People who inject drugs have a particularly high risk of suicide when they also use stimulants such as cocaine and amphetamines, a team of Canadian researchers says. Injection drug users have relatively strong chances of developing diagnosable problems with substance abuse\/addiction. They also have elevated chances of making suicide attempts and actually committing suicide. In a study published in late 2014 in the journal Drug and Alcohol Dependence, a team of Canadian researchers examined the impact of various forms of additional substance intake on the odds that injection drug users will make suicide attempts. Injection Drug Use People who inject illicit drugs rely on a hypodermic needle and a syringe to rapidly introduce any one of an array of substances into their bloodstreams. Avenues of injection include the veins that carry blood from the body to the heart, muscle tissue and the area just beneath the layers of the skin. Types of substances introduced through one or more of these avenues include heroin and chemically related opioid medications such as oxycodone or hydrocodone, the stimulant drug cocaine and the stimulants amphetamine and methamphetamine. In addition to producing an effect on the brain faster than other methods of substance intake, injection drug use can produce more intense changes inside the brain for any given quantity of a substance. Because of its greater impact on brain function, injection drug use is well-known for its ability to trigger the fairly quick onset of substance abuse and\/or substance addiction (known collectively as substance use disorder). Additional risks associated with the practice include blood vessel damage from fillers and contaminants contained within the drugs\/medications and exposure to a range of infectious microorganisms as a result of unsanitary injection techniques. Specific types of infection associated with injection drug use include HIV, hepatitis C, localized skin abscesses and system-wide blood poisoning. Substance Use and Suicide People with diagnosable cases of substance use disorder attempt suicide almost 500 percent more often than the general U.S. population. Depending on the gender of the person affected by various forms of this disorder, the rate of actual completed suicide ranges from roughly 100 percent to more than 500 percent above the national average. Many of the underlying risks for suicide found in the general population also apply to people dealing with diagnosable substance problems. In addition, repeated and excessive substance use can lead to changes in mental health that create further risks. People who use certain types of substances or certain combinations of substances may have particularly high chances of making suicide attempts. Impact of Additional Substance Intake In the study published in Drug and Alcohol Dependence, researchers from the University of Montreal and two other Canadian universities used a project involving 1,240 adults to explore the impact of additional forms of substance intake on the suicide risks of people who consume injection drugs. All of the study participants were known injection drug users. Each individual detailed his or her habitual or occasional non-injection use of six substances: alcohol, marijuana\/cannabis, opioid drugs or medications, sedative-hypnotic medications (including tranquilizers) and the stimulants cocaine and amphetamine. In addition, each participant detailed his or her history of suicide attempts in the half-year period prior to the start of the study. When the study began, 5.7 percent of the participants reported making a recent suicide attempt. Over the course of the study, another 11.5 percent of the participants reported making such an attempt. After analyzing patterns of non-injection substance intake, the researchers concluded that the consumption of three substances\u2014cocaine, amphetamine and sedative-hypnotic medications\u2014significantly increases the odds that an injection drug user will make a suicide attempt. Both occasional and habitual use of cocaine can apparently increase suicide risks, while only habitual use of amphetamine and sedative-hypnotics is linked to increased risks. The researchers also concluded that occasional or habitual consumption of alcohol, marijuana\/cannabis or non-injection opioid drugs or medications does not substantially boost injection drug users\u2019 suicide risks. The study\u2019s authors especially emphasize the suicide-related dangers of cocaine and amphetamine consumption among people who use injection drugs. They believe that suicide prevention campaigns aimed at injection drug users should target individuals who take these or other stimulant substances. In addition, the authors point to a need for further research aimed at increased understanding of the reasons non-injection stimulant intake has such an effect on suicide rates among people who use injection drugs.