Bipolar disorder underlies roughly five percent of all suicides among young people. Previous studies also show that there is often a long delay between the onset of bipolarism and its correct diagnosis and treatment. Researchers at Karolinska Institutet now show that fewer boys commit suicide in Swedish regions where bipolar diagnoses are more common. The study, which is published in JAMA Psychiatry, could contribute to more proactive care for reducing the number of suicides.

"Bipolar disorder is often more distressing for people who develop it early in life and is one of the psychiatric disorders most associated with suicide risk," says the study's first author Peter Andersson, doctoral student at the Department of Clinical Neuroscience, Karolinska Institutet.

The disease usually manifests between the ages of 12 and 25 and is characterized by recurring episodes of mania and depression. Previous studies have shown that it can take up to six years for bipolar disorder to be diagnosed and treated, and comparisons with data from previous large-scale prevalence studies, indicate that under-diagnosis in Sweden is high among individuals aged 15 to 19.

Large regional differences

Using registry data from all of Sweden's 21 regions between 2008 and 2021, researchers from Karolinska Institutet examined regional differences in the number of people aged 15 to 19 diagnosed with bipolar disorder and the correlation between population size-adjusted diagnoses and confirmed suicides for males and females.

The results, which included 585 confirmed suicides in this age group, showed large regional differences in the percentage of young people diagnosed with bipolar disorder.

The study also found an association between a higher number of population-adjusted bipolar diagnoses and lower suicide rates among boys.

"Our results show that the suicide rate among boys is almost five percent lower in the regions that make most bipolar diagnoses than in those that make the fewest," says corresponding author Adrian E. Desai Boström, resident in child and adolescent psychiatry in Stockholm and postdoc researcher at the Department of Clinical Neuroscience, Karolinska Institutet. "This suggests that suicide among teenage boys in Sweden could be reduced with improvements to the diagnosis of bipolarism and its treatment."

Sometimes wrongly diagnosed

The study's complementary analyses showed that the relationship between the number of bipolar diagnoses and lower suicide rates among boys was independent of the number of care episodes and diagnoses of depression or schizophrenia.

Although the number of prescriptions for the mood stabilizer lithium paradoxically decreased when more bipolar diagnoses were established, increases were observed in the number of boys who received lithium at least once. The researchers hypothesized that this could be interpreted as indicating that boys with bipolar disorder often begin lithium therapy but then switch to other mood-stabilizing drugs for various reasons.

The researchers also see a possible risk that misguided treatment could lead to a higher suicide rate rather than no treatment at all.

"For example, some young people might be passed on by the psychiatric services to the social services under the provisions of laws relating to the care of the young and people with functional impairments," says Andersson. "We also know that bipolar patients are sometimes wrongly diagnosed with 'normal' depression."

In a recently published study in Nature Communications the researchers found large regional differences in the use of advanced psychiatric treatments in child and adolescent psychiatry in Sweden. They now plan to further investigate the effects of advanced psychiatric treatments on young people with bipolar disorder and other serious psychiatric conditions.

The study was a collaboration among researchers at Karolinska Institutet, Uppsala University, Umeå University, Lund University, Region Halland, and Region Stockholm in Sweden and was financed by the Swedish Research Council.