Children who are still wetting the bed at age seven have lower IQ scores, on average, than their peers who stay dry through the night, UK researchers report.
The findings support the theory that incontinence in children is a genetic phenomenon due to delayed maturation of the central nervous system (CNS), say Dr Carol Joinson of the University of Bristol and colleagues. They call for more research to better understand the intellectual functioning of children who wet the bed, and to determine if bed-wetting is also related to learning and academic problems.
Bed-wetting is a common problem among children, Joinson and her team note, with up to 22% of boys and 15% of girls still wetting the bed by age 7. At this age, 2% to 4% of children will wet themselves during the day, while 2.3% of boys and less than 1% of girls soil themselves.
Link between bed-wetting and IQ?
Children who wet the bed are thought to either have difficulty waking up when their bladders fill, or to have trouble suppressing the reflex to urinate while they are sleeping, Joinson and her team note in the medical journal Pediatrics. To investigate the relationship between bed-wetting and intellectual capacity, as well as soiling and daytime wetting, the researchers looked at more than 6 000 children ranging in age from 7 to 9.
Bed-wetters had lower average IQ scores than children who did not wet the bed, and the relationship remained after the researchers excluded children with IQs below 70, who are considered to be mentally retarded, from their analysis.
The link was strongest for performance IQ, which "represents practical, or 'fluid,' intelligence and reflects innate intellectual abilities that are thought to be largely influenced by neurological and biological factors rather than knowledge that is acquired and influenced by education, family and social context," the investigators note.
While soiling also was linked to lower IQ, most of the relationship could be attributed to study participants with IQs below 70, the researchers found.
Daytime wetting - bladder problems
Children who wet during the day didn't have lower IQs than those who didn't, although they did score worse on certain subsets of the IQ test. Daytime wetting is usually related to bladder problems, so it may have a weaker link with central nervous system function, while soiling is probably more closely related to toilet training problems than neurological development.
Joinson's team concludes that immaturity of the central nervous system underlies both lower IQ scores and bed-wetting. - (Reuters Health)