Dementia Types

Which pathological hallmark is most characteristic of Alzheimer's disease and is composed of phosphorylated tau protein?

A 68-year-old man from Delhi presents with a 3-year history of progressive memory loss, difficulty with word-finding, and recurrent episodes of getting lost in familiar places. His wife reports he has become withdrawn and apathetic. On examination, he is oriented to person and place but not to date. Mini-Cog score is 2/3. Brain MRI shows hippocampal atrophy and generalized cortical atrophy predominantly in the temporal and parietal lobes. CSF biomarkers show decreased amyloid-β42, elevated phosphorylated tau, and elevated total tau. Which is the most likely diagnosis?

A 72-year-old woman from Mumbai presents with a 2-year history of progressive behavioral changes. Her family reports she has become socially inappropriate, disinhibited, and emotionally blunted. She frequently uses profanities and makes crude jokes. Memory is relatively preserved early on, though she is now developing some forgetfulness. She shows poor judgment and has spent large sums on unnecessary items. On examination, she has hyperreflexia and an exaggerated jaw jerk. MRI shows marked frontal and anterior temporal lobe atrophy with relative sparing of the hippocampus. Which is the most likely diagnosis?

Which dementia type is characterized by the presence of Lewy bodies in the cortex and is associated with visual hallucinations and parkinsonian features?