 There has been much speculation concerning Barrett 's psychological well @-@ being . His family have denied that he suffered from mental illness , ( despite displaying an almost textbook case of schizophrenia ) , but in a 2016 interview , his sister <unk> Breen said that his mind was brilliant , bordering on that seen in <unk> Syndrome . Barrett 's use of psychedelic drugs , especially LSD , during the 1960s is well documented , and there were theories he subsequently suffered from schizophrenia . Rick Wright asserts that Syd 's problems stemmed from a massive overdose of acid , as the change in his personality and behavior came on quite suddenly . However , Roger Waters maintains that Syd suffered " without a doubt " from schizophrenia and in an article published in 2006 , in response to notions that Barrett 's problems came from the drug , and Gilmour was quoted as saying : 
