The present invention provides compositions and methods for treating cognitive impairment or dysfunction in a subject. In particular, the present invention provides a method for using a composition comprising an angiotensin-(1-7) receptor agonist to treat cognitive dysfunction or impairment that is due to a various clinical conditions including, but not limited to, those associated with increase in inflammation, cytokine production, increases in reactive oxygen species, changes in expression of brain inflammatory related genes and/or in the expression of genes involved in learning and memory within the central nervous system of a subject.