Objective: Attention is the cardinal feature of delirium, but attentional domains may also be affected by dementia and its severity. It is, therefore, of interest to study the correlation between the severity of cognitive impairment in non-delirious patients and different measurements of attentional performance, to identify attention subdomains less affected by severity of cognitive impairment. Methods: Neuropsychological data from non-delirious outpatients (age ≥ 65 years), presenting at two memory clinics were analysed retrospectively. Scores for selective, divided, and sustained attention were correlated with cognitive impairment as defined by the score of the Mini-Mental State Examination. Results: A total of 1658 outpatients were included. The mean age was 77.15 (± 8.17) years, with a mean MMSE score of 22.67 (± 4.91). Compared to the type of attention, the tests that are less influenced by the severity of cognitive impairment are those of selective attention, in particular the Digit Span Forward (DSF). Conclusions: This is the first study to correlate deficits in attention subdomains with the degree of cognitive impairment in non-delirious patients. The results suggest that measurements of selective attention (i.e. DSF) might be better suited to discriminate delirium from dementia. Indeed, a lower score on these tests might be indicative of an acute change and worsening of the baseline inattention and a longitudinal monitoring of these changes might be used to determine the delirium resolution.
