Population: total number of patients and healthy controls considered in the study. Method: quantitative method applied in the study. Cohort investigated: number of patients considered for sensitivity and specificity estimations. Followup: duration of observational period (for early diagnosis study). Sensitivity and specificity: results of the study. LHR+: likelihood ratio. Increase in the LHR+: increase in the probability of the likelihood of the disease. GRADE: results of GRADE evaluation. Quality of evidence was evaluated based on LHR+ values, LHR+ increase probability, and size of the sample included. Abbreviations: AD: Alzheimer’s disease; FTD: frontotemporal dementia; MCI: mild cognitive impairment; ODD: other dementia; LBD: Lewy body dementia; VaD: vascular dementia; HC: healthy controls.