Tau-PET and Aβ-PET correlations with atrophy progression were similar in both groups (Alzheimer's disease: rtau-PET = −0.44 versus rAβ-PET = −0.35, P-value = 0.11; FHAD: rtau-PET = −0.05 versus rAβ-PET = 0.06, P-value = 0.10), while tau-PET had a higher correlation with atrophy at baseline, compared with Aβ-PET, only in Alzheimer's disease (Alzheimer's disease: rtau-PET = 0.36 versus rAβ-PET = 0.23, P-value = 0.03; FHAD: rtau-PET = 0.38 versus rAβ-PET = 0.34, P-value = 0.49). The gene discussed is MAPT; the disease is Atrophy.