Fast Five Quiz: Alzheimer Disease Differential Diagnosis and Workup

Jasvinder P. Chawla, MD, MBA

Disclosures

May 23, 2019

Two types of dementia that can be memory-sparing are DLB and vascular dementia.

The following clinical features help to distinguish DLB from Alzheimer 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 hours, staring into space for long periods, episodes of disorganized speech).

  • Visual hallucinations occur in up to 80% of patients with DLB but are fairly rare in patients with Alzheimer disease.

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

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

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

  • More prominent executive function deficits and visuospatial impairment (eg, the Stroop effect, digit span backward) are seen in patients with DLB compared with patients with Alzheimer 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 disease and FTD (of which primary progressive aphasia and frontal lobe dementia are major aspects) result in profound memory loss. However, unlike Alzheimer disease, FTD initially presents as gradually worsening aphasia over several years; patients eventually exhibit progressive dementia.

Although 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 signs of CTE. Unlike Alzheimer disease, the hippocampus of patients with CTE does not exhibit volume loss.

CJD is a rare, rapidly progressive neurodegenerative disorder that affects 1 in 1,000,000 people worldwide. There is no known cure for CJD, and treatment is supportive. Most patients die within 1 year of diagnosis.

For more on the clinical presentation of Alzheimer disease, read here.

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