Bipolar Disorder Linked To Higher Rates of Medical Illness
Individuals who experience bipolar disorder have higher rates of medical illness than those with unipolar depression and the general population, according to the findings of a UK study published in The British Journal of Psychiatry.
“This comorbidity needs to be taken into account by services in order to improve outcomes for patients with bipolar disorder and also in research investigating the aetiology of affective disorder where shared biological pathways may play a role”, say study authors Nick Craddock (Cardiff University) et al.
The team of researchers surveyed 1720 patients with a median age of 47 years old who had been diagnosed with bipolar disorder. The interviews with the patients, who were largely women, asked about their lifetime history with 20 common medical illnesses, and then compared the rates of illness in participants with those who were observed with recurrent unipolar depression as well as control groups.
As supported by previous studies, the most prevalent medical conditions in both the bipolar and unipolar groups were migraine headache, asthma, elevated lipids, hypertension, thyroid disease, and osteoarthritis. However, there were notable differences in comorbid illness prevalence among the included groups, except for the rates of Type 1 diabetes.
After adjustment for multiple testing, these differences remained significant for asthma, Type 2 diabetes, elevated lipids, epilepsy, gastric ulcers, hypertension, kidney disease, multiple sclerosis, osteoarthritis and thyroid disease, with the highest rates generally observed among the patients with bipolar disorder.
In order to assess whether more serious bipolar illness is associated with a greater rate of medical illness and medical burden, the team then compared patients with a history of three or more medical illnesses with those with no medical illness history.
The team saw that high medical illness burden was significantly associated with a history of anxiety disorder, rapid cycling mood episodes, suicide attempts, and mood episodes with a typically acute onset.
However, the findings contradict some previous studies by finding no significant differences between the bipolar group with no history of medical illness and those with a high burden of medical illness in the rates of substance abuse.
“Although this finding requires further investigation it suggests that, at least in our bipolar sample, smoking and alcohol misuse may not be the most significant factors influencing susceptibility to medical illness burden”, Craddock et al remark.
The authors conclude that “[k]nowing which medical illnesses are likely to coexist with a mood disorder may help to improve diagnostics and management and therefore clinical and social care for patients.”