Family matters in type 1 and mental health
Reporting at the EASD’s 57th Annual Meeting, a team at the Karolinska Institute has found that mental health issues like depression and anxiety affect not just the person with type 1 diabetes, but their family as well. It seems that both genetics and shared environment likely contribute to this association.
It has long been known that children and adults with type 1 diabetes run an increased risk of mental health disorders, including depression, anxiety and stress-related problems. These have been shown to be associated with less than optimal diabetes management, reduced quality of life, higher risk of complications and even premature mortality. The underlying mechanism of the link between depression, and so on, and type 1 is poorly understood but it seems there is more to it than just the 24/7 burden of managing the condition. “Previous research shows us that type 1 diabetes and mental health problems actually tend to aggregate within families, suggesting that genetics and shared environmental factors can contribute,” says Shengxin Liu, a PhD student at the Karolinska Institute in Solna, Sweden.
She and her colleagues have been working on a new population-based study to investigate the link between childhood onset type 1 diabetes and the later onset of depression, anxiety or a stress-related disorder. They also looked at the family patterns involved in this link.
Sweden is famous for its huge medical databases – a rich source of information that has fuelled so many key research studies in diabetes. The source for this new study was the Swedish Total Population Register, focusing on those born in Sweden from 1973 to 2007. A multigenerational population register revealed sub-cohorts of parents, siblings, half-siblings and cousins for each individual in the above time period – a detailed family tree, in other words. The researchers then looked into the Swedish Diabetes Register for cases of type 1 diabetes and identified mental health diagnoses and related prescriptions from the National Patient Register and the Prescribed Drug Register.
“Our statistical analysis compared people with type 1 diabetes with those without type 1 diabetes. And then we compared relatives of those with type 1 diabetes with those without type 1 diabetes, using what we had from these databases,”said Shengxin. The researchers assumed that different relatives shared different levels of their genetics and environment. So, for example, a full sibling shares 50% of genetics with the index person and would usually share their environment, at least in their earlier years.
The study included 20,000 individuals with type 1 diabetes, with a mean age of onset of 9.6 years and a huge group of 3 million people without diabetes as a comparison. It was clear that mental health disorders were more common among those with type 1 diabetes. Overall, 10.8% of those with type 1 diabetes were recorded as having a mental disorder, compared with 6.9% in the comparison group. Rates for depression were 6.9% compared with 3.9%, for anxiety 5.4% versus 2.9% and for stress-related disorders 3.2% versus 2.0%.
Prescription of medications for these conditions was also used as a marker of increased mental health problems among the type 1 diabetes population. So prescription of antidepressant and anxiolytic medication was 19.5% in the type 1 diabetes group, compared with 16.1% in the comparison group.
“These differences start being visible in those with type 1 diabetes about two years after diagnosis,” Shengxin said. “And, after 30 years of follow-up, 26.6% of those with type 1 diabetes had received a mental disorder diagnosis and 49.2% had used medication for this, compared with 18.1% and 31% in our matched comparison group.”
This all means that individuals with type 1 diabetes have a 1.45 to 1.75 higher chance of being diagnosed with depression, anxiety or a stress-related disorder and were also more likely to be using medication for this.
The family connection
When it came to the family, the parents and siblings of those with a type 1 diagnosis did show an increased risk of a mental disorder like depression, compared with those who didn’t have the condition in the family. But half siblings and cousins of the index were no more likely to have a mental disorder than those in the comparison group. “The risk of depression and related disorders increased with relatedness,” said Shengxin. “This indicates a contribution from shared genetics, as siblings were more at risk than half siblings. Our study confirms that children and adults with type 1 diabetes are at higher risk of depression, anxiety and stress-related disorders as are their close family. This elevated risk starts being visible almost straight after diagnosis.”
She believes that the familial co-aggregation pattern that was observed in the relatives suggests that shared familial factors, especially genetic factors, may underlie the aetiology of type 1 diabetes and associated mental disorders.
So, does this mean that there are genes, yet to be discovered, that somehow influence both type 1 diabetes and depression? “Of course, further studies are needed for better understanding, such as larger familial studies and quantitative genetics to quantify the contribution of genetics and environment and molecular genetic studies to identify the susceptibility genes underlying high co-occurrence of type 1 diabetes and psychiatric disorders,” Shengxin concluded.
Whatever the outcome of this further research, it’s a reminder that type 1 diabetes doesn’t just affect the individual who’s been diagnosed – its impact reaches the close family in terms of mental health. So family members should always be included when it comes to the diabetes team offering emotional support in type 1 diabetes.
Any opinions expressed in this article are those of the author, Dr Eleanor D Kennedy.
For more on providing psychosocial support for people with type 1 diabetes, see the latest ADA/EASD consensus report.