Nerve development link to bedwetting

Children in the study undertook a drawing test

Bedwetting could be due to a delay in how the nervous system develops, scientists say.

Around 10% of children are still wetting the bed by the age of eight, and the condition can cause them and their parents a great deal of distress.

Researchers from Leeds General Infirmary suggest the cause in some children could be problems in neurological development before and after birth.

Knowing why children wet the bed will help doctors tailor treatment to an individual child.

It's useful to show that it's not anybody's fault, it's just the way the child is put together.

Dr Jonathan Evans, City Hospital, Nottingham

The findings could also help doctors advise parents on how the likelihood of bedwetting could be reduced - breastfeeding is one factor which appears to reduce the chance a child will be affected, researchers say.

The researchers add that those affected by the developmental problem will catch up.

Daily rhythms

The team studied 34 children, aged between seven and 13, who wet the bed at least four times a week.

All were being treated at a specialist clinic and were given a synthetic version of the hormone vasopressin.

This hormone is produced by the pituitary gland. The body should produce more of it at night so that less urine is produced during sleep.

But in some that fails to happen.

This could be because the natural daily rhythms of the body fail to work and the body fails to recognise it needs to restrict urine production because it is night.

Hormone treatment can help this.

But in children who have neurological development problems, the researchers suggest bedwetting could be due to problems in the growth of nerves in the mid brain and hypothalamus.

Drawing

The Leeds team discovered that whether or not a child has these problems can be predicted by a drawing test.

The neuro-psychological test has been used for over 60 years. It asks children to accurately copy a complex line drawing, then draw it again from memory.

The children were scored on how many times they made mistakes in the lines and shapes in the figure.

Eleven children who did not respond to the synthetic version of vasopressin made at least three mistakes, more than those who did respond.

This suggests they have a neuro-developmental - rather than a circadian rhythm - problem.

Dr Philip Holland, consultant paediatrician at Leeds who led the research, told BBC News Online: "When people see 'developmental delay', they associate that with intelligence delay, and think the child won't get better and it's not treatable. Both are incorrect."

Since the team started using the test, they have increased their success rate for treating children from 25% to 80%.

Dr Jonathan Evans, a paediatric kidney specialist at City Hospital in Nottingham, told BBC News Online: "This is another piece of the jigsaw that says to us there is an organic cause.

"It's useful in the short-term to show that it's not anybody's fault, it's just the way the child is put together.

"In the long-term, it will start to help us understand night-time bedwetting."

The research was published in the journal Archives of Disease in Childhood.