Fast Five Quiz: Alzheimer's Disease Differential Diagnosis and Workup

Jasvinder P. Chawla, MD, MBA; Shaheen E. Lakhan, MD, PhD, MS, MEd


September 12, 2023

Two types of dementia that can be memory-sparing are dementia with Lewy bodies (DLB) and vascular dementia. The following clinical features help to distinguish DLB from Alzheimer's disease:

  • Patients with DLB often experience fluctuations in cognitive function, with varying levels of alertness and attention (eg, excessive daytime drowsiness despite adequate nighttime sleep or daytime sleep > 2 h, staring into space for long periods, or episodes of disorganized speech).

  • Visual hallucinations occur in patients with DLB but are uncommon in patients with Alzheimer's disease.

  • Spontaneous parkinsonian motor features are typical in early stages of DLB compared with later disease onset of Alzheimer's disease.

  • Patients with DLB experience a relatively early onset of extrapyramidal features compared with patients with Alzheimer's disease.

  • Patients with DLB experience less prominent anterograde memory loss, compared with its prominent early emergence as an early sign of Alzheimer's disease.

  • More prominent executive function deficits and visuospatial impairment (eg, the Stroop effect or digit span backward) are seen in patients with DLB compared with patients with Alzheimer's disease.

Vascular dementia, the second most common form of dementia, produces focal or diffuse effects on the brain that result in cognitive decline. Fortunately, vascular disease is preventable; therefore, early recognition and treatment are important to prevent and slow disease progression. Hypertension is the most common cause of vascular dementia.

Both Alzheimer's disease and FTD (of which primary progressive aphasia and frontal lobe dementia are major aspects) result in profound memory loss. However, unlike Alzheimer's disease, FTD initially presents as gradually worsening aphasia over several years; patients eventually exhibit progressive dementia.

Although chronic traumatic encephalopathy (CTE) and FTD both result in profound memory loss, CTE results from repeated concussions and closed head injuries in athletes. Repeated headaches, aggression, and progressive dementia are typical signs of CTE. Unlike Alzheimer's disease, the hippocampus of patients with CTE does not exhibit volume loss.

Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive neurodegenerative disorder that affects 1 in 1 million people per year. There is no known cure for CJD, and treatment is supportive. Most patients die within 1 year of symptom onset.

Learn more about the clinical presentation of Alzheimer's disease.


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