Depression and Mood Disorders

Depression and Mood Disorders
The Prevalence of Major Depression and Mood Disorders in Suicide

Mental Health: A Report of the Surgeon General, states that "major depressive disorders account for about 20 to 35 percent of all deaths by suicide" (p. 244). This estimate is based on a review of psychological autopsies conducted by Angst, Angst, and Stassen (1999). This brief review is intended to address this prevalence estimate. It is important to note that this estimate refers only to the prevalence of major depressive disorder among those who commit suicide, not any other mood disorders (e.g., bipolar I & II, dysthymia, adjustment disorder with depressed mood). Prevalence estimates that include other mood disorders in addition to major depression are much higher.

Major depression in suicide
The lower bound of the 20-35% estimate of the prevalence of major depression in suicide is loosely based on one psychological autopsy study; a study where the reliability of the diagnoses are somewhat questionable. This study (Rich, Young & Fowler, 1986) of 204 subjects identified 15% of suicides as having major depressive disorder. However, an additional 30% were reported as having "atypical depression," defined in this study as having a depressive syndrome that followed the onset of substance use. If this ambiguously defined group were to be considered major depression, the estimate climbs to 45%. A number of other studies suggest that the prevalence of major depression in suicide is somewhat over 30%. The four other available psychological autopsy studies that include samples of suicides from the full age range and reliable diagnoses based on structured interviews (Arato, Demeter, Rihmer & Somogyi, 1988; Dorpat & Ripley, 1960; Foster, Gillespie, McClelland & Patterson, 1999; Henriksson et al., 1993) obtained prevalence estimates of major depression ranging from 30-34% of suicides. In addition, several psychological autopsy studies examining more specific subsamples (e.g., the elderly, adolescents, women) find even higher prevalence estimates. In three psychological autopsy studies of adolescents (Brent et al. 1988; Brent et al., 1999; Shaffer et al., 1996) 41%, 43%, and 32% of adolescent suicides were determined to have had major depression prior to death. Two studies of young adults (Lesage et al. 1994; Runeson, 1989) found a prevalence of 40% and 41%, respectively. A study of 104 women by Asgard (1990) found a 35% rate of major depression. One study of 54 older adults over age 65 found a prevalence of 54%. In summary, the available data suggest that the 20-35% estimate for the prevalence of major depressive disorder in completed suicide is probably somewhat conservative and that a 30-40% prevalence estimate is probably more accurate. This estimate includes both secondary and primary depression. Many of these individuals would also be comorbid with other disorders, especially substance abuse.

Mood disorders in suicide
Prevalence estimates for all mood disorders in suicide (including MDD, Bipolar I & II, dysthymia, and adjustment disorder with depressed mood) are much higher than for major depression alone. These rates are probably closer to 60%, although as noted below, this estimate varies because of inconsistency of the criteria used to define a "mood disorder" across investigations. Four studies examining the full age range of suicides estimate that 36%, 48%, and 66%, and 70% of suicides have some sort of "depressive disorder" or "depression" (Foster et al., 1999; Rich et al., 1986, Henriksson et al., 1993, Barraclough, Bunch, Nelson, & Sainsbury, 1974). Three studies of adolescents found prevalence estimates for "mood disorders" or "affective disorders" of 61%, 63%, and 67% respectively (Shaffer et al., 1996; Brent et al. 1988; Marttunen et al., 1992). Two studies of young adults (Lesage et al., 1994; Runeson, 1989) found estimates of 60% and 64%. A study of 104 women by Asgard (1990) found a 59% rate of "mood disorders." In a review of psychological autopsy studies that examined patterns of psychiatric diagnosis across age groups, Conwell and Brent (1995) concluded that depressive disorders increased with age. Overall estimates for the rates of mood disorders range from 36% to 70% with great interstudy variability. This variability is probably partly a combination of unreliable methods of diagnosis and different definitions of what constitutes a "mood disorder." Despite this variability, a number of studies have found a pattern for increasing mood disorders with aging.