and Frey, 1992). This finding raises the possibility that maternal behavior can influence not only an infant's developing psychosocial areas of functioning but also the development of the central nervous system.
Maternal depression is not the only, and perhaps not even the most frequent, risk factor for the development of depression during childhood. For example, other forms of parental psychopathology and child maltreatment, and especially the interactive effects when both risk factors are present, also significantly increase the likelihood that a child will become depressed in middle childhood (Downey and Walker, 1992; Toth, Manly, and Cicchetti, 1992).
The rate of depression rises overall between childhood and adolescence. In a sample of 3,519 8- to 16-year-old psychiatric patients, both boys and girls had increasing rates of depression across this age range, with no gender difference in rates before age 11 (Angold and Rutter, 1992). However, by age 16 girls were twice as likely as boys to have significant depressive symptomatology. When age was controlled for, pubertal status had no effect on depression scores. Depressed girls are at high risk for multiple problems, including early pregnancy. The babies of these girls can be, in turn, at risk for developing a similar affective style.
These two examples—low-birthweight premature births and depression—highlight new directions and frontiers for research in developmental psychopathology. First, there is value in understanding age variations in susceptibility to a wide range of phenomena, including low birthweight, parental psychopathology, brain injury, attachment prob-