The cause of muscle dysmorphia is not clear. The NHS states it may be genetic or caused by a chemical imbalance in the brain.

For Dillon, it seems to encompass everything from frank delusion to psychosomatic symptoms to psychological responses to organic illness, taking in depression and body dysmorphia along the way.

Considering that depression can cause poor self-esteem and sometimes even body dysmorphia, it's also possible that depressed teens would self-report "substantial" acne more often than their peers.