sentence: Memory problems are frequently the first subjective cognitive complaint in Parkinson ’ s disease ( Noe et al ., 2004 ) and are a prominent component of PD dementia ( Whittington et al ., 2000 ; Bronnick et al ., 2007 ; Muslimovic et al ., 2007 ; Reid et al ., 2011 ; Wang et al ., 2015 ) , forming part of the diagnostic criteria for PD dementia ( Emre et al ., 2007 ) .