What is the most likely diagnosis for a 65-year-old woman experiencing distress over believing she died 3 months ago?

The most likely diagnosis for a 65-year-old woman believing she died three months ago is psychotic depression. This condition is characterized by the presence of depressive symptoms, including low mood, loss of interest, and feelings of worthlessness, accompanied by psychotic features such as delusions or hallucinations. The belief that one has died is a type of delusion, specifically a nihilistic delusion, which can manifest in major depressive episodes, especially in elderly patients.

In this scenario, the woman's strong distress about her perceived death indicates a significant disruption in her perception of reality, which aligns with the characteristics of psychotic depression.

While the other options could involve various forms of distress or altered perceptions, they do not specifically account for the combination of depressive symptoms with a firm belief in having died. Generalized anxiety disorder primarily involves excessive worry and anxiety, not delusional beliefs; schizophrenia typically involves a broader range of symptoms, including disorganized thinking and a variety of delusions, but the specific context here points less toward classic schizophrenia. Bipolar disorder may involve mood changes and could include depressive episodes, but the overt delusional aspect of believing one is dead is more closely associated with psychotic depression.