WA State Specific Fact Sheets:
Prevalence of Serious Mental Illness in Washington
The 2001, the Washington State Legislature requested “a study of the prevalence of mental illness among the state’s regional support networks”. This study was completed in 2003 and provides regional detail on the most recent estimates of adult serious mental illness in Washington. This study found:
There were 189,070 cases of serious mental illness among WA State Adults, which represents 4.33% of the total adult population. However, among low-income adults (below 200% of the federal poverty level), there were 84,833 cases of serious mental illness or 8.54% of the total low income population.
WA State’s community mental health services are overseen by regional support networks (RSN) made up of one or more contiguous counties. The table below illustrates the share of serious mental illness prevalence by RSN. In 2003, of the 4.4 million adults who lived in Washington, 31 percent were from King County. Of the estimated 189,070 adults with serious mental illness in WA, 60,030 (32%) resided in King County. Across each RSN, the total share of adult serious mental illness corresponds closely to the share of the overall adult population.
RSN Share of Serious Mental Illness Prevalence (Adults) in Washington State
Regional Support Network |
Adult Population (share) |
Adult SMI Estimate (Share) |
Adults under 200% FPL SMI Estimate (Share) |
Chelan/ Douglas |
70,891 (2%) |
2,978 (2%) |
1,710 (2%) |
Clark |
246,253 (6%) |
10,519 (6%) |
4,435 (5%) |
Grays Harbor |
49,943 (1%) |
2,178 (1%) |
1,178 (1%) |
Greater Columbia |
427,105 (10%) |
17,376 (9%) |
9,658 (11%) |
King |
1,346,388 (31%) |
60,630 (32%) |
22,988 (27%) |
North Central |
140,333 (3%) |
5,961 (3%) |
3,602 (4%) |
North Sound |
707,046 (16%) |
28,805 (15%) |
11,638 (14%) |
Peninsula |
241,075 (6%) |
9,875 (5%) |
4,500 (5%) |
Pierce |
510,251 (12%) |
22,790 (12%) |
10,584 (12%) |
Southwest |
68,043 (2%) |
2,948 (2%) |
1,468 (2%) |
Spokane |
310,439 (7%) |
14,724 (8%) |
7,887 (9%) |
Thurston/ Mason |
192,614 (4%) |
7,963 (4%) |
3,554 (4%) |
Timberlands |
69,807 (2%) |
2,816 (1%) |
1,489 (2%) |
State total |
4,380,278 (100%) |
189,070 (100%) |
84,833 (100%) |
Source: Washington State Department of Social and Health Services (2003).
