The presence of nerve growth factor (NGF) might be a useful biomarker for the early detection of conversion to bipolar disorder (BD) in women with major depressive disorder (MDD), thus assisting clinicians in rendering a clinical diagnosis. A prospective longitudinal study on the topic was conducted at the Universidade Católica de Pelotas (UCPel), located in Pelotas, Brazil, and the results were published in Psychiatry and Clinical Neurosciences.

The investigators sought to identify biomarkers associated with MDD and conversion from MDD to BD in an outpatient sample of women treated at the Research and Extension in Mental Health Clinic (APESM) of UCPel. The study was performed in 2 phases. In the first phase, which was carried out between 2012 and 2015 at the APESM of UCPel, comprised women aged 18 to 60 years who had been diagnosed with MDD. The diagnosis was made by well-trained psychologists using the Mini International Interview Plus. The second phase of the study was conducted between 2017 and 2018 — an average of 3 years after the first phase. All of the women who were diagnosed with MDD evaluated in the first phase were invited to participate in the second phase.

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A total of 156 women were enrolled in the study, of whom 142 were experiencing a current episode of MDD and 14 had experienced a past episode of the disorder. Overall, the conversion rate from MDD to BD was reported in 24 of the patients (15.4%). NGF serum levels were significantly elevated in women who converted from MDD to BD compared with women with remitted MDD or current MDD (P =.013). Moreover, per Bonferroni post hoc test for multiple comparisons, significant differences in higher NGF levels were observed in women who converted to BD compared with women with current MDD (P =.037). No differences in serum levels of interleukin-6, tumor necrosis factor-alpha, brain-derived neurotrophic factor, or glial-cell-derived neurotrophic factor were reported between the groups.

The investigators concluded that knowledge of the physiologic changes linked to conversion from MDD to BD can help improve our understanding of the genesis and the mechanisms involved in these disorders. Additional studies are warranted in order to further elucidate the role played by NGF and other biomarkers in the conversion from MDD to BD, particularly in women.


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Reference
Pedrotti Moreira F, Cardoso TC, Mondin TC, et al. Serum level of nerve growth factor is a potential biomarker of conversion to bipolar disorder in women with major depressive disorder [published online June 6, 2019]. Psychiatry Clin Neurosci. doi:10.1111/pcn.12896