A report by the University of California, Los Angeles, Center for Health Policy Research said 2 million Californians -- about 8 percent of the population -- report mental health needs but most receive little or no treatment.
Lead author David Grant said the study used data from the 2007 California Health Interview Survey, which found about one-quarter who reported serious psychological distress received "inadequate" treatment -- defined as less than four visits with a health professional over the past 12 months or using prescription drugs to manage mental health needs.
"There is a huge gap between needing help and getting help," Grant said in a statement. "The data also show large disparities in mental health status and treatment by demographic, economic and social factors. These findings can help direct the state's limited resources to those in greatest need of help."
Uninsured adults had the highest rate of unmet needs at 87 percent. Sixty-six percent of that group received no treatment, while others received less than minimally adequate treatment.
In contrast, 77 percent of privately insured and 65 percent of publicly insured Californians reported unmet mental health needs.
Although poverty and mental health needs are strongly correlated, the lower rate of unmet needs by public program participants suggests that these programs are more likely to effectively offer mental health services than even private insurance policies, Grant said.