demented vs not right in the head

demented

adj

  • Crazy; ridiculous. 

  • Insane or mentally ill. 

  • a demented idea 

  • Suffering from dementia. 

not right in the head

adj

  • crazy, insane 

How often have the words demented and not right in the head occurred in a corpus of books? (source: Google Ngram Viewer )