According to the data presented in the previous study (F. G. Pajonk et al., 2010), and using the statistical significant level 0.05 and the power 0.80, we calculated the sample size for cognitive assessment is 96 (32 each arm) and for brain imaging the sample required will be 48 (16 each arm) (Noordzij et al., 2010). Considering the drop-out rate will be around 30%, we aim to recruit 120 patients (40 each arm) with half of them (20 each arm) undergoing MRI scanning.