Prevalence of Mental Illness

Methodologies adopted by the Center for Mental Health Services (CMHS), the federal agency with mental health oversight responsibilities, provide the tools used to estimate the overall prevalence of mental illness in Alaska. In 1997, the CMHS published methods for identifying the portion of each state's total population of adults experiencing serious mental illness (SMI) and of children experiencing serious emotional disturbance (SED).

The key questions in assessing the applicability of the CMHS approaches were two. First, how does CMHS define Serious Mental Illness and Serious Emotional Disturbance? Second, how does CMHS count those it defines as experiencing Seriously Mentally Ill and Seriously Emotionally Disturbed?

CMHS defines children with serious emotional disturbance as persons:

From birth up to age 18, who currently or at any time during the past year have had a diagnosable mental, behavioral, or emotional disorder of sufficient duration to meet DSM diagnostic criteria that resulted in functional impairment substantially interfering with or limiting the child's role or functioning in family, school, or community activities.

CMHS defines functional impairments as difficulties that substantially interfere with or limit a child or adolescent from achieving or maintaining one or more developmentally-appropriate social, behavioral, cognitive, communicative, or adaptive skills. The definition includes functional impairments of episodic, recurrent, and continuous duration unless these are temporary and expected responses to stressful events.

The CMHS definition of Serious Mental Illness essentially mirrors its Serious Emotional Disturbance definition except that it applies to persons age 18 and over.

CMHS reviewed epidemiological research from across the United States (relatively little such research has been done nationwide and none in Alaska). With this research as its basis, CMHS teams of experts developed overall estimates of Serious Mental Illness and Serious Emotional Disturbance prevalence. For Serious Mental Illness prevalence, the CMHS team identified a number of demographic and socio-economic factors associated with mental illness. Those factors were applied to produce Serious Mental Illness estimates for every state. CMHS estimated the Alaskan Serious Mental Illness rate at 6.3% of the household population (which excludes institutional and homeless populations), seventh highest in the nation.

For children and youth, CMHS does not estimate state by state Serious Emotional Disturbance prevalence. Instead the agency posits an Serious Emotional Disturbance range of 9%-13% of children age 9-17, based on a substantial functional impairment (compared to a range of 5%-9% for those with an extreme functional impairment). An individual state's placement within this range depends upon that state's poverty rate.

The CMHS methodology complicates determining Alaska's Serious Emotional Disturbance overall prevalence. First, CMHS only estimates the Serious Emotional Disturbance rate for ages 9-17, citing insufficient evidence for estimating prevalence in younger children. The simple approach is to assume the 9-17 Serious Emotional Disturbance rate roughly reflects the rate for children age 8 and under. Alaska's low statewide poverty rate, suggests that our Serious Emotional Disturbance prevalence should be toward the lower end of the range, but the higher cost of living mitigates that. In our judgment, a 10% prevalence balances those two considerations. Unfortunately, the extant research did not allow CMHS to consider other factors, such as substance abuse rates or cultural diversity, in prevalence calculations. Our 10% figure accords with a 1993 study by Norman Dinges on Serious Emotional Disturbance prevalence in Alaska which found that "the public mental health sector will have to provide services for approximately 10% of the school age youth."

Serious Mental Illness and Serious Emotional Disturbance prevalences provide the tools to tally the number of Alaskans with Serious Mental Illness or Serious Emotional Disturbance. Table 1 on the next page displays the results of those calculations (to the nearest hundred). In 1997, we estimate that about 44,500 Alaskans had a serious mental illness or serious emotional disturbance. Some did so for the first time, but many have had chronic illness for a large part of their lives. This 44,500 includes 14,700 children (10% of the age 5 to 18 population) and 25,600 adults (6.3% of the 19 and over population). Estimates of the Serious Mental Illness/Serious Emotional Disturbance segment of institutional and homeless populations originate from several sources and add up to 4,200 individuals.

1997 Prevalence of SMI/SED in Alaska

Table 1

Absent Alaskan epidemiology, these prevalence estimates represent the best available information. But view the numbers with some caution for the reasons discussed below.

· Serious Emotional Disturbance and Serious Mental Illness estimates may mask higher prevalence rates in rural Alaska. Lower socioeconomic status strongly associates with mental and emotional disorders. Other indicators, such as substance abuse and suicide rates, also suggest that prevalence, particularly among children, may be underestimated in rural Alaska.

· Alaska's urban population is increasing as a share of the state's population. Urban population density is a valid predictor of serious mental illness among adults and Alaska can look for added upward pressure on prevalence rates as its urban population continues to grow. CMHS estimates Anchorage, Fairbanks, and Juneau Serious Mental Illness rates to be higher than the statewide figure of 6.3%.

· Age is an important factor in mental illness; younger people are more likely to suffer mental illness, which CMHS estimates for Alaska take into account. However, Alaska's Native and black populations are both substantially younger than Alaska's population at large and thus at greater risk.

· A 1997 study estimates that 5,000 to 6,000 Alaskans have organic brain syndrome (OBS); many are without appropriate services.