Associations between prenatal stress, anxiety and depression and child behavioural and cognitive development. Is it causal?

I (V.G.) first got to know Channi at the inaugural Indian Biological Psychiatry meeting In Bombay over 20 years ago. I was working on monoamine oxidase at the time. It was my first trip to India and his first to Bombay for several decades. We spent much time talking together, and by the end of it, as well as visiting temples, the Gateway of India, and the Elephanta Caves. Channi had persuaded me to carry out research on maternal mood in the perinatal period, the effects on the child, and the underlying biological mechanisms. This I have been doing ever since. Thus for me, like many others, Channi changed the direction of my career. His infectious enthusiasm, and very wide range of interests, have directed and inspired world research in perinatal psychiatry. There is now considerable evidence from both human and animal studies that the children of stressed, anxious, or depressed mothers are more likely to experience a range of neurodevelopmental problems than the children of unstressed mothers. (Glover 2011; O’Donnell et al. 2009; Talge et al. 2007; Van den Bergh et al. 2007,). With animal studies it is much easier to establish that these associations are causal. Newborn rat pups of prenatally stressed mothers can be cross-fostered to non-stressed mothers on the first day after birth, with control pups of unstressed mothers cross-fostered also. This can establish that any differences in outcome are caused by stress in the prenatal period. Many such studies have shown that there are definite fetal programming effects of prenatal stress on behaviour, cognitive development, the hypothalamuspituitaryadrenal (HPA) axis, and brain structure and function of the offspring (e.g. Henry et al. 1994; Weinstock 2001, 2008; Afadlal et al. 2010). The nature of the effects can be affected by the timing of the exposure in gestation, the type of the stress, the strain of the animal, the age at which the offspring was tested, and the sex of the offspring (Weinstock 2008), The effects of prenatal stress on the offspring can often be mimicked by giving the stress hormone corticosterone, or a synthetic glucocorticoid, to the pregnant animal (Matthews 2000; Afadlal et al. 2009).