chemically imbalanced vs unhinged

chemically imbalanced

adj
  • Mentally ill. 

  • Used other than figuratively or idiomatically: see chemically, imbalanced. 

unhinged

adj
  • Mentally ill or unstable. 

  • Not having ever been mounted using a stamp hinge. 

  • Not furnished with a hinge. 

How often have the words chemically imbalanced and unhinged occurred in a corpus of books? (source: Google Ngram Viewer )