The clinical workshop adopted a two-stage approach to the challenging task of agreeing clinical diagnostic criteria for dementia with Lewy bodies (DLB).

Session one – Where does DLB fit within the diagnostic framework?

The first step was to define the scope of the new criteria, in particular whether they ought to be part of a unifying diagnostic category covering the whole spectrum of clinical presentations of LB disorders, or whether they should restrict themselves to only one part of this. The subsequent task would then be to select and operationally define the specific items of diagnostic importance. Two existing sets of clinical diagnostic criteria (the Newcastle criteria for senile dementia of Lewy body type (SDLT) (McKeith et al., 1992) and the Nottingham criteria for dementia associated with cortical Lewy bodies (Byrne et al., 1991)) were tabled for consideration, as were supplementary data from other participants (all to be found in the preceding clinical chapters).

Preliminary discussion centred on the principle that diagnostic criteria should be framed in the way most relevant to established clinical procedures. It was agreed that a single set of clinical criteria encompassing the whole spectrum of LB disorders, ranging from motor Parkinson's disease (PD) to primary cognitive failure, would produce a diagnostic category containing enormous clinical heterogeneity. Such a system would be difficult to apply in clinical practice and would have low face validity.