Key Words Dementia · Depression · Differential diagnosis · Addenbrooke’s Cognitive Examination

Background/Aims: Dementia and depression are different clinical conditions, but share com-mon features, and can be indistinguishable in the initial disease stages. We aimed to establish whether the Peruvian version of the Addenbrooke’s Cognitive Examination (ACE-Peru) can distinguish between the cognitive profile in patients with incipient dementia and that in pa-tients with depression. Methods: This was a cross-sectional study to assess the performance on the ACE-Peru of 193 elderly subjects (102 with dementia, 21 with depression, and 70 healthy controls). Depending on the diagnosis, there were two groups of cognitive impair-ment (CI) – the primary neurodegenerative (PN-CI) subtype and the secondary to depression (SD-CI) subtype – as well as a non-CI group. The area under the curve (AUC) of the receiver-operating characteristic curve was determined to compare the diagnostic performance, using the diagnosis of CI as the gold standard. Results: In our sample of elderly subjects aged 59–82 years with at least 7 years of education, the ACE-Peru showed a significantly better performance than the MMSE (AUC = 0.997 vs. AUC = 0.887; p < 0.05) for the discrimination between PN-CI and SD-CI. Conclusions: The ACE-Peru is able to distinguish between the cognitive profile in patients with incipient dementia and that in patients with depression