Pseudodementia caused by severe depression.

The diagnosis of pseudodementia may be difficult in a patient with a history of major depressive disorder. Clinical case history. A 70-year-old man with a history of major depressive disorder, in remission for 3 years, presented with confusion, agitation and cognitive disorder. The differential diagnosis included depression with pseudodementia, drug-induced dementia or Alzheimer disease. Mild cognitive improvement was noted after discontinuation of simvastatin. After 9 months of treatment for depression, the patient had remission that was sustained for >1 year, with mild residual difficulty remembering words of songs. The differential diagnosis of dementia includes major depressive disorder and adverse events from simvastatin.