Experts in treating mental illness said it remains difficult to understand and will cost the state more money and more lives if not treated.
The testimony came during the first meeting Wednesday of a new bipartisan Assembly task force examining mental health issues.
Experts in the field said one out of four people in Wisconsin is associated with certain types of mental illness such as paranoia and depression. They said that could expand to half of the state's residents.
Experts said the complexity of mental illness has left it underestimated and underfunded.
Republican Assembly Speaker Robin Vos created the task force to study mental health issues in Wisconsin and if they are related to violence.