Memory-sparing cognitive deterioration in the elderly: what is the diagnosis?

The case presented highlights the difficult differential diagnosis of memory-sparing cognitive decline in an elderly patient with previously stable bipolar illness. Many disorders can contribute to cognitive and behavioral deterioration in this population, including reversible causes, particularly delirium and psychiatric illness, and irreversible structural or progressive processes including vascular disease, dementia with Lewy bodies, normal-pressure hydrocephalus, and frontotemporal dementia.