Addiction and Suicide: An Unmet Public Health Crisis

Suicide is the tenth leading cause of death in the United States, with 44,193 suicides occurring each year, or 121 completed suicides per day. Approximately 494,169 individuals present to hospitals each year because of self-harm (1). Globally, it is estimated that about one million people die annually from suicide, equivalent to one death every 40 seconds. Suicide is a complex phenomenon caused by neurobiological, sociocultural, and genetic factors. This complexity is linked to risk factors such as chronic substance abuse, concomitant mental illness, personal stressors, family breakdown, previous suicide attempts, access to firearms, and history of lifetime physical or sexual abuse. These risk factors can interrelate with each other, be a product of each other, or operate independently.

There is a strong association between suicide and psychiatric disorders, and it has been estimated that up to 90% of people who commit suicide have one or more psychiatric comorbidities. Among these, affective disorders and posttraumatic stress disorder (PTSD) are associated with the strongest risk. Risk increases further among individuals who use alcohol. It is estimated that alcohol dependence alone carries a 7%-lifetime risk of suicide, compared with a 6% risk for affective disorders (2). Vulnerability is significantly increased and risk doubles with concomitant mental illness and substance use disorders, compared with affective disorders or alcohol misuse alone (3). Relative to the general population, individuals with substance use disorders are 10–14 times more likely to commit suicide (4).

Substance Use Disorders and Suicide

There is an established association between substance use disorders and suicide, but little is known about the underlying psychological mechanisms. The dysregulation of the neurotransmitter serotonin has been linked to depression, suicidal behavior, and substance abuse (5). Particularly, lower levels of 5-hydroxyindoleactic acid, a principal metabolite of serotonin, have been associated with increased suicide and suicidal behavior (6). Although researchers are examining many other potential neurobiological and genetic mechanisms of suicide, such discussion is beyond the focus of this article. Drug use increases the risk of suicidal behavior through both acute and chronic effects. Acutely, drug use distorts judgment, weakens impulse control, and interrupts neurotransmitter pathways (5). With longer periods of use, cognitive and behavioral control is impaired, subsequently leading to an increase in impulsive and aggressive behaviors. Physiological and metabolic stress resulting from use of substances can also lead to neurotoxic damage and severe medical consequences, especially among elderly individuals (7). Additionally, addiction induces negative emotional states, since it causes financial strain, social stigma, isolation, and difficulties at school.

Alcohol Use Disorder and Suicide

A recent national survey showed that 139.7 million individuals aged 12 and older consumed alcohol in the past month or longer, with 23% classified as binge drinkers and 6.2% as heavy drinkers (8). Lifetime prevalence of suicide attempts among individuals with alcohol use disorder is high, with heavy drinkers having a five-fold greater risk than social drinkers (9). About 40% of those seeking treatment for alcohol use disorder report at least one suicide attempt during their lifetime (10). Associations between alcohol use disorder and suicidality are further supported by an analytic review of retrospective and autopsy studies, which reported cases of completed suicide (10%–69%) and suicide attempts (10%–73%) that involved a positive toxicology screen for alcohol (11). Acute intoxication increases the risk for suicidal behavior through disinhibition, increased impulsivity, aggression, psychological distress, and impaired cognition (12). Chronic use may lead to neuroplastic brain changes, which may cause persistently negative mood states and deterioration of social relationships (13).

Although there are medications approved by the Food and Drug Administration for relapse prevention (disulfiram, acamprosate, and naltrexone), they are greatly underutilized, with only 3% of individuals with alcohol use disorder being prescribed any of these medications (14). Despite small-to-medium effect sizes, these medications have proven efficacy in improving relapse rates and have utility in reducing alcohol use disorder-related suicide risk.

Opioid Use Disorder and Suicide

The number of opioid prescriptions currently active in pharmacies equals our adult population. The correlation between opioid use and suicide has doubled in strength over the past decade. This is highlighted by a massive increase in overdose deaths, particularly those involving prescription opioids. Postmortem reports show that prescription painkillers are involved in 97.7% of opioid-related suicides (15). Despite a smaller percentage being attributed to opioid use, when involved, the risk of suicide increases 13.5 times (4). The literature supports that individuals with chronic pain are at higher risk for long-term opioid regimens, suicide, and development of psychiatric illnesses.

Individuals with histories of depression, PTSD, substance use disorders, and borderline personality disorder are more likely to be prescribed opioids for longer durations, which significantly increases the vulnerability of this population for unintentional opioid overdose deaths (16). The more lethal co-prescribing of opioids and benzodiazepine sedatives is also more common in these populations. One study found that after emergency department presentations for overdoses, subsequently filled prescriptions for opioids decreased by only 3.5%, while the rate of individuals engaging in postdischarge treatment increased by only 3.6% (17).

The crisis of opioid overdoses and deaths has been declared a public health crisis. Several approaches to address this crisis are underway. Emphasis is on public education, deployment of naloxone-overdose rescue kits, and improved access to medication-assisted treatment (methadone, buprenorphine, and naltrexone). Increased access to opioid agonist treatment is associated with a reduction in overdose deaths (18). The role buprenorphine plays in improving overall mood through the endogenous opioid system is well validated (19). Opioid users often receive medical attention in emergency departments, and this presents a golden opportunity to perform brief interventions, initiate medications, and facilitate outpatient treatment referral (20). An emergency department-initiated buprenorphine treatment regimen significantly increases engagement in long-term addiction treatment, decreases self-reported use of illicit substances, and decreases the burden on inpatient addiction treatment services (20).

Other Substances and Suicidal Behavior

Cocaine use has been linked to increased risk of suicide. This risk is higher if individuals who use cocaine are prescribed antidepressants, use alcohol, or have a history of childhood psychological abuse (21).

Tobacco use is one of the main preventable causes of death and contributes to an increased suicide risk proportional to the number of cigarettes smoked per day. Cessation has a positive impact, although former smokers will always carry a suicide risk higher than that of nonsmokers (22). There has been great reluctance on the part of physicians to treat tobacco use aggressively (e.g., with bupropion or varenicline), despite strong support for medication efficacy and patient motivation (23–25). In an effort to evaluate potential neuropsychiatric risks of varenicline, bupropion, and nicotine patches, the recent EAGLES [Evaluating Adverse Events in a Global Smoking Cessation Study] trial provided reassurance with regard to lack of moderate-to-severe neuropsychiatric adverse events, even in psychiatrically ill populations (26).

Risk Assessment and Management

A suicide assessment identifies static (unchangeable) and dynamic (modifiable or treatable) risk and protective factors that facilitate diagnosis, treatment, and safety management. To our knowledge, no single assessment method has been tested for reliability and validity; thus, emphasis should be placed on identifying and modifying dynamic risks (Table 1) (27, 28).

Common modifiable risk factors are medical illness, psychiatric symptoms, active substance abuse, current life crises, unemployment, lack of social support, and access to firearms. Static risk factors help stratify the level of risk but are typically of little use in treatment. A provider should competently review dynamic and static factors for risk assessment before establishing a comprehensive management plan that includes an accurate diagnosis (29). Dual diagnoses are often overlooked but should be identified due to an association with poor prognosis. Patients with dual diagnoses are at greater risk for a suicide attempt than those with a single diagnosis. Therefore, a comprehensive plan of preventive interventions and appropriate screening for substance use should be performed to confirm dual-diagnoses status.

In facilitating diagnosis, screening is the mainstay in today's preventive health care practices, allowing for early identification of those at risk for developing substance use disorders. Research has demonstrated that screening and brief intervention can promote significant reductions in alcohol and tobacco use. Screening not only assesses whether an individual has substance use disorder but also whether he or she is engaging in risky patterns of use. Early screening tools for alcohol use disorder, such as the Michigan Alcoholism Screening Test and the CAGE [cut-annoyed-guilty-eye] Questionnaire, were developed to detect alcohol dependence. Over time, instruments, such as the Alcohol Use Disorders Identification Test, were introduced to assist with identification of risky and hazardous use.

Conclusions

Comorbid substance use increases the risk of suicide, especially in clinical populations already at increased risk. As clinicians, we should implement screening tools to better identify individuals at greater risk. Additionally, we should implement pharmacotherapies with evidence for efficacy in addressing substance use and provide quality relapse-prevention strategies for our patients. All individuals who abuse substances should receive a thorough suicide risk assessment in order to determine the level of care that is needed.

Key Points/Clinical Pearls