A complex assortment of factors may put a person at risk for committing suicide. Age, gender, social status and even ethnic background all play a role. People over the age of 65 years, for instance, are more likely to commit suicide than any other age group. Women are at a greater risk of attempting suicide, while men have a greater risk of dying by suicide.

The most significant risk factor for suicide is untreated depression. According to the National Mental Health Association, between 30 and 70 percent of people who committed suicide suffered from major depression or bipolar disorder. People with other mental disorders (e.g., anxiety disorders) are also at higher risk for suicide.

Many mental disorders that increase the risk of suicide are interrelated. For instance, substance abuse often coexists with depression, and both are risk factors for suicidal thoughts or behavior. According to the National Institute of Mental Health (NIMH), more than 90 percent of people who committed suicide suffered from depression or another mental disorder at the time of their deaths.

Biochemical factors may increase the risk of suicide. The level of certain neurotransmitters in a person’s brain have been linked to both suicidal behavior and depression. Low levels of serotonin have been detected in people who committed or attempted suicide.  Since serotonin helps control impulsivity, a decrease in the amount of serotonin in a person’s brain may increase the risk of suicide. It may also increase the risk of depression, which can include suicidal thoughts or behavior. There is still uncertainty whether the changes in neurotransmitters cause these disorders, or reflect the presence of the disorders.

Genetics also plays a role, since suicide appears to run in families. Those with a family history of suicidal behavior are at greater risk of suicidal behavior. However, since suicide is so closely linked to a number of different mental disorders that have a genetic component, it is unclear whether it is the suicidal behavior or accompanying disorder that may be genetic.

Medical conditions can increase a person’s risk of suicide. Any physical illness that involves chronic pain or is terminal can lead to depression, which can include suicidal thoughts or behavior. These include medical conditions such as heart disease, stroke, cancer, HIV/AIDS, diabetes and Parkinson’s disease. In addition, depressive symptoms can be a side effect of various medications or a result of viral infections, thyroid disorders and low testosterone levels (in men).

A number of social or environmental factors can increase a person’s risk of suicide. These include high stress, easy access to lethal means (e.g., firearms in the home, access to potentially lethal medications or poisons) and recent loss (e.g., divorce, job, relationship, status, self-esteem). For youth, these risk factors also include physical/sexual abuse, a history of family violence and exposure to the suicide of others (contagion). For older adults, common environmental risk factors include the death of a spouse, retirement or loss of independence (e.g., moving into a nursing home).

Also closely linked to the risk of suicide are previous suicide attempts, a history of suicidal thoughts or behavior, impulsive or aggressive behavior and a lack of involvement in school, work or social activities. A history of suicide attempts appears to be the best indicator of future suicide attempts. About 50 percent of successful suicides have at least one attempt in their background. Secondary risk factors include stress and social isolation, feelings of hopelessness or vulnerability, being easily overwhelmed by stress, and/or low self-esteem.