P2RX4 and depressive disorder: Numerous risk factors for the development of post-stroke depression have been identified, including female gender, a personal history of depression [10] or mental illness, the presence of other important comorbidities (for example diabetes, low vitamin D) [11,12], certain localizations of the stroke, low socioeconomic status, the existence of a spouse [13], inability to return to work [14], Latino ethnicity [15], increased stress response [16], smoking [17], P2X4R deletion [18] and the severity of neurological impairment.