chemically imbalanced vs unhealthy

chemically imbalanced

adj
  • Mentally ill. 

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

unhealthy

adj
  • characterized by disturbed mental health 

  • characterized by, or conducive to poor health 

  • tending to corrupt 

  • sick or ill 

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