Exploring the association between bipolar disorder and uric acid: A mediation analysis.
OBJECTIVE
Recent evidence shows that bipolar disorder might be associated with a purinergic system dysfunction. This study aimed at (i) testing the association between bipolar disorder and uric acid serum levels, and (ii) clarifying whether this relationship is mediated by metabolic syndrome and other relevant metabolic parameters.


METHODS
Patients consecutively admitted to a Mental Health Inpatient Unit, with a diagnosis of bipolar disorder or other severe mental disorders, and an appropriate healthy control sample, were included in this cross-sectional, exploratory study. We performed linear regression analyses, to explore factors associated with uric acid levels, and formal tests of mediation to assess mediating effect of candidate variables.


RESULTS
176 individuals with mental disorders and 89 healthy controls met inclusion criteria. Bipolar disorder was the only diagnostic subgroup significantly associated with increased uric acid levels. Furthermore, male gender, metabolic syndrome, as well as abdominal circumference and triglycerides levels, had a significant effect on uric acid. Relevant mediation analyses showed that the estimated effect between bipolar disorder and uric acid levels was only partially mediated by metabolic abnormalities.


CONCLUSIONS
This study suggests a direct association between bipolar disorder and uric acid levels, only partially mediated by metabolic abnormalities. It seems consistent with results of previous studies highlighting a purinergic dysfunction in bipolar disorder and the role that purinergic modulators, lowering uric acid levels, could have in clinical practice.
Department of Medicine and Surgery, University of Milano Bicocca, Milano, Italy. Electronic address: f.bartoli@campus.unimib.it.
Francesco
F
Bartoli
Department of Medicine and Surgery, University of Milano Bicocca, Milano, Italy.
Cristina
C
Crocamo
Department of Medicine and Surgery, University of Milano Bicocca, Milano, Italy.
Giulia Maria
GM
Gennaro
Department of Medicine and Surgery, University of Milano Bicocca, Milano, Italy.
Gloria
G
Castagna
Department of Medicine and Surgery, University of Milano Bicocca, Milano, Italy.
Giulia
G
Trotta
Department of Medicine and Surgery, University of Milano Bicocca, Milano, Italy.
Massimo
M
Clerici
Department of Medicine and Surgery, University of Milano Bicocca, Milano, Italy; Division of Psychiatry, University College London, London, UK.
Giuseppe
G
Carrà
D000328:Adult; D001714:Bipolar Disorder / Q000097:blood* / Q000150:complications; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000150:complications; D008875:Middle Aged; D014527:Uric Acid / Q000097:blood*; D055815:Young Adult
D014527:Uric Acid
Bipolar disorder; Mediation analysis; Metabolic syndrome; Purinergic system; Uric acid