Dementia with Lewy Bodies
What is Dementia with Lewy Bodies?
Dementia with Lewy Bodies (DLB) is a neurodegenerative disorder characterized by cognitive decline, visual hallucinations, and parkinsonian features. It’s one of the common causes of dementia in older adults, and it shares some similarities with both Parkinson’s disease and Alzheimer’s disease. DLB is associated with the abnormal accumulation of alpha-synuclein and Lewy bodies in the brain.
Key features of DLB include:
- Fluctuating cognition: People with DLB often experience rapid changes in attention and alertness.
- Visual hallucinations: These are a hallmark symptom, and they typically involve seeing things that aren’t present.
- Parkinsonism: Motor symptoms like bradykinesia, rigidity, and tremors are common.
- REM sleep behavior disorder: Individuals with DLB often exhibit vivid, physically active dreams during REM (rapid eye movement) sleep.
- Autonomic dysfunction: This can manifest as changes in blood pressure, heart rate, and digestion.
Dementia with Lewy bodies (DLB) can sometimes be difficult to distinguish from Parkinson’s disease with dementia (PDD).
Typically, DLB is faster in progression, less responsive to levodopa, and associated with visual hallucinations and fluctuations in the level of alertness. Another distinguishing point is that in DLB, the memory loss precedes the parkinsonism or begins around the same time, whereas in PDD, the parkinsonism typically precedes the memory loss by several years. One symptom seen most commonly with DLB (but also in PD) is REM sleep behavior disorder (RBD), in which there is an absence of the usual paralysis during dream sleep (rapid eye movement REM), resulting in acting out dreams.
Diagnosis of DLB
Typically the diagnosis is based on the clinical examination, neuropsychological evaluation, and response to medication. MRI is done to exclude other causes of dementia and parkinsonism such as stroke, but there are no diagnostic findings on MRI that reliably distinguish DLB from related conditions. DaTscan and FDG-PET can distinguish between Alzheimer’s disease (the most common cause of dementia) and DLB / PDD, but there are no functional image tests that can reliably distinguish between DLB and PDD.
Treatment of DLB
Treatment for Dementia with Lewy Bodies is mainly supportive, meaning medications for cognition, parkinsonism and hallucinations, but these medications tend to provide only modest, and often short-lived, benefit for DLB. Physical therapy can be helpful as well. Avoidance of neuroleptics (antipsychotics) such as haloperidol (Haldol), risperidone (Risperdal), aripiprazole (Abilify), olanzapine (Zyprexa), prochlorperazine (Compazine), metoclopramide (Reglan) is key because of the higher risk of adverse effects in patients with DLB.