Photo Credit: Melitas

The following is a summary of “Association between olfactory function and metabolic syndrome in bipolar disorder patients: a cross-sectional study,” published in the October 2024 issue of Psychiatry by Yuan et al. 

Olfactory function is linked to mood and the endocrine system, yet its role in patients with bipolar disorder and metabolic syndrome remains unclear. Clarifying this relationship could enhance understanding of their health challenges. 

Researchers conducted a prospective study to explore the associations among olfactory function, tumor necrosis factor alpha (TNF-α), and metabolic syndrome in patients with bipolar disorder. 

They divided 96 patients with bipolar disorder into 2 groups with and without metabolic syndrome and included 46 healthy controls. Olfactory function was assessed using the Sniffin’ Sticks test, and blood samples were collected to measure metabolic indicators and serum TNF-α levels. 

The results showed significant differences in olfactory function among the 3 groups. The bipolar disorder without metabolic syndrome group had poorer olfactory identification (P < 0.001) compared to healthy controls, while the bipolar disorder with metabolic syndrome group exhibited impaired olfactory sensitivity (P = 0.003) and identification (P < 0.001). Additionally, the bipolar disorder with metabolic syndrome group had poorer olfactory identification than the bipolar disorder without metabolic syndrome group (P = 0.015). Both bipolar disorder groups had lower TNF-α levels than healthy controls, with no significant difference between patient groups. In the bipolar disorder with metabolic syndrome group, olfactory identification was negatively correlated with systolic blood pressure (r = − 0.424, P = 0.031), and TNF-α levels were negatively correlated with body mass index (BMI; r = − 0.398, P = 0.049), triglycerides (r = − 0.503, P = 0.010), total cholesterol (r = − 0.491, P = 0.013), and low-density lipoprotein-cholesterol (r = − 0.491, P = 0.013). 

Investigators concluded that patients with bipolar disorder have poorer olfactory identification than healthy controls, with metabolic syndrome exacerbating this impairment and enhancing the link between serum TNF-α levels and metabolic indicators. 

Source: bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-024-06164-6#Abs1