Final answer:
The sudden, step-wise decrease in cognitive function in a 78-year-old female suggests Vascular dementia or Multi-infarct dementia, as these conditions are associated with sudden cognitive decline due to vascular events, whereas Alzheimer's disease and Lewy body dementia typically present with more gradual onset symptoms.
Step-by-step explanation:
A 78-year-old female presenting with memory loss and a sudden, step-wise decrease in memory/cognition is likely experiencing a form of dementia. The key descriptor here is the 'step-wise' decrease in cognitive function, which points to Vascular dementia or Multi-infarct dementia, both of which are characterized by a sudden decline in cognitive ability resulting from cerebrovascular events such as strokes. Alzheimer's disease is a more gradual decline rather than step-wise and would not typically present with the sudden changes described. Lewy body dementia is associated with symptoms such as slowed movements, balance and posture problems, which are not the primary concern in the scenario given.
Alzheimer's disease, first studied by medical researcher Solomon Carter Fuller, was named for Alois Alzheimer, a German psychiatrist who reported amyloid plaques and neurofibrillary tangles in a patient's brain. However, since the patient in question has experienced a step-wise decline in cognition, Alzheimer's disease is less likely, and the diagnosis would more aptly fit the profile of Vascular dementia or Multi-infarct dementia, which are causes of abrupt neurological changes due to vascular problems in the brain.