Optical coherence relationship with serum glial fibrilar acidic protein, β-III tubulin, synaptophysin in patients diagnosed with bipolar disorder

Objective: The etiology of bipolar disorder (BPD) has not been definitively demonstrated, and neurodegenerative and neurodevelopmental processes are thought to play a role in the etiology of bipolar disorder. The aim of this study is to compare serum β-III tubulin, GFAP (glial fibrillary acidic protein), synaptophysin and OCT (optical coherence tomography) measurements, which are neurodegenerative and neurodevelopmental markers, in individuals diagnosed with BPD compared to the healthy control group and to determine the possible relationship between them. Method: The research was designed as cross-sectional and observational. The sample of the study consisted of 43 patients with BPD type I in the euthymic periodand 46 healthy volunteers in a similar age group. Participants' serum β-III tubulin, GFAP, synaptophysin levels were investigated and OCT measurements were performed. Results: In the study, although serum GFAP and synaptophysin levels did not show a statistically significant change in the BPD group compared to the healthy controls, serum β-III tubulin levels were found to be decreased in the BPD group (U=1240,500; p=0,039). Retinal nerve fiber layer (RNFL) thickness was found to be statistically significantly decreased in the inferior and nasal quadrants of the right eye and in the superior, inferior and nasal quadrants of the left eye in the BPD group compared to the healthy control group. ILM-IPT (measurement from the internal limiting membrane to the internal plexiform layer) was found to be statistically significantly decreased in the superotemporal and inferotemporal quadrants of the left eye in the BPD group. No significant relationship was found between serum markers and RNFL and ILM-IPT. Conclusion: The decrease in serum β-III tubulin detected in the current study seems to be related to oxidative stress mechanisms that play a role in the etiology of BPD. The decrease in RNFL thickness and ILM-IPL thickness detected in the BPD group may support evidence for the neurodegeneration hypothesis in the etiology of bipolar disorder. It is recommended that future studies be planned with a larger sample group and neuroimaging. Keywords: bipolar disorder, neurodegeneration, GFAP, synaptophysin, β-III tubulin, RNFL, ILM-IPL