In the study, published in Development and Psychopathology, children reported to have chronic health problems showed higher rates of mental illness at 10 years, and those health problems continued to be associated with poor mental health at the ages of 13 and 15.
To carry out the study, researchers reviewed a sample of approximately 7000 children to investigate the occurrence of mental health disorders, including anxiety or depression, and chronic illness. The measure of chronic illness was based on mothers assessing their child's health at 10 and 13.
Since chronic conditions are defined as those that cannot be cured but can be controlled by medication and other therapies, and may have little disease activity, this measure included children presenting with minor health problems.
The researchers found that children with chronic health conditions were approximately twice as likely at 10 and at 13 to present with a mental health disorder than the control group (children reported by their mothers to be 'healthy, no problems'). At age 15, children with chronic health problems were 60% more likely to present with such disorders.
Although the link between chronic health conditions and mental health problems in childhood has been made before, this study provides the strongest evidence of it to date in the years of late childhood and early adolescence.
The difference chronic conditions make to mental health are concerning, and the first impact can be seen even before adolescence, in late childhood."
Dr Ann Marie Brady,Study Author, Queen Mary University of London
To investigate this pattern further, the researchers looked at a subset of the children with chronic illness: those who had been diagnosed with asthma.
Asthma symptoms are generally mild and well-controlled. Nevertheless, researchers found that asthmatic children showed a similar pattern, having a higher rate of mental illness at 10, 13 and 15 than healthy children.
The study also reviewed what additional factors might account for the link between chronic conditions and mental illness.
The sample was taken from the Children of the 90s study, which also contains information from parents and children about other issues including family functioning, friendships, children's activity levels, bullying and health-related absenteeism from school.
Researchers analyzed which of these might contribute to mental illness rates among children with chronic illness.
They found that bullying and health-related school absenteeism emerged as the most significant additional factors for children with mental health issues. Health-related school absenteeism was identified as the most consistent factor predicting mental health problems over time.
Dr Brady said: "Chronic illness disrupts children's normal lives, and this can affect their development and wellbeing. Even children with asthma, a generally treatable and less debilitating chronic condition, had higher rates of mental illness than the healthy children in our study. If children with chronic conditions are more likely to miss school, or experience bullying, that can make the situation worse. Keeping an eye on school attendance and looking out for evidence of bullying amongst children with chronic illness may help to identify those who are most at risk."
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