A man who was in the throws of a psychotic episode when he beheaded a fellow Greyhound bus passenger has received an absolute discharge from the Criminal Code Review Board.

The move means Will Baker, formerly known as Vince Li, is no longer subject to any monitoring. Baker has been receiving treatment for schizophrenia since being found not criminally responsible in the death of Tim McLean. Baker's condition is a complex one that experts say is not always well understood.

Here are a few facts about schizophrenia:

What is it?

Experts say schizophrenia, which literally means separated from reality, is a blanket term given to a family of mental illnesses. Dr. David Bloom, chief of the psychotic disorders program at Montreal's Douglas Institute, likens the variety of schizophrenias to the various types of cancer that exist. Bloom says not all causes are known, but  elevated dopamine levels in the brain are directly involved in most.

How common is it?

The Centre for Addiction and Mental Health says about one per cent of the population has the disease. Schizophrenia affects men and women equally, although symptoms tend to manifest themselves in men somewhat earlier 芒鈧珺次元官网网址� in their teens and 20s.

What are the key symptoms?

Symptoms tend to be consistent across the various types of schizophrenia, experts say. The Centre for Addiction and Mental Health says there are two categories of symptoms 芒鈧珺次元官网网址� positive and negative. People showing positive symptoms can experience delusions, hallucinations and disorganized thoughts. Negative symptoms include lack of motivation, loss of interest in the feelings of others and reduced physical activity.

Is there a cure?

Experts agree no cure has been found, but some say medical advances can help keep the condition under control and allow people to lead full lives. They stress, however, that timely treatment is important.

What are the available treatments?

"Three-quarters of the patients will do quite well on quite standard anti-psychotic medications," says Bloom, who adds most of those work by lowering or blocking dopamine in the brain. There are some schizophrenic patients who do not respond to such treatments because their dopamine levels are in check. Patients are also urged to tap into other treatments such as cognitive behaviour therapy and psycho-educational services. Bloom says forgoing psychological services is akin to undergoing a successful hip replacement but declining to follow up with physiotherapy.

Are there side effects?

Bloom says anti-psychotic medication can have very serious side effects that deter people from continuing treatment. These vary by medication but can include feeling sedated, mentally sluggish or "dead inside." Physical symptoms also include tremors and muscle cramps, as well as sexual side effects.

Can patients stop their medication safely?

Not in most cases. Bloom compares schizophrenics to diabetics who are dependent on insulin for life. "For a schizophrenic-type illness, the chances of relapse are, not perhaps 100 per cent, but pretty close to 100 per cent."

Michelle McQuigge, The Canadian Press