credit: Clinical Advisor
Lewy body dementia is an umbrella term that includes two disorders — dementia with Lewy bodies and Parkinson’s disease dementia. Using the “one year rule,” doctors diagnose someone with Parkinson’s disease dementia (PDD) if dementia and hallucinations occur a year or more after the onset of motor symptoms (or Parkinson’s disease). Doctors diagnose dementia with Lewy bodies (DLB) when dementia, visual hallucinations, and motor symptoms occur concurrently or if dementia or hallucinations precede motor symptoms.
The publication “Clinical Advisor” features dementia with Lewy bodies (DLB) in its current educational offering for physicians. This online article is worth checking out.
The article notes:
“Most estimates suggest that DLB accounts for 3% to 7% of dementia diagnoses. DLB is more prevalent than PDD, making it the most common subtype of LBD.”
It’s surprising that the prevalence number is tiny and that DLB is more prevalent than PDD. Since a million people with Parkinson’s disease live in the US and half of those will develop dementia, I would’ve thought that the prevalence of PDD would’ve been higher.
Another surprising point is:
“DLB is considered a sporadic disorder. However, genetic factors have been identified in 60% of cases. … Risk increases substantially in individuals with a first-degree relative who has DLB, including a 2-fold increase if a sibling is affected. Depression and rapid eye movement sleep behavior disorder (RBD), characterized by acting out dreams through excessive extremity movement and shouting, are recognized risk factors.”
I had no idea that genetic factors played such a large role in DLB. No doubt the genetic factors are SNCA and APOE mutations.
The article notes that DLB can be confused with Alzheimer’s disease (AD), PDD, vascular dementia, normal pressure hydrocephalus (NPH), delirium, and other Parkinsonian disorders, such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal syndrome.
Indeed, in Brain Support Network’s efforts with helping families accomplish brain donation, we see the Lewy body dementia is not always confirmed upon death. What’s often thought to be LBD turns out to be AD, NPH, or PSP. And, what’s often thought to be MSA, turns out to be LBD! (Let Brain Support Network assist your family with brain donation so that you may receive a confirmed diagnosis and contribute to research.)
Brain Support Network has had a few cases (one very recent case) where a neurologist diagnosed LBD but the confirmed diagnosis turned out to be NPH, upon brain donation. The “Clinical Advisor” had this to say about the differential diagnosis of NPH:
“The classic gait disturbance is described [in NPH] as a magnetic gait, because the feet appear to be stuck to the floor during ambulation. This may be confused with a Parkinsonian gait. Imaging shows enlarged ventricles without significant brain atrophy.”
The article addresses symptomatic treatment, including medications, physical therapy, and cognitive behavioral therapy. Finally, the article discusses complications (such as agitation, aspiration pneumonia, and falls) and prognosis (“average survival time of 6 years” after diagnosis).
(You may have to register to view the article. Registration is free.)
Some of the language will be challenging!
Robin
Brain Support Network