Gender Differences in Clinical and Biochemical Variables of Patients Affected by Bipolar Disorder

Introduction: Bipolar disorder (BD) affects over 1% of the global population and significantly impacts psychosocial functioning and life expectancy. This manuscript has the objective of investigating gender differences in the clinical and biochemical parameters of patients affected by BD. Methods: This retrospective cross-sectional study examined 672 patients diagnosed with BD in psychiatric wards in Milan and Monza. Clinical data and biochemical parameters were collected on the first day of hospitalization. Independent sample t-tests, chi-square tests and binary logistic regressions were performed to identify gender differences in BD. Results: With regard to univariate analyses, women were found to be more susceptible to psychiatric comorbidities (χ2 = 12.75, p < 0.01), medical comorbidities (χ2 = 45.38, p < 0.01), obesity (χ2 = 6.75, p = 0.01) and hypercholesterolemia (χ2 = 23.54, p < 0.01), as well as to having more mood episodes in the year prior to hospitalization (t = 5.69, p < 0.01). Men were found to be more likely to develop psychotic symptoms (χ2 = 4.40, p = 0.04), to be tobacco smokers (χ2 = 15.13, p < 0.01) and to have substance abuse disorders (χ2 = 14.66, p = <0.01). Logistic regression analyses showed that women compared to men showed more psychiatric comorbidity (p < 0.01), higher Global Assessment of Functioning (GAF) scores (p = 0.05) and higher total cholesterol plasma levels (p < 0.01); however, they also had fewer red blood cells (p < 0.01) and lower creatinine plasma levels (p < 0.01). Conclusions: Female patients (compared to males) exhibited higher levels of global functioning despite the higher frequency of psychiatric comorbidity and susceptibility to metabolic complications; consistent with earlier studies, female patients also showed higher cholesterol levels. Further studies will have to confirm the present findings and identify gender-related clinical pathways for the management of BD.