Severity of CI was measured using the Cognitive Performance Scale ( CPS ) and categorized into @ groups : None/Mild ( CPS = @-@ , MMSE = @-@ ) , Moderate ( CPS = @-@ , MMSE = @-@ ) , Severe ( CPS = @-@ , MMSE = @-@ ) and Very Severe ( CPS = @ , MMSE = @-@ ) .