'The DNA sequence of genes for someone with an illness like schizophrenia and for someone without a mental illness often look the same; there are no visible changes that explain the cause of a disease,' Dr. Arturas Petronis, a senior scientist at Krembil Family Epigenetics Laboratory at the Centre for Addiction and Mental Health, said in a release.

'But we now have tools that show us changes in the second code, the epigenetic code.'

The Toronto-based study, published in the March 3 edition of the American Journal of Human Genetics, identified a second genetic code of epigenetic changes — chemical changes to a gene that do not alter the DNA sequence — in individuals with the psychoses. These changes can trigger under-production or overproduction of the body's proteins, changing its functions.

The researchers found evidence of total or partial silencing of genes responsible for communication with the brain, brain development and other processes linked to schizophrenia and bipolar disorder. 

The Schizophrenia Society of Canada estimates 300,000 people in the country are affected by the disorder, which is characterized by delusions, hallucinations and drastic changes in mood.
Bipolar disorder causes severe changes in mood and energy. The Canadian Psychiatric Association estimates that 500,000 Canadians suffer from the condition.