- All patients meeting the clinical criteria underwent brain magnetic resonance imaging (MRI) scan including hippocampal assessment at screening. The MRI entry criteria are as follows: the number of cerebral infarcts (≥20 mm in diameter)less than 2, without infarcts in thalamus, hippocampal or entorhinal cortex, the medial temporal lobe atrophy visual rating scale (MTA) score more than 2 degree.