Thyroid Hormone Dysregulation and Lipid Metabolism Alterations in Bipolar Disorder: Associations With Manic Episodes, Aggressive Behaviour and Cognitive Impairment

Abstract

Aims/Background: Patients with bipolar disorder experience lipid metabolism disorders and endocrine dysregulation, which may affect emotional regulation, behavioural habits and cognitive function. This study aimed to investigate the correlations amongst lipid metabolism indicators, thyroid hormone levels, and manic episodes, aggressive behaviours, cognitive function and disease severity in patients with bipolar disorder.

Methods: This retrospective analysis included 656 patients with bipolar disorder admitted to Wuhan Mental Health Center. Baseline data, including manic symptoms (Young Mania Rating Scale), aggressive behaviours (Modified Overt Aggression Scale), cognitive function (Montreal Cognitive Assessment), disease severity (Clinical Global Impressions-Severity), lipid metabolism indicators {total cholesterol (TC), triglycerides (TGs), high-density lipoprotein (HDL), low-density lipoprotein (LDL) and thyroid hormone levels [thyroid-stimulating hormone (TSH), total triiodothyronine (T3), total thyroxine (T4), free triiodothyronine (FT3) and free thyroxine (FT4)]}, were collected through electronic medical records.

Results: No statistically significant differences were observed in serum TC, LDL, TSH, T4 or FT3 levels between the manic episode group and the non-manic group (p > 0.05). However, the manic episode group exhibited significantly higher serum TG, T3 and FT4 levels (p < 0.05) and significantly lower HDL levels (p < 0.05) than the non-manic group. No significant differences were observed in serum TC, TG, HDL or LDL levels between the aggressive behaviour group and the non-aggressive group (p > 0.05). However, the aggressive behaviour group showed significantly higher TSH, T4, T3, FT3 and FT4 levels (p < 0.05) than the non-aggressive group. No significant differences were observed in serum TC, TG, LDL, TSH, T4, T3 or FT3 levels between the cognitive impairment and normal cognition groups (p > 0.05). However, the cognitive impairment group had significantly lower HDL and FT4 levels (p < 0.05) than the normal cognition group. No statistically significant differences were observed in the serum levels of TC, TG, HDL, LDL, TSH, T4, T3, FT3 or FT4 between the moderate and severe bipolar disorder groups (p > 0.05).

Conclusion: Changes in lipid metabolism indicators and thyroid hormone levels in patients with bipolar disorder are closely related to manic episodes, aggressive behaviours and cognitive dysfunction, but no correlation was found with disease severity. This evidence supports precision management of bipolar disorder by utilizing specific lipid and thyroid hormone profiles to guide cardiovascular screening, aggression risk assessment, and early detection of cognitive decline.