This patient's subacute onset dementia and prominent memory issues with lack of concern point towards pseudodementia (dementia 2/2 MDD). She also meets criteria for MDD with flat affect, sleep changes, appetite changes, psychomotor retardation, concentration problems (repeating 3 numbers in sequence)

• Differential for dementia in elderly patient includes: Alzheimer’s (chronic neurodegenerative course), Vascular dementia (patient with ASCVD risk factors with stepwise decline), Frontotemporal dementia (early personality changes often around 60 yo), Dementia with Lewy bodies (parkinsonism, visual hallucinations, fluctuating cognition), Normal pressure hydrocephalus (“wet, wacky and wobbly”) and pseudodementias (depression, hypothyroidism, B12 deficiency)
• In this patient with acute/subacute forgetfulness along with components of SIGECAPS (trouble sleeping, decreased appetite, psychomotor retardation) and history of past episodes of forgetfulness that were able to be treated with medication most consistent with a major depressive disorder episode
• Key idea: Alzheimer’s can also lead to signs/symptoms similar to Major depressive disorder, but Alzheimer’s would have a chronic progressive course rather than an episodic course as is seen in this question stem