On the basis of the patient's history and presentation, the likely diagnosis is Alzheimer's disease (AD). It is the most common cause of dementia. In some cases, MCI can be a clinical precursor of AD. MCI is characterized by minor difficulties in functional ability and neurocognitive dysfunction, but not to the degree experienced with dementia. This patient's increasing difficulties with independent daily functioning are suggestive of an AD diagnosis.
Patients with Parkinson's disease often have a substantial reduction in olfactory function by the time motor signs emerge, and forgetfulness can accompany early Parkinson's disease. However, there is no report of motor signs in this patient. Typical early motor signs of Parkinson's disease include tremor, bradykinesia, rigidity, and dystonia.
Elderly individuals may develop mild vascular cognitive impairment, but this tends to occur more abruptly, rather than the slowly progressing memory loss experienced by the case patient and associated with AD. Patients with mild vascular cognitive impairment experience cognitive decline that is worse than expected for their age and educational level; however, the decline in cognitive function in this patient does not meet the National Institute on Aging-Alzheimer's Association criteria for dementia, and daily functional living skills are within normal limits. Acute or subacute cognitive impairment after an acute neurologic event, accompanied by a stepwise progression, is a common presentation in vascular dementia.
Lewy body dementia is unlikely to be relevant in this case. Clinical features that help to distinguish Lewy body dementia from AD typically include:
Fluctuating cognitive function with varying levels of alertness and attention (eg, excessive daytime drowsiness despite adequate nighttime sleep or daytime sleep > 2 hours, staring into space for long periods, episodes of disorganized speech)
Visual hallucinations
Parkinsonian motor features
Relatively early extrapyramidal features (in contrast, these may occur late in AD)
Anterograde memory loss: May be less prominent (in contrast, this is a prominent early sign in AD)
More prominent executive function deficits and visuospatial impairment (eg, Stroop effect, digit span backward)
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Cite this: Jasvinder P. Chawla. Skill Checkup: A 70-Year-Old Woman With History of Depression and Mild Cognitive Impairment Presents With Memory Lapses - Medscape - Dec 22, 2022.
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