Washington D.C. [USA], Aug 21 : Low levels of vitamin D in middle childhood could lead to aggressive behaviour as well as anxious and depressive moods during adolescence, suggests a new study of school children.
The University of Michigan study was published in the 'Journal of Nutrition'.
"Children who have vitamin D deficiency during their elementary school years appear to have higher scores on tests that measure behaviour problems when they reach adolescence," said Eduardo Villamor, professor of epidemiology at the U-M School of Public Health and senior author of the study.
Children with blood vitamin D levels suggestive of deficiency were almost twice as likely to develop externalizing behaviour problems, aggressive and rule breaking behaviours, as reported by their parents, compared with children who had higher levels of the vitamin.
Also, low levels of the protein that transports vitamin D in the blood were related to more self-reported aggressive behaviour and anxious/depressed symptoms. The associations were independent of a child, parental and household characteristics.
Villamor said vitamin D deficiency has been associated with other mental health problems in adulthood, including depression and schizophrenia, and some studies have focused on the effect of vitamin D status during pregnancy and childhood. However, few studies have extended into adolescence, the stage when behaviour problems may first appear and become serious conditions.
In 2006, Villamor's team recruited 3,202 children aged 5-12 years into a cohort study in through a random selection from primary public schools. The investigators obtained information on the children's daily habits, maternal education level, weight, and height, as well as the household's food insecurity and socioeconomic status. Researchers also took blood samples.
After about six years, when the children were 11-18 years old, the investigators conducted in-person follow-up interviews in a random group of one-third of the participants, assessing the children's behaviour through questionnaires that were administered to the children themselves and their parents. The vitamin D analyses included 273 of those participants.
While the authors acknowledge the study's limitations, including a lack of baseline behaviour measures, their results indicate the need for additional studies involving neurobehavioural outcomes in other populations where vitamin D deficiency may be a public health problem.