Can strokes cause mental illness regardless of age?

Mental illness?: What do you mean by "mental illness"? Schizophrenia? Bipolar disorder? Please define your terms. Strokes cause COGNITIVE deficits which vary depending on affected hemisphere. They can cause personality changes but this is rare. They can cause psychosis but this is ALWAYS transient (hours or days). They can definitely cause mood changes (depression or euphoria) but that's not really "illness."

See below: Mental illness is not directly caused by stroke. Stroke can cause problems such as personality changes, decreased memory and decreased ability to communicate, among others. These changes caused by stroke can be confused with a mental illness. Depression is common after a stroke.