This chapter explores the associations of mental illness and substance abuse that are risk factors for suicide in the United States and Europe. The first section of this chapter discusses suicide risk associated with mental and/or addictive disorders and what is known about who among those with these disorders is at greatest risk. Suicides in adolescents appear to be associated with a somewhat different set of variables, as discussed in a separate section. Next, the chapter explores psychological variables, including protective factors: those associated with reduced risk for suicide. Certain psychological factors distinguish and predict those who complete or attempt suicide. These include habits of thinking, problem solving, and expectations about the future, termed cognitive style or factors. These factors are modifiable through counseling and training, and their modification holds promise in reducing suicide. Finally, the chapter turns to temperament. Temperament has a significant genetic component (Goldsmith and Lemery, 2000) that interacts with environmental adversities to increase vulnerability to a number of unwanted outcomes, including suicide.

Almost all psychiatric disorders, including alcohol and substance disorders, are associated with an increased risk of suicide. Depressive disorders are found in 30–90 percent of those who complete suicide, including the approximately 5 percent with bipolar disorder (Lönnqvist, 2000). Approximately another 5 percent are associated with schizophrenia (De Hert and Peuskens, 2000), 30 percent with a personality disorder (Davis et al., 1999; Henriksson et al., 1993; Isometsa et al., 1996), and 25 percent with alcohol abuse disorders (Murphy, 2000). Anxiety disorders including post-traumatic stress disorder (PTSD) are associated with approximately 20 percent of suicides (Allgulander, 2000). As many as 10 percent of those who complete suicide do not have a known psychiatric diagnosis. Around 20–25 percent of individuals who die by suicide are intoxicated with alcohol at death (see section on Alcohol Use below). Many individuals have multiple diagnoses concurrently, and comorbidity may in and of itself increase risk (Kessler et al., 1999), although there are little data on this issue, in part due to the hierarchical nature of the current psychiatric diagnostic system, in which mood and psychotic disorders are more heavily considered.

Diagnoses associated with suicide attempts present a similar profile. Though there may be distinctions between sub-types of attempters and completers, they appear to be generally overlapping populations; current data do not allow resolution of this issue. This differentiation is further