Revision of assessment toolkits for improving the diagnosis of Lewy body dementia: The DIAMOND Lewy study.

As part of the UK National Institute for Health Research DIAMOND Lewy Programme (improving the DIagnosis And Management Of Neurodegenerative Dementia of Lewy body type), we have reported in this journal the development of two assessment toolkits to assist in the recognition and diagnosis of Lewy body dementia.1 The “Assessment Toolkit for Dementia with Lewy Bodies” is for use by clinicians in memory and dementia services; the “Assessment Toolkit for Lewy Body Dementia,” which facilitates an accurate diagnosis of either Parkinson's disease (PD) dementia or dementia with Lewy bodies, is designed for clinicians in movement disorder and geriatric medicine services.

The toolkits were developed to be easy to use by clinicians and to align with consensus diagnostic criteria for these dementias. Since our report appeared, the Fourth Consensus Report of the DLB consortium on the diagnosis and management of DLB has been published.2 We have therefore updated our toolkits to align them with the new criteria and here summarise these changes. The link below takes you to our original paper, where the development of these toolkits is described (http://onlinelibrary.wiley.com/doi/10.1002/gps.4609/full) and which is free to download. The revised toolkits are in the Appendices to this Editorial.

CHANGES IN DLB DIAGNOSTIC CRITERIA

Diagnosis of DLB according to previous 2005 criteria relied on the identification of core features of DLB (fluctuating cognition, recurrent complex visual hallucinations, and one or more spontaneous cardinal features of parkinsonism) and suggestive features (REM sleep behaviour disorder [RBD], neuroleptic sensitivity, and abnormal striatal dopaminergic imaging). The two main changes in the Fourth Consensus Report are (1) to upgrade RBD to become the fourth core clinical diagnostic feature and (2) to restructure the criteria so suggestive features no longer appear, but are replaced with “indicative biomarkers” and “supportive features.”

CORE FEATURES

RBD is a parasomnia in which movements and vocalisations occur during REM sleep (dream reenactments) because of the absence of normal REM atonia. The assessment toolkits recommend use of a specific validated question to identify RBD clinically. Where there is doubt about RBD, polysomnography (PSG) should be considered. The presence of two core clinical features is necessary to diagnose probable DLB whilst one alone enables a possible DLB diagnosis.

Less prominent than the upgrading of RBD, but helpful and important, is further clarification on parkinsonism. Whilst this has generally been understood to exclude drug‐related and vascular parkinsonism, it has been less clear which and how many motor features of PD are required. PD requires the presence of bradykinesia (slowness of movement and decrement in amplitude or speed) together with rest tremor or rigidity or both.3 The Fourth Report specifies that for counting as a core clinical feature for DLB, only one of these three features is sufficient. Special care is necessary when assessing older people or those with comorbidities, eg, osteoarthritis, or with advanced dementia because these features may be misinterpreted in such situations. For example, stiffness due to arthritis, or apraxia related to cognitive impairment, may mimic bradykinesia. In such situations, a dopaminergic scan should be considered. This leads to the other noticeable change in these revised diagnostic criteria, namely, the emphasis on biomarkers.

INDICATIVE BIOMARKERS

In the previous Third Consensus Report, low dopamine uptake in the striatum on dopaminergic imaging was a suggestive feature of DLB. In the Fourth Report, this is joined (under the new category of indicative biomarkers) by abnormal (low uptake) cardiac MIBG (123‐iodine‐MIBG myocardial scintigraphy) imaging and PSG evidence of REM sleep without atonia. Abnormal MIBG imaging results from the reduction in noradrenergic innervation of the myocardium in Lewy body diseases4 whilst PSG demonstrating REM sleep without atonia is the validated standard test for RBD.5 The presence of any one of these in someone with dementia together with a core feature allows the diagnosis of probable DLB. Abnormal biomarker evidence, even more than one, in the absence of a core clinical feature only enables a possible DLB diagnosis. Those familiar with the Third Report will notice that of the three suggestive features in those criteria (abnormal dopaminergic imaging, RBD, and severe neuroleptic sensitivity), neuroleptic sensitivity has been “downgraded” to a supportive clinical feature as “severe sensitivity to antipsychotic agents.” This may be regarded as a good thing in that it reflects the greatly reduced use of antipsychotics in people with dementia generally and in those likely to have DLB in particular, with recent research reporting no study subjects having this feature (eg, Walker et al6 and Donaghy et al7).

We have amended the toolkits to align with the new DLB criteria, to maximise ease of use and utility. Clinicians experienced in the diagnosis of DLB may not need to routinely use these toolkits for all patients, but our earlier study1 found clinicians greatly valued the detail these toolkits provided about how to efficiently elicit the key features of DLB in everyday clinical practice. This was especially true for less experienced or trainee clinicians, and their routine use should serve as a useful training experience to heighten awareness of DLB symptoms and how to apply the new DLB diagnostic criteria.