High and low testosterone levels may be associated with suicidal behavior in young and older men,respectively

Testosterone, an androgen hormone, regulates male sexual development, and influences muscle size, levels of red blood cells, bone density, a sense of well-being, mood, cognition, and sexual and reproductive function. Some observations suggest that suicidal behavior may be related to blood levels of testosterone (Sher, 2012; Sher et al., 2012). For example, we observed that testosterone levels correlate with the number of suicide attempts in patients with bipolar disorder (Sher et al., 2012). A connection between testosterone and suicidal behavior may be related to (Sher, 2012):

• a direct influence of testosterone on suicidality;

• testosterone influencing aggression and, consequently, suicidality;

• testosterone influencing mood and, consequently, suicidality; and

• testosterone influencing cognition and, consequently, suicidality.

At least one study directly suggested that higher testosterone levels are associated with suicide in young adults (Roland et al., 1986). In young men, aggressive behavior is probably associated with high testosterone levels (Roland et al., 1986; Sher, 2012; Sher et al., 2012). For example, it has been observed that, in adolescent males, higher testosterone levels were associated with provoked verbal and physical aggression, which suggests that impulsive aggression correlates with higher testosterone levels (Sher, 2012; Sher et al., 2012). There are considerable similarities between aggression against the self and aggression against others (Sher, 2012; Sher et al., 2012). Our studies have shown that high aggressiveness is associated with suicidal behavior (Sher et al., 2012). For example, we have observed that high aggression predicts suicidal acts (Sher, 2012). Therefore, aggression may medicate the effect of high testosterone levels on suicidal behavior in adolescents and young adults.

Testosterone deficiency is a widely recognized hormonal alteration associated with male aging. In older people, depressed mood and impaired cognition are associated with decreased testosterone levels (Amore et al., 2012; Chu et al., 2010; Sher, 2012; Sher et al., 2012). Older men with a testosterone deficiency frequently have depressive symptoms, and depressed men often have lower blood testosterone levels compared to non-depressed individuals (Amore et al., 2012; Sher, 2012; Sher et al., 2012). Also, hypogonadal men frequently display lower cognitive abilities compared to men with normal testosterone levels (Sher, 2012; Sher et al., 2012). It has been reported that higher blood levels of testosterone in older men are associated with a lower risk of future Alzheimer’s disease development (Chu et al., 2010). Several research groups also observed that low blood testosterone levels are associated with Alzheimer’s disease (Chu et al., 2010). Both depression and cognitive impairment are associated with suicidal behavior (Sher, 2012; Sher et al., 2012). Hence, depression and cognitive impairment may medicate the effect of testosterone deficiency on suicidality in older men. This suggests that the treatment of hypogonadism in older men may improve mood and cognition, and consequently, reduce suicidal behavior.

In summary, it is reasonable to propose that suicidal behavior in young men is associated with high testosterone levels, while suicidality in older men is associated with decreased testosterone secretion. This indicates that the effects of testosterone on suicidality in men should be studied separately in young and older individuals.