Objective To report derivation of subscores from the Montreal Cognitive Assessment (MoCA) analogous to those derived from MMSE (MoCA Ala score) and Addenbrooke's Cognitive Examination (MoCA VLOM ratio) and examine their utility in differential diagnosis of Alzheimer's disease (AD) from dementia with Lewy bodies (DLB) and frontotemporal lobar degeneration (FTLD) respectively.

Results Of 150 patients administered the MoCA (Int Psychogeriatr 2012;24:391–6), subscores were calculated for those with target diagnoses. MoCA Ala subscores did not differ significantly between AD and DLB (t=1.13, df=25, p>0.1). At the specified Ala subscore cutoff of <5, MoCA Ala subscore was neither sensitive (0.60) nor specific (0.59) for diagnosis. MoCA VLOM ratio at cutoff <1 was sensitive for a diagnosis of FTLD (0.89); cutoff ≥0.67 was sensitive for a diagnosis of AD (0.77).

Conclusions In this preliminary study, based on a pragmatic diagnostic accuracy study of MoCA, MoCA Ala subscore was not helpful in differentiating DLB and AD, but MoCA VLOM ratio was useful in differentiating FTLD and AD. It will be interesting to examine the utility of these MoCA subscores in larger patient cohorts.