<prompt> A 70 yr old man presents with 10 prosopagnosia loss of memory, 3rd person hallucination for 1 month. On examination deep Tendon reflexes are increased, mini-mental examination score is 2030. What is most likely diagnosis:Dissociated DementiaSchizophreniaAlzheimers diseasePsychotic disorder  <response>: C i.e. Alzheimers diseaseDuration of 1 month only, is enough to rule out schizophrenia, in which duration should be at least 6 monthsIn psychiatric disorders like schizophrenia psychosis, there may never be organic symptoms like increased tendon reflexes.Features of Alzheimer dementia areMemory impairment without impairment of consciousnessAnosognosia Unaware of his problem Prosopagnosia difficulty in identifying known facesFocal neurological signs ex asymmetrical hyperreflexia or weaknessPrimitive reflexes ex grasp, snout, suck, Palmo-mental, tonic foot reflexesFrontal lobe signsAphasia language disturbanceApraxia impaired ability to carry out motor activities despite intact motor functionAgnosia failure to recognize or identify objects despite intact sensory functionDisturbance in executive functioning i.e. planning, organizing, sequencing, abstracting 