Depression is a common and often serious problem occurring in stroke patients. Inflammatory hormones, known as cytokines, are stimulated by an activated immune system and sometimes become active following a stroke. They may be responsible for altering levels of key neurotransmitters and their metabolites in the blood and brain of stroke patients. The investigators' objective is to examine whether increased cytokine activity following a stroke may be the cause of an increased presence or severity of depression or cognitive impairment among stroke patients, as a result of tryptophan depletion and/or kynurenine activation. They are recruiting patients within one month of their strokes and measuring levels of key markers in their blood. Patients are assessed for the presence of depressive and/or cognitive symptoms and treated with an antidepressant if needed. The investigators expect to show that cytokine activation is related to depression and/or cognitive impairment among stroke patients.