Dementia with Lewy Bodies (DLB), Dementia with Lewy bodies vs Alzheimer’s Disease vs Parkinson’s Disease

Dementia with Lewy Bodies (DLB) is a neurodegenerative disease, classically presented with progressive cognitive impairment, parkinsonism, visual hallucinations, and fluctuations in attention and confusion. Key neuropathologic feature is the present of alpha-synuclein aggregrates (known as the Lewy Bodies) which are found in the brainstem and often in limbic and neocortical region. These Lewy bodies are composed of epitopes detected by antibodies against non-phosporylated and also phosporylated neurofilament proteins, ubiquitin, and the pre-synaptic protein, alpha-synuclein. Unfortunately, such Lewy Bodies is also present in substantia nigra of Parkinson’s Disease (PD), and also found in “Lewy body variant of Alzheimer’s Disease (AD)”, thus, quantifying Lewy Bodies to differentiate among these is difficult and remain controversial. However, current consensus criteria suggest that DLB is the cause of dementia when Lewy bodies are present in the regions beyond brainstem and with absent, low, or only intermediate level of pathological changes that represent AD.

It’s presentation has to be differentiated between PD and AD, and it is often difficult. Patient of DLB has presentation somewhat lies between or combination of both PD and AD. Yet, differentiating among them clinically is not impossible. Often, victims of DLB has dementia comparable to AD, but more severe in visuospatial function and visual memory. Visuospatial task such as object size discrimination, form/shape discrimination, overlaying object discrimination and visual counting is more significantly affected than AD. DLB patient also has a rather unique presentation; the day to day fluctuation of cognitive impairment and attention. DLB victims, also has visual hallucination, however such hallucination is non-threatening and often patient has insight about it.

Parkinsonism is also another features of DLB, but compared to PD, it is mild and presented later than dementia. As compared to PD, which has parkinsonism has prominent feature and dementia came later. Generally, dementia presented less than 1 year after the onset of parkinsonism should suspect DLB, and if dementia is more than 1 year after the onset of parkinsonism would point towards PD. Below table summarize the comparison.

20130104-155823.jpg

The role of neuroimaging is yet remain obscure and requires more studies validation. However, FDG-PET has showed patterns of reduced occipital metabolism in
patients with DLB compared with patients with AD, with sensitivity and specificity of 90% and 80% respectively. Image shows FDG-PET of patient with DLB. image obtained from [ref4].

20130104-162223.jpg

References
1. Elizabeth Finger, Kirk R. Daffner. Cognitive and Behavioral Neurology. In: Burneo, Jorge G; Demaerschalk, Bart M.; Jenkins, Mary E. eds. Neurology: an evidence-based approach. New York, NY: Springer; 2012:161-174

2. Andrew J. Larner, Alasdair J. Coles, Neil J. Scolding, Roger A. Barker. A-Z of Neurological Practice A Guide to Clinical Neurology. New York, NY: Springer; 2011:176-178

3. Thomas D. Bird and Bruce L. Miller. Alzheimer’s disease and other dementia. In: Stephen L. Hauser eds. Harrison’s Neurology in clinical practice. New York, NY: McGraw-Hill; 2010:313-314

4. Benjamin Franc. Imaging dementia with PET-CT. Clinical Faculty University of California, San Francisco

About these ads

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s