Mothers' neglect changes infants' brain development

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Mothers' neglect changes infants' brain development

http://www.newscientist.com/news/news.jsp?id=ns99991569

 

10:38 15 November 01

 

 

Early maternal neglect changes the expression of genes involved in the

development of the dopamine system, research on mice has revealed.

 

Abnormal regulation of dopamine in the brain has been linked to drug abuse,

depression and personality disorders - conditions that are also associated

with childhood neglect in humans.

 

" Clearly, if the dopamine system of the brain is compromised, and if this

can be extrapolated to humans, it could lead to greater susceptibility for

drug dependence and perhaps greater vulnerability to develop certain

psychiatric illnesses, " says researcher Wayne Brake of the University of

California, Santa Barbara.

 

" Perhaps some people are taking drugs not because they are unhappy with

their childhood, but because there is a window of development that sets gene

expression which is influenced by maternal deprivation, " he adds. These

results " might wake up some politicians to say we can prevent some of these

problems in society " .

 

 

Lack of stimulation

 

 

Previous animal work has shown that it is a lack of stimulation and

interaction that causes behavioural problems in neglected offspring, rather

than early stress, for example.

 

Bruce McKewen, an expert on maternal separation at Rockefeller University,

says it is reasonable to suspect that the effects of deprivation on gene

expression in humans will be similar to the observed effects in mice.

 

He adds: " We now need to look at the brains of children with non-invasive

imaging to show that their developmental trajectory is changed by some of

these [deprivation] variables. This hasn't been done yet. "

 

 

Memory and motivation

 

 

Brake's team separated newborn mice from their mothers for three hours a day

for the normal duration of mouse maternal care - seven days. Next, they

scanned 30,000 genes to look for changes in expression in two brain areas:

the hippocampus, which is involved in memory and is often smaller in

depressed people, and the prefrontal cortex, which is involved in motivation

and anxiety.

 

They found that the expression of several genes that are involved in the

creation of new connections between neurons changed. " This suggests that the

brain is developing differently in these mice and that perhaps nerve cells

are making their connections in a different manner, " Brake says.

 

The team also found changes in the expression of genes involved in the

development of the dopamine system. An overactive dopamine system is

associated with schizophrenia, and reduced dopamine levels are found in

patients with major depression.

 

 

Nature vs nurture

 

 

Understanding the role of early maternal separation on gene expression is

essential if attempts to reverse the effects of neglect are to be properly

formulated, say researchers.

 

But the key aim would be to prevent the brain changes by setting up

programmes to properly support new mothers, says Brake.

 

Ultimately, his team plans to insert genes known to be risk factors for

certain psychiatric diseases into mice, to study how early maternal

separation combined with these genes alters brain development. This will

help them tease apart the genetic and environmental causes of psychiatric

illness.

 

Brake presented his research at the annual meeting of the Society for

Neuroscience in San Diego.

 

 

Emma Young, San Diego

 

 

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