ABSTRACTBackground:Assigning a diagnosis to a patient with dementia is important for the present treatment of the patient and caregivers, and scientific research. Nowadays, the dementia diagnostic criteria are based on clinical information regarding medical, history, physical examination, neuropsychological tests, and supplementary exams and, therefore, subject to variability through time.Methods:A retrospective observational study to evaluate variables related to clinical diagnostic stability in dementia syndromes in at least one year follow up. From a sample of 432 patients, from a single university center, data were collected regarding sociodemographic aspects, Clinical Dementia Rating, physical examination, neuropsychological tests, and supplementary exams including a depression triage scale.Results:From this sample, 113 (26.6%) patients have their diagnosis changed, most of them adding a vascular component to initial diagnosis or depression as comorbidity or main disease. Our findings show that many factors influence the diagnostic stability including the presence of symmetric Parkinsonism, initial diagnosis of vascular dementia, presence of diabetes and hypertension, the presence of long term memory deficit in the neuropsychological evaluation, and normal neuroimaging. We discuss our findings with previous findings in the literature.Conclusion:Every step of the clinical diagnosis including history, vascular comorbidities and depression, physical examination, neuropsychological battery, and neuroimaging were relevant to diagnosis accuracy.