Prevalence of affective disorders and dementia in inflammatory polyarthropathies

Comorbid disorders are common in psychiatric diseases and understanding the risk of secondary diseases can aid successful clinical treatment. The objective of this study was to compare the frequency of comorbid dementia, affective disorders, and inflammatory polyarthropathies. Healthcare data obtained via the German Hospital Fees Act from two independent databases with more than 7.4 million cases were analyzed to compare the prevalence of comorbid disorders. Comorbid inflammatory polyarthropathy was observed in 2.27% of patients diagnosed with affective disorders and 1.35% of patients with dementia (p < 0.001). Among patients with a primary diagnosis of inflammatory polyarthropathy, 1.27% of patients were diagnosed with dementia, whereas 4.55% of age-matched patients without inflammatory polyarthropathies had comorbid dementia (p < 0.001). The opposite effect was demonstrated for affective disorders, as 5.77% of patients with a primary diagnosis of inflammatory polyarthropathy also had comorbid affective disorders, while 4.87% of age-matched patients without inflammatory polyarthropathy had an accompanying affective disease (p < 0.001). These findings show an association between the occurrence of inflammatory polyarthropathies, dementia, and affective disorders. This correlation might improve diagnosis and treatment for patients with comorbidities. Moreover, further exploration of the molecular pathophysiology underlying these relationships could be relevant for the development of novel treatment options.