ACE's are Adverse Childhood Experiences. They are negative life experiences that may have an effect on a child's health and/or development.  It is argued that a child has serious effects on health when there are four or more ACE's. They are usually measured by using a checklist in an interview, or by giving a survey. 

This is problematic for a few reasons.  First, there is the problem that is self-reported and retrospective.  The memories cannot always be verified for authenticity and there may be some memory distortion.  More likely, there could be repression of childhood events or, depending on the age at which something happened, it could be that there is no clear memory.

Another problem is that depending on the age of the child, there may be difficulties in explaining the situation due to language.  Or it could be out of a fear that a family member will get in trouble, in the case of abuse.

There are several potential answers to this question, including but not limited to:  increased levels of cortisol which may result in hippocampal cell death or impairment; smaller brains - including smaller hippocampi and smaller frontal lobe development; psychosocial dwarfism as a result of lower levels of growth hormone; lower levels of oxytocin; lower levels of neurogenesis.  All of these support Piaget's claim that biological development precedes cognitive development. 

The study was both longitudinal and had a large sample size.  The orphans' cognitive and social development was measured as they were adopted - meaning that the study is also prospective in nature.  There was no clear selection bias in the study as the children were not given up for health reasons, but due to the general poverty in Romania. There are other studies that confirm the findings of the original study. The children were also ethnically similar to the parents, meaning that there was not a confounding variable of feeling different from the parents.

A response-dose relationship is a term used in abnormal psychology which indicates a positive correlation.  So, in the Rutter study, the longer the children had been institutionalized, the higher their levels of cognitive impairment and attachment disorders.

Koluchuv's study showed that the twins were able to catch up to the physical and cognitive level of their peers in a period of only two years. However, social development was delayed. It appears that physical development then precedes cognitive development - and this may then be necessary for social development.  However, the study did not find that the children were able to develop trusting behaviours of their peers because the study was discontinued.

Oxytocin inhibits the activity of the amygdala.  This may result in an individual being more trusting of others by lowering the fear response.  In addition, since the amygdala plays an important role in the creation of emotional memories associated with PTSD and trauma responses, oxytocin may play a role in the prevention of the creation of such powerful memories.

One limitation is that takes a reductionist approach to resilience. Simply noting amygdalar response in the brain does not necessarily predict resilience.

In addition, there is a question about the role that the fMRI itself may have played in amygdalar response from some of the participants.  Fear of the machine itself - the noise and the claustrophobic nature of the tunnel - may lead to artifacts in the scanning.

In addition, it may well be that those people who are in a long-term and loving relationship may be resilient themselves - that is, it may be because they are resilient that they are still happy in a long-term married relationship.  After all, relationships are not easy.  So, it may not be the presence of their significant other that makes a difference as much as their own level of resilience.  It is not possible to isolate these variables in the experiment.

Finally, the situation is highly artificial and may not be applied to real-life situations in which resilience could be demonstrated.

Neuropeptide y is part of the "brake" that stops the stress response of the HPA axis.

One of the problems of research on trauma is the ability to measure trauma.  For example, although all of us assume that war is traumatic for children, all children will experience it differently.  The same with divorce, domestic violence, poverty, and abuse. When looking at the role of ACE's on a child's health, not all adverse childhood experiences are equal.  Trauma is not just the environmental trigger, but the way in which one processes and makes meaning out of that experience.

In addition, much of the research on trauma and deprivation uses a case study method. As the situations are often very different, psychologists need to look for similarities in order to determine the level to which a case study could be generalized to explain another case.