The combination of reduced Aβ42 and increased t-tau and p-tau levels is collectively termed ‘an AD-like profile’ considering its specificity for diagnosing the condition.122 This profile occurs in a larger proportion of synucleinopathy patients with prominent cognitive dysfunction, i.e. Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB).123–125 CSF AD-like biomarkers may, therefore, be useful for differentiating DLB from other parkinsonian disorders, although for some interventional trials this distinction may be somewhat arbitrary. This evidence concerns the gene MAPT and Alzheimer disease.