Reuters Health
Thursday, September 7, 2006
NEW YORK (Reuters Health) - Sleep problems and depression in
children may share a genetic source, a study of twins hints.
"A range of sleep difficulties are associated
with depression in school-aged children, and the overall association
between the two difficulties maybe largely influenced by genes,"
report Dr. Alice M. Gregory of Kings College London, UK, and
colleagues in the journal Pediatrics.
Sleep problems are thought to be related to anxiety
and depression, but this relationship is complex and poorly
understood. To help clarify the role of genetic and environmental
factors in the anxiety-depression-sleep problem association,
Gregory and her team studied 300 pairs of eight-year-old twins.
Twin studies are useful in teasing out genetic
and environmental influences, the researchers note, because
identical twins share the same genes and the same environment,
while fraternal twins' genetic relatedness is the same as any
other sibling pair, although their environment could be considered
identical.
Parents reported any sleep problems the children
had and the children were assessed for anxiety and depression.
While anxiety showed little relationship to sleep
problems, children with sleep problems had higher levels of
depression, the researchers found. The sleep problems included
resistance at bedtime, delays in getting to sleep, anxiety associated
with sleep, as well as sleep terrors and sleepwalking, related
conditions called parasomnias.
Relationships between sleep and depression were
stronger among identical twin pairs. According to the investigators,
genes played the greatest role in this relationship, while the
influence of environment was smaller.
"The large overlap between genes influencing
depression and those influencing sleep problems suggest that
it may be worth exploring whether genes that are known to influence
depression are associated with sleep problems, and vice versa,"
Gregory and her team conclude. Genes related to the neurotransmitters
serotonin or dopamine may be candidates, they add.
The findings also suggest that doctors should
check for sleep problems in their young patients who show signs
of depression, and vice versa, they add.
SOURCE: Pediatrics, September 2006.
