Are we over estimating cognitive impairment in patients who have a Primary Progressive Aphasia Diagnosis - Is the MOCA appropriate?

Abstract Background Cognitive ability has been shown to be associated with functional ability1. Primary Progressive Aphasia (PPA) is a subtype of dementia characterised by early language impairment, which may not fully reflect broader cognitive or functional decline.2 The Montreal Cognitive Assessment (MOCA), widely used in dementia assessment, is language-heavy and may underestimate functional ability in individuals with PPA. Methods We retrospectively analysed data from 26 patients attending our Integrated Care clinic. Six were diagnosed with PPA; the remaining 20 had Alzheimer’s disease, Lewy Body Dementia, Vascular Dementia, or Mild Cognitive Impairment (MCI). Standardised measures included the MOCA, Barthel Index (basic activities of daily living), Lawton-Brody scale (instrumental activities of daily living), and Clinical Frailty Scale (CFS). We used Mann-Whitney U tests to compare cognitive and functional scores between groups and Spearman correlations to explore associations between MOCA and functional measures. Results PPA patients scored lower on the MOCA (median 13.5) compared to non-PPA patients (median 19), though not statistically significant (U = 24.5, p = 0.118). Despite this, Barthel and Lawton-Brody scores remained high in the PPA group, with a trend toward higher Lawton scores (U = 96.5, p = 0.084). Spearman correlation analysis showed no significant correlation between MOCA scores and functional measures in either group. Conclusion Patients with PPA may demonstrate significant language-related cognitive impairment without corresponding declines in functional independence. Our findings suggest that reliance on MOCA alone may potentially underestimate cognitive abilities in PPA, highlighting the need for multimodal assessment in this population.