Abstract

About 90% of people in Western countries use alcohol at some time in their lives, and 40% experience temporary or permanent alcohol-related impairment in some area of life as a result of drinking. Multiple sociocultural and environmental factors influence suicide rates, and thus studies conducted in one nation are not always applicable to other nations.

Impulsivity and aggression are strongly implicated in suicidal behaviour. Constructs related to aggression and impulsivity confer additional risk for suicidal behaviour in people with alcohol dependence. Lower serotonin activity is tied to increased aggression/impulsivity, which in turn may enhance the probability of suicidal behaviour.

Acute alcohol use is associated with suicide. Suicide completers have high rates of positive blood alcohol. Intoxicated people are more likely to attempt suicide using more lethal methods. Alcohol may be important in suicides among individuals with no previous psychiatric history.

Alcohol dependence is an important risk factor for suicidal behaviour. Mood disorder is a more powerful risk factor for suicide among problem drinkers as age increases. All individuals with alcohol use disorders should be assessed for suicide, especially at the end of a binge or in the very early phase of withdrawal. Middle-age and older men with alcohol dependence and mood disorders are at particularly high risk.

Alcohol consumption and suicide rates

About 90% of people in Western countries use alcohol at some time in their lives, and 40% experience temporary or permanent alcohol-related impairment in some area of life as a result of drinking.1 Alcohol use disorders are included in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) as alcohol abuse and dependence, and in the International Classification of Diseases (ICD-10) as harmful use and dependence on alcohol.2,3 This article emphasizes alcohol dependence more than alcohol abuse. Retrospective studies indicate that a large majority of suicide decedents with alcohol use disorders meet criteria for alcohol dependence.4–8 Alcohol dependence is a maladaptive pattern of alcohol use, leading to clinically significant impairment or distress, as manifested by three (or more) of the following, occurring at any time in the same 12-month period: (i) tolerance; (ii) withdrawal; (iii) the alcohol is often taken in larger amounts or over a longer period than was intended; (iv) there is a persistent desire or unsuccessful efforts to cut down or control alcohol use; (v) a great deal of time is spent in activities necessary to obtain alcohol, use alcohol, or recover from its effects; (vi) important social, occupational, or recreational activities are given up or reduced because of alcohol use; (vii) alcohol use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by alcohol.2

Prevalence of alcohol use disorders is higher for men. In the National Comorbidity Survey in the US, the 12-month and lifetime prevalences, respectively, of alcohol dependence were 10.7% and 20.1% for men and 3.7% and 8.2% for women in the general population.9

During recent years, the relationships between suicide rates and measures of alcohol consumption have been investigated in several studies.10–13 The association between alcohol consumption and suicide rates have been analysed in 13 nations of the world (Belgium, Canada, Czechoslovakia, Denmark, Finland, Luxembourg, the Netherlands, New Zealand, Norway, Sweden, Switzerland, the US, and West Germany);10 in 10/13, suicide rates were positively associated with per capita consumption of alcohol. In three nations (Denmark, Luxembourg, and New Zealand), this relationship was not found. Suicide rates have been associated with levels of alcohol consumption and heavy drinking in populations in the former USSR and Finland.12,14 However, the suicide rate in Hungary has shown a steady decline from 46 per 100 000 in 1984, to 32 per 100 000 in 1998, a fall of more than 30%.15 This has happened in spite of the fact that between 1989 and 1996 there was a 25% rise in official estimates of alcohol dependence rates and a six-fold increase in unemployment. Portugal has a fairly low suicide rate, and at the same time the Portuguese per capita alcohol consumption is among the highest in Europe.11 Moreover, the association between alcohol consumption and suicide over the regions of Portugal is negative. The inconsistent results of epidemiological studies of the relation between alcohol use and suicide indicate that multiple sociocultural and environmental factors influence suicide rates, and that studies conducted in one nation are not always applicable to other nations.16 It is of interest to note that, in a study of two countries with different alcohol use patterns, Norstrom17 found that alcohol consumption was more strongly related to suicide in Sweden than in France.

Effects of alcohol on impulsivity and suicidality

Impulsivity and aggression are strongly implicated in suicidal behaviour.18–22 Impulsivity has been related to suicidal and self-destructive behaviours within different psychiatric conditions, including alcohol and substance use disorders, mood disorders, conduct disorder, impulse control disorder, antisocial personality disorder, and borderline personality disorder. Studies have consistently demonstrated that constructs related to aggression and impulsivity confer additional risk for suicidal behaviour among persons with alcohol dependence and other substance misusers.22 In a study of detoxified subjects with alcohol dependence, more lifetime incidence of aggressive behaviour and higher scores on a trait measure of aggression/impulsivity distinguished those with a history of suicide attempts.20 Depressed subjects with a history of alcohol dependence have higher lifetime aggression and impulsivity, and are more likely to report a history of suicide attempts, childhood abuse, and tobacco smoking compared to depressed patients without alcohol dependence.23,24 The greater frequency of suicidal behaviour and severity of suicidal ideation in major depression with comorbid alcohol dependence appears to be related to associated aggressive traits.

Considerable evidence suggests an association between aggression and serotonin deficiency, and between aggression and alcohol consumption.21,25–27 Heavy drinking is associated with increased aggressive behaviour. For example, the number of days of heavy drinking by married or cohabiting alcohol-dependent men is a significant predictor of whether or not severe episodes of violence occur in these patients’ intimate relationships.27 Alcohol use also exerts substantial effects on serotonin metabolism.28–33 For example, post-mortem studies of brain tissue from patients with alcohol dependence revealed reduced serotonin transporter binding in the hippocampus.28,29 Similarly, binding was reduced in the 5-HT1A receptors of alcohol-consumers, compared to those of subjects who did not use alcohol.30 We found an anterior medial prefrontal cortical area where depressed patients with comorbid alcohol dependence had more severe hypofrontality than depressed patients without alcohol dependence.31 This group difference disappeared after fenfluramine administration, suggesting that serotonergic mechanisms play a role in the observed differences between the groups. Lower serotonin activity is tied to increased aggression/impulsivity, which in turn is presumed to enhance the probability of suicidal behaviour. For example, high-lethality depressed suicide attempters with comorbid alcohol dependence have lower cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA) levels, compared to low-lethality depressed suicide attempters with comorbid alcohol dependence.32

Acute alcohol use is associated with suicide.34–36 High (33–69%) rates of positive blood alcohol concentrations have been found among suicide completers.34,35 Alcohol intoxication increases suicide risk up to 90 times, in comparison with abstinence.34 A tendency of employed alcohol misusers to commit suicide during weekend has been partly explained by the direct effect of alcohol intoxication.37 There is evidence that alcohol intoxication predicts the use of more lethal means (e.g. a firearm) in the suicide.34,38 When intoxicated, people are more likely to attempt suicide using means that have a very low probability of survival.

It has been suggested that alcohol may play an important role in the events leading to suicide amongst individuals with no previous psychiatric history.39 The disinhibition produced by intoxication probably facilitates suicidal ideas and increases the likelihood of suicidal thoughts being put into action, often impulsively.

Alcohol dependence and suicide

Alcohol dependence is an important risk factor for suicidal behaviour.40–44 It has been suggested that lifetime mortality due to suicide in alcohol dependence is as high as 18%.40 However, Murphy and Wetzel41 reviewed the epidemiological literature and found that the lifetime risk of suicide among individuals with alcohol dependence treated in out-patient and in-patient settings was 2.2% and 3.4%, respectively. Nonetheless, individuals with alcohol dependence have a 60–120 times greater suicide risk than the non-psychiatrically-ill population.

A model of suicidal behaviour among subjects with alcohol dependence has recently been proposed.4 Predisposing factors that are presumed to increase (moderate) risk for suicide among individuals with alcohol dependence are aggression/impulsivity and alcoholism severity, which represent predominantly externalizing constructs, and negative affect and hopelessness, which represent predominantly internalizing constructs. Major depressive episodes and stressful life events—particularly interpersonal difficulties—are conceptualized as precipitating factors. Individuals with alcohol dependence who complete suicide are characterized by major depressive episodes, stressful life events, particularly interpersonal difficulties, poor social support, living alone, high aggression/impulsivity, negative affect, hopelessness, severe alcoholism, comorbid substance (especially cocaine) abuse, serious medical illness, suicidal communication, and prior suicidal behaviour.4,42 Partner-relationship disruptions are strongly associated with suicidal behaviour in individuals with alcohol dependence. There may be a broad-based social characteristic related to social stress that is associated with high rates of a variety of stress-related behaviours, including heavy alcohol use, divorce, and suicide.16

Being male and older than approximately 50 years of age increases the risk for completed suicide.42 For example, a recent study suggests that the risk for suicide associated with alcohol dependence increases with age.45 Mood disorder acts as a more powerful risk factor for suicide among problem drinkers as age increases.

There are several different possible relationships between alcohol dependence and suicide: alcohol use may affect suicidal ideation and behaviour; suicidal ideation may affect alcohol use; alcohol use and suicidal phenomena may affect each other; alcohol use may not itself affect suicide but may aggravate other factors that affect suicide; or alcohol use and suicidal behaviour may each be affected by some third factor without themselves being directly affected, e.g. alcohol dependence and suicide may be manifestations of the same underlying disorder.46 The relationship between alcohol use and suicide merits future research.

The combination of depression and alcohol dependence often leads to suicidal behaviour.4,41,47 Treatment for this fatal combination remains poor, and there is no evidence-based guidance as to the choice of biological and/or psychological treatments for this population when suicide is a prime concern. Future studies are necessary to determine what interventions may reduce suicidal behaviour in individuals with comorbid depression and alcohol dependence.

All individuals with alcohol use disorders should be assessed for suicide. Such assessments are especially important at the end of a binge or in the very early phase of withdrawal. Clinicians who encounter middle-age and older men with alcohol dependence and mood disorders should be alert to the high-risk status of these patients. Public education regarding the relation between alcohol consumption and suicide may also help reduce suicides among individuals with alcohol misuse.

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