Touch plays an important role in an infant’s socio-emotional development. Mothers who are depressed are less likely to provide their babies with soothing touch, less able to detect changes in facial expressions, and more likely to have trouble regulating their own emotions.
In addition, infants of depressed mothers exhibit similar brain functioning patterns as their depressed mothers, which also are linked to temperament characteristics. Infants of depressed mothers are at a high risk of atypical and potentially dysregulated social interaction.
A first-of-its-kind study by researchers at Florida Atlantic University’s Charles E. Schmidt College of Science examined the developing mother-infant relationship by studying feeding method (breastfeeding and/or bottle-feeding) and affectionate touch patterns in depressed and non-depressed mother-infant dyads as well examining the infant’s electroencephalogram activity (EEG) during development.
Affectionate touch was coded during the mother-infant feeding context and included stroking, massaging and caressing initiated by either mother or infant.
For the study, researchers evaluated 113 mothers and their infants and assessed maternal depressive symptoms, feeding and temperament or mood. They collected EEG patterns (asymmetry and left and right activity) from infants at 1 and 3 months old and videotaped mother-infant dyads during feeding to assess affectionate touch patterns in both mother and baby.
They specifically focused on alterations in EEG activation patterns in infants across development to determine whether feeding and maternal depression are interactively related to changes in resting frontal EEG asymmetry and power.
Data from EEG activity, published in the journal Neuropsychobiology, revealed that mother-infant affectionate touch differed as a function of mood and feeding method (breastfeeding vs. bottle-feeding), affecting outcomes for infants of depressed mothers compared to non-depressed mothers.
Researchers observed a reduction in infant touch toward their mothers only with the infants in the depressed and bottle-fed group.
Infants of depressed and breastfeeding mothers showed neither behavioral nor brain development dysregulation previously found in infants of depressed mothers.
“We focused on mother-infant affectionate touch patterns during feeding in our study because touch is a form of mutual interaction established in early infancy, used to communicate needs, soothe, and downregulate stress responses, and because mothers and infants spend a significant amount of time feeding across the first three months postpartum,” said Nancy Aaron Jones, Ph.D., lead author, an associate professor, and director of the FAU WAVES Emotion Laboratory in the Department of Psychology in the Charles E. Schmidt College of Science, and a member of the FAU Brain Institute.
“As experience with maternal mood and feeding pervade the infant’s early environment, we chose to examine how these factors interact to affect mother-infant affectionate touch, focusing fastidiously on the key roles of individual variation in temperament and EEG activation patterns.”
Asymmetry patterns in certain infant populations, such as those of depressed mothers differ from the asymmetry patterns of typically developing infants and children. While EEG asymmetry measures the balance of the right and left hemisphere activity, infants of depressed mothers exhibit patterns of right frontal asymmetry, due in part to hypoactivation of the left hemisphere within the frontal region. This pattern of brain activation (greater right asymmetry) is similar to the pattern observed in depressed adults and is thought to represent heightened negative affect as well as motor tendencies for withdrawal and inhibited approach behaviors.
In addition to the tactile behavior changes, the infants in this study displayed differential brain activation patterns as a function of maternal depression and feeding group status. Not only were the infants’ EEG patterns affected by their mother’s depression status, stable breastfeeding experience also interacted with the depression group to impact EEG patterns across early development.
Left frontal asymmetry in infants was associated with having a non-depressed mother and infant care experiences in the form of stable breastfeeding. Left frontal activity has been associated with advancing maturation, positive emotions, as well as higher order processing skills.
Notably, EEG patterns of infants of depressed mothers showed right frontal asymmetry; however, shifts to greater left frontal activation (left frontal hyperactivation change) were found in those infants with stable breastfeeding experiences.
Analysis from the study also revealed that infant breastfeeding duration and positive temperamental characteristics predicted infant affectionate touch patterns, suggesting that early infant experiences, and more broadly, their underlying neurochemical regulatory processes during feeding could influence the development of infant physiology and behavior, even for infants of depressed mothers.
“Ultimately, our study provides evidence that the sensitive caretaking that occurs, even for mothers with postnatal depression in the context of more predominant breastfeeding, may redirect neurophysiological, temperamental, and socio-emotional risk through dyadic tactile experiences across early development,” said Aaron Jones.
Depression is one of the main causes of disability worldwide, and its lifetime prevalence ranges from 20% to 25% in women [1,2]. Women are more vulnerable to depression than men, and the reproductive years are a particularly critical period for its onset .
Depression that occurs during pregnancy is referred to as antenatal or prenatal depression, and depression occurring after childbirth is described as postpartum depression (PPD). The prevalence of prenatal depression increases from 5.4% in early pregnancy to 10.0% in late pregnancy  and prenatal depression is one of the greatest risk factors for developing PPD .
PPD is a common and serious mental health problem, and one that is a source of suffering for both the mother and her offspring. It is often defined as an episode of a major or sometimes minor depressive disorder that occurs anytime within the first year postpartum ; however, most episodes begin within two to three months after giving birth [5,7].
The prevalence of PPD has been estimated to range from 9% to 19% depending on the recognition criteria, the period of time under consideration and population type . The prevalence of PPD is 9.6% among women living in high-income countries [9,10] and 19.6% in low-income and middle-income countries . For comparison, the prevalence of MD among non-pregnant women of childbearing age is 4.8% 
The majority of studies examining depression suggest that it may be associated with problems in the formation of the bond between mother and child [13,14,15,16], particularly in women with a dual/disorganized attachment style . Depressive mothers develop a less-intense relationship with their children, experience more stress, perceive their children in a more negative way and may assess them as less securely attached than non-depressive mothers .
Some experience lowered maternal instinct, as well as greater hostility and aggressive impulses, and a feeling of rejection toward their own children .
Maternal depression also influences the affective state of the infant and impairs their capacity for repairing states of miscoordination. As a result, the infants develop negative affective states that disrupt their social relations. This impact is associated primarily with severe maternal depression but can also manifest in mothers who have only high levels of depressive symptoms .
However, findings from longitudinal studies indicate that the severity and chronicity of maternal depression are associated with higher levels of later childhood behavioural problems [20,21]. Moreover, male infants are more vulnerable than female infants to maternal depression [19,22].
At nine months, the infants of depressed mothers manifest lower social engagement, fewer mature regulatory behaviours and more negative emotionality, and higher cortisol reactivity [23,24]. Some studies have found that the detrimental effect of maternal depression is intensified in mothers with comorbid diagnosis such as anxiety or a personality disorder [25,26,27], and others show that the influence of maternal depression on child development depends on maternal sensitivity and quality of parenting [23,28]. As sensitive parenting requires an accurate and empathic response to signals from the child, the process can be disrupted by changes in the mental state of the parent.
Some studies have indicated that maternal depression has adverse effects on mother–child bonding and child development, and these examine a variety of factors; however, there is an urgent need to determine the influence of maternal depression on the development of the attachment security of the child and to identify the factors that play crucial roles in this process.
Studies in this area tend to focus on individual sets of variables and lack the global analysis needed to gain a comprehensive understanding of the effects of maternal depression. No such systematic review has yet been carried out in this area; existing studies focus either on a broader developmental context  or on the effects of depression treatment .
The aim of this review is to identify and summarize the key findings of empirical studies assessing the influence of maternal depression on the relationship between mother and child, and on child attachment security, measured up to 24 months after birth.
It was decided to use 24 months as a cut-off age for three reasons: (1) to concentrate the analysis on the period of life when children depend mostly on their parents, and thus might be highly affected by any type of parental disturbances or abnormalities; (2) to indicate that intense reorganization takes place in the brain, and the changes are directly related to the attachment style ; and (3) to look at the effects of maternal depression in fairly similar age groups and thus control for a child’s developmental stage.
Thus, the review places particular attention on the period when depression occurs and its most visible effects for attachment security. It also attempts to identify both the protective and adverse factors that might modify the influence of maternal depression.
reference link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216154/
More information: Jillian S. Hardin et al, Affectionate Touch in the Context of Breastfeeding and Maternal Depression Influences Infant Neurodevelopmental and Temperamental Substrates, Neuropsychobiology (2021). DOI: 10.1159/000511604