The research hypothesis (question)
The research hypothesis of the article is to compare the serum concentration of neurotrophic factors in depression patients and healthy control. Besides, the article analyzes correlations between serum neurotrophin levels and clinical severity.
The main study variable(s)
The primary variables are serum level, brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and neurotrophin-3 (NT-3). The independent variable is serum level, while brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and neurotrophin-3 (NT-3) are dependent variables. Considering the independent variable (serum) is determined by the amounts applied; then, the level of measurement of the variables is the interval. Besides, the variables are discrete.
Statistical test used
The statistical tests used include non-parametric (Wilcoxon Rank sum test) statistics, one-way ANOVA, chi-square test, regression analysis (multiple linear regression), and correction (Bonferroni correlation and Spearman’s correlation coefficient (ρ).
Conclusions made based on the results of the statistical test
The study showed a decline in serum levels of BDNF, GDNF, and NGF neurotrophic factors in depression patients. Again, the statistical tests showed a gender difference regarding neurotrophin levels. In particular, there were significantly lower serum levels of NT-3 and NGF in female patients than their male counterparts, as well as in female control (healthy) groups. Further, the statistical tests on the adolescent age group showed a clear correlation between clinical psychometric scores of BDI-II and all neurotrophin levels (BDNF, GDNF, NT-3, and NGF. Specifically, a lower level of neurotrophins is a sign of a higher clinical, psychometric score of depression. Finally, the statistical tests did not establish any significant correlation between neurotrophin levels and anxiety score per se.
Reference
Pallavi, P., Sagar, R., Mehta, M., Sharma, S., Subramanium, A., Shamshi, F.,…Mukhopadhyay, A. K. (2013). Serum neurotrophic factors in adolescent depression: Gender difference and correlation with clinical severity. Journal of Affective Disorders, 150(2), 415–423.