Prediction and Pathophysiology of Poststroke Depression

Sir, We read the article "Risk Factors and Functional Outcome of Ischemic Stroke vis-à-vis Hemorrhagic Stroke at a Tertiary Care Hospital in North India" in the esteemed "Journal of Marine Medical Society" with great interest.1 Gupta et al. prospectively studied the risk factor stratification for stroke patients. They observed that hypertension is the major risk factor for hemorrhagic and ischemic strokes. Furthermore, individuals who developed intracranial hemorrhage have a worse prognosis regarding their functionality within 3 months of the episode.1 Poststroke depression is the most common noncognitive neuropsychiatric complication after stroke, affecting approximately 33% (95% confidence interval CI: 29%–36%) of stroke survivors.2 The Diagnostic Statistical Manual of Mental Disorders-5 lists poststroke depression as a depressive disorder due to an underlying medical condition, explaining that the pathophysiology of poststroke depression is a consequence of another disease.2 Interestingly, the pathophysiology of poststroke depression involves five main hypotheses: lesion location, decreased neurogenesis, immune dysfunction, neurotransmitter dysfunction, and increased cortisol levels Figure 1.1-5 It is worth mentioning that a previous history or a family history of any neuropsychiatric disorder could influence the etiology of depression after a stroke.3,5 Herein, we would like to discuss the current literature on poststroke depression.Figure 1: Pathophysiology of poststroke depression. ACTH: Adrenocorticotropic hormone, BDNF: Brain-derived neurotrophic factor, HPA: Hypothalamic–pituitary–adrenocortical, IFN: Interferon, IL: Interleukin, NT: Neurotransmitter, TNF: Tumor necrosis factor, VEGF: Vascular endothelial growth factorHomocysteine may cause abnormalities of central monoamine neurotransmitters and the hypothalamic–pituitary–adrenocortical axis, which can be associated with depression.3 Chen et al. systematically reviewed the literature to assess whether homocysteine levels in the acute phase of stroke are associated with poststroke depression.3 They found that homocysteine levels were significantly higher (standardized root mean square difference = 0.37, 95% CI = 0.07–0.66) in poststroke depression individuals than in controls.3 The findings of this meta-analysis suggest that homocysteine is an independent predictor of poststroke depression.3 Risk factors of poststroke depression are multifactorial and complex, including the severity and location of the stroke, social support, and individual characteristics.4 Some authors believe that C-reactive protein is closely related to depression.5 In this way, Yang et al. systematically reviewed the literature to evaluate the association between the C-reactive protein level in the acute phase of stroke and the risk of poststroke depression.4 The authors found that, at admission, C-reactive protein levels were significantly higher (standardized root mean square difference = 0.19, 95% CI: 0.12–0.27) in poststroke individuals than in control.4 Noteworthy, C-reactive protein levels were already associated with stroke severity.4 In this way, assessing possible confounding factors of the studies is challenging.4 Identifying blood biomarkers can improve the accuracy of poststroke depression diagnosis and facilitate early intervention.3 Qiu et al. studied the association of biomarkers with poststroke depression 3 months after a minor stroke.5 They found a difference in biomarkers among the male and female sex.5 Fibrinogen was more commonly associated with the male sex.5 On the other hand, free triiodothyronine, magnesium, and brain-derived neurotrophic factors were more frequently abnormal in the female sex.5 These results suggest different pathophysiologies according to sex, which should be carefully assessed regarding screening, diagnosis, and treatment of poststroke depression.5 Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.