The brain structure and function of children who are placed in child care may change due to higher levels of 
stress, a new study has claimed.
In an article published in The Biologist, a journal of the Society of Biology, Dr Aric Sigman proposes that the biological impact of day care now needs to be considered in child care decisions, especially when some research has shown that child care can trigger stress in young children.
Dr Sigman, who gave a talk to the Iona Institute in February, points to studies showing that 70 to 80 per cent of children in centre-based day care show ever-increasing levels of the stress hormone cortisol throughout the day.
According to the research, the biggest increases occur in toddlers.
Increased levels of stress hormones are worrying because their routine elevation could lead to changes in a child’s neuroendocrine networks, which could have potential long-term implications for their adult health.
Half of British mothers go out to work before their child is 12 months old.
Increased levels of cortisol are a response to fear or uncertainty, and is produced by a network of glands and organs known as the hypothalamic-pituitary-adrenal axis (HPAA).
This network is programmed by early childcare experiences. A deficiency in maternal care can produce changes in gene expression in brain regions vital in the HPAA stress response.
Prolonged cortisol exposure can be toxic to both specific nerve cells and entire neural systems.
Increased cortisol exposure has been linked to a higher number of atherosclerotic plaques, and high levels are associated with cardiovascular death.
Children who receive less nurturing early in life may be less securely attached as adolescents and adults, and be more vulnerable to stress.
This can influence the response of blood pressure in adolescents to everyday social interactions; this response may also be due to cortisol.
According to research, the degree of attentiveness by the mother in early childhood is thought to alter the size of the hippocampus, a part of the brain linked to short and long term memory.
Clusters of grey matter in the hippocampus have been linked with human attachment styles including parameters such as attachment anxiety and attachment avoidance.
According to the study, the availability of a parent or adult caring for young children to respond appropriately to normal day-to-day events which may trigger stress reactions is crucial.
Without learning the appropriate stress response to these situations, the cortisol cycle can be disrupted.
Dr Sigman proposes that the three key factors for the effect of childcare on cortisol levels are the quality of the care, the time spent in day care and the age of onset of the care.
When deciding on childcare options, parents have to consider affordability, flexibility of childcare arrangements, and the quality of the services offered, amongst other factors.