In fact, studies have shown that chronic stress can cause complications such as increased IL-6 and plasma cortisol, but decreased amounts of cAMP responsive element binding protein and brain-derived neurotrophic factor (BDNF), which is very similar to what is observed in people with depression and mood disorders that exhibit a wide range of cognitive problems (Song et al., 2006[114]). The gene discussed is BDNF; the disease is depressive symptom measurement.