Purpose

Differentiating between Alzheimer’s disease (AD), vascular dementia (VaD), and mixed dementia (MD) remains a major clinical challenge, as overlapping symptoms and comorbid pathologies limit the diagnostic value of screening tools. The Addenbrooke’s Cognitive Examination III (ACE-III) offers a multidomain assessment and may support differential diagnosis.

Methods

The study included 138 Polish patients with mild dementia (46 AD, 46 VaD, 46 MD), matched for age, sex, and education, and diagnosed based on current clinical criteria. Group comparisons were conducted using the Kruskal-Wallis test with Dunn- Bonferroni post hoc analyses.

Results

Total ACE-III scores did not differ significantly between the groups. Significant effects were observed only in the Memory domain, where VaD patients scored higher than both AD and MD, who did not differ from each other. Subtest analyses confirmed group differences in episodic memory tasks. Only Serial 7 Subtraction (Attention) and Letter Fluency differentiated between groups, with AD patients outperforming VaD patients. Within the Visuospatial domain, only Dot Counting differentiated between groups (AD > MD > VaD). The Language domain showed no group effects.

Conclusions

While total ACE-III scores have limited diagnostic value, domain- and subtest-level analyses reveal distinct cognitive profiles supporting differential diagnosis. VaD is marked by preserved episodic memory but impaired attention and executive tasks, AD by severe episodic memory deficits, and MD by an AD-like profile with vascular contributions. Domain-focused interpretation of ACE-III may enhance diagnostic accuracy in clinical practice.