This article reviews the general diagnostic criteria for dementia and then reviews the diagnostic criteria for several specific types of dementia, including AD, FTD, VaD, MCI, DLB, and PDD.
This article describes DLB as "one of a few conditions in which dementia is associated with extrapyramidal features." However, in another article I recently read, "The Potential of Gait Analysis to Contribute to Differential Diagnosis of Early Stage Dementia," the authors suggested that *many* dementias were associated with extrapyramidal features and that the use of this term is ineffective because there's not a widely recognized definition of it.
"Extrapyramidal" refers to movement-related symptoms. As a local support group member pointed out during a recent get-together, the presence of movement-related or parkinsonian symptoms is NOT required for an LBD diagnosis. I had to keep this in mind when I read the section on DLB in this article.
At the same gathering, another local support group member pointed out that one neurologist she met with said that her mother could not have LBD because her mother had no tremor!
What follows are some excerpts from the DLB and PDD sections, and then the article abstract (which you can find on pubmed.gov).
Excerpts from DLB section:
"The time when the dementia, the extrapyramidal syndrome development and the psychiatric features appear in the course of the disease, is the basis for the differential diagnosis of the dementias with Parkinsonism"
"There is no consensus regarding the delay between the onset of parkinsonian features in DLB and the appearance of cognitive deficit. The recent 2005 consensus on DLB recommends arbitrarily a one year delay between motor parkinsonism and dementia though this concept of delay is still evolving."
DLB is "considered the second most frequent degenerative disease causing dementia, though this statement is controversial. The prevalence is reported as being 5-20% depending on the study population and setting. Patients may be misdiagnosed or under diagnosed compared to AD."
In the recent 2005 consensus on DLB, "the authors raised questions around the difficulty of appropriately characterizing and quantifying the fluctuation and the hallucinations with some suggestions for methods to improve clinical assessments. ... Furthermore, they have reclassified supportive features in two categories; 'suggestive features' are based on the frequency of occurrence compared to other dementia syndromes and 'supportive features' on the common occurrence but lower specificity. The 'suggestive features' include REM sleep behavior disorder, severe neuroleptic sensitivity and 'low dopamine transporter (DAT) uptake in basal ganglia' on functional imaging. ... Remaining supportive features include myocardial scintigraphy and EEG."
"These revised 2005 DLB criteria are a step forward to better define DLB and hopefully improve diagnostic sensitivity."
Robin's note: The LBDA's website has a good description of this diagnostic criteria at:
Though I see that myocardial scintigraphy and EEG are not listed.
Excerpts from PDD section:
"Unfortunately, there are no validated standard clinical or research criteria for the diagnosis of PDD which currently hinges on the later development of dementia in a patient with Parkinson's disease. The cognitive profile and the time when the extrapyramidal syndrome appears are important in this...differential diagnosis. Early bilateral extrapyramidal symptoms (without predominance of tremor) associated with early cognitive decline and behaviour problem would favour DLB. Classic PD with unilateral symptoms at the onset and which is present for a few years before the appearance of cognitive decline would favour PDD, although there is no consensus on the number of years required. Based on the arbitrary one-year window for DLB criteria, a delay beyond one year would suggest PDD. ... On the other hand, some cognitive decline has been documented well before the definite diagnosis of dementia in early PD. It may be difficult to draw a strict line between DLB and PDD when the delay parkinsonian features-cognitive deficit is short in these two diseases with a neuropathological continuum."
"Dementia is frequent in advanced PD, and with age. The overall prevalence of dementia in PD ranges between nearly 30% in a community-based study to about 40%. In an older clinicopathological study, up to 45% of patients with PDD have been shown to have some Alzheimer pathology while more recent studies have identified more predominant synucleinopathy with the dementia."
"The main other features of PDD include attention deficits, fluctuation, memory retrieval problems, impaired executive functions, impaired verbal fluency and personality changes. Contrary to DLB and PDD, the extrapyramidal syndrome in AD, mainly bradykinesia and rigidity, rarely tremor, occurs late in the course, is usually bilateral."
Robin's note: I think that last sentence is not well-written because to me it means that DLB and PDD are not usually bilateral but AD is usually bilateral. Yet, earlier in the PDD section, the authors state: "Early bilateral extrapyramidal symptoms (without predominance of tremor)...would favour DLB. Classic PD with unilateral symptoms at the onset...would favour PDD..."
Robin's note: This article just noted that the "extrapyramidal syndrome" occurs late in AD. But "The Potential of Gait Analysis...." article I mentioned earlier reviews studies that have conflicting results. In one study, the authors (Pettersson et al, 2002) conclude that gait impairments are evident in early AD.
Here's the abstract (see pubmed.gov for this abstract online):
The Canadian Journal of Neurological Sciences. 2007 Mar;34 Suppl 1:S11-8.
Diagnostic criteria of dementia.
Clinique de mÃ©moire et unitÃ© de recherche Alzheimer, CHA HÃ´pital de I'Enfant-JÃ©sus, QuÃ©bec, QC, Canada.
In the past two decades there has been a tremendous effort among clinicians and searchers to improve the diagnostic criteria of the dementias on the basis of the differential neurological and neuropsychological profiles. This was an obligatory requirement for clinical trials and the development of treatments. Over the years it became rapidly evident that the cohorts of patients in studies had some degree of heterogeneity, making it difficult to interpret the results of some studies, particularly in the vascular dementias and the mild cognitive impairment (MCI) group. For example, many sub-types of the vascular group were included in clinical trials, such as the cortical strokes, the lacunar states and the diffuse white matter disease cases, and some of the patients might have had also mixed pathology. In addition, the standard DSM IV criteria for dementia no longer represent our present knowledge of the clinical profile of some of the dementias such as vascular dementia (VaD) and fronto-temporal dementia where the memory impairment is not necessarily the first requirement. To improve the validity of clinical trials and eventually help developing more appropriate treatments, we revised the present diagnostic criteria and made recommendations for some changes in the context of the 2nd Canadian Conference on the Development of Antidementia Therapies, held in 2004 and reviewed in the light of the recent literature as of early 2006. It is expected that in the near future, these dementia criteria for clinical trials will have to be revised again in order to include specific subtypes of the dementias as well as biomarkers, structural and functional imaging.
PubMed ID#: 17469675