METHODS	Severity of CI was measured using the Cognitive Performance Scale ( CPS ) and categorized into 4 groups : None/Mild ( CPS = 0-1 , MMSE = 22-25 ) , Moderate ( CPS = 2-3 , MMSE = 15-19 ) , Severe ( CPS = 4-5 , MMSE = 5-7 ) and Very Severe ( CPS = 6 , MMSE = 0-4 ) .\