Table 3.1 divides the factors that influence drinking problems into three levels, namely the societal, the family/community, and individual. This framework is an oversimplification in a number of respects – most notably because the different factors interact across and within domains – but is useful as an analytic and descriptive convenience.
Availability of the drug
Drinking problems differ in an important respect from many other common health problems in that they can only occur in the presence of a particular environmental feature – namely, alcohol. One can experience chronic back pain, depression, or hypertension anywhere, but one can only have a drinking problem where there is alcohol. And, broadly speaking, the more readily available that alcohol, the more likely drinking problems are to occur, whether one is speaking of a society, a subculture, a community, or an individual.
The most fundamental ways in which societies determine alcohol availability are by laws regulating whether and under what conditions alcohol may be produced, sold, and consumed. Alcohol is de jure or de facto illegal in some regions (e.g., in parts of the Middle East), all of which have an unusually low prevalence of drinking problems. The United States’ experience of Prohibition has been represented in many movies and novels as actually having increased problem drinking, and this has become the fashionable view in many circles. However, in fact, the opposite occurred, with alcohol consumption and alcohol-related harm decreasing substantially despite inconsistent enforcement of the law (Hall, 2010). Similarly, the dearth of supply caused by a strike in Finland’s nationalized liquor industry led to reduced drinking problems (Mäkelä, 1980).
Societies that allow legal alcohol consumption typically set an age at which individuals are first allowed to purchase alcohol. As this age of purchase rises (e.g., from 18 to 21, as happened in the United States in the 1980s), alcohol consumption and alcohol-related harms decline among young adults.
Where alcohol is legal, it can be made less available through other policy actions, such as laws restricting sale to particular licensees and times of day. Variations in supply can and do influence demand, just as demand can stimulate greater supply. Policies that expand alcohol availability by reducing restrictions on its supply also tend to increase consumption. Manipulation of policy can therefore have enormous impact on the alcohol consumption of a population. Conversely, failure to utilize such controls can allow alcohol consumption to escalate and related problems to reach epidemic proportions (Alcohol and Public Policy Group, 2010; Anderson & Baumberg, 2006).
At a community level, factors such as the density and distribution of outlets may influence the local incidence of alcohol-related road traffic accidents or violence (Gruenewald & Treno, 2000). Furthermore, particular family and social networks are more or less “wet,” with some routinely providing alcohol at social, recreational, and community events and others not doing so.
Individuals also vary in the amount of alcohol available in their daily life context. A well-stocked bar in the home makes heavy drinking easier; living in the country 10 miles from the nearest pub makes it harder. Certain occupations also offer unusually high access to alcohol, including working in a restaurant, bar, or in the drinks industry itself.
Economic factors
In trying to explain why societies increase alcohol availability, it is informative to ask who benefits? Almost invariably, the answer is producers and sellers of alcoholic beverages.
The presence of a drinks industry, which can mass produce alcohol and then aggressively market and sell it, causes a wide-scale increase in alcohol consumption and drinking problems. A number of undeveloped societies that had only locally made, low-strength, hard-to-create alcoholic beverages (e.g., the Haya Indians who, through an elaborate process, made low-strength banana wine for ceremonial events [Carlson, 2006]), have seen a sharp rise in drinking problems with the arrival of stronger, attractively packaged, more easily acquired commercial alcoholic beverages such as the industry can provide.
The distribution of alcohol consumption is typically skewed in a population. For example, in the United States, the top 10 percent of drinkers account for the majority of national alcohol consumption (Cook, 2007). Alcohol producers and sellers are thus economically dependent on the existence of a large pool of problem drinkers: without those individuals who consume the equivalent of two or more bottles of wine a day, they would lose the bulk of their revenue. As a result of this economic reality, the industry tends to oppose any measure that would reduce the size of this heavy-drinking group.
From the same observation flows the recognition that increases in the effective price of alcohol are potent drivers of reduced alcohol problems because of their concentrated influence on the heaviest drinkers. For example, a 10 cent per unit tax might cost a typical drinkers a few dollars a year, but cost heavy drinkers $500 a year or more, thus providing a powerful incentive to reduce consumption.
Taxes are not the only effective way to use price to reduce problem drinking. Canadian provinces have adopted a minimum unit pricing policy that prevents the sale of the high-strength, low-cost beverages favoured by heavy consumers who contribute disproportionately to alcohol-related harm. Remarkably, from 2002 to 2009, a mere 10 percent increase in the average minimum price of alcoholic beverages predicted a 32 percent decrease in fully alcohol-attributed mortality (Zhao, Stockwell et al., 2013).
The United Kingdom has been considering minimum unit pricing, but the effort has thus far been successfully stopped by the drinks industry and its political allies in England and Wales. Scotland, in contrast, passed such a policy and was immediately sued in International Court by the Scotch Whisky Association and other wine and spirits producers, who claimed that minimum unit pricing violates European laws governing trade. The European Court of Justice produced a murky ruling in 2015 that left ambiguous whether Scotland can go forward with its policy, which would significantly reduce alcohol-related crime, hospital admissions, morbidity, and mortality.
Economic factors also shape drinking because different forms of alcohol are linked in the public mind (often through advertising) with different economic classes. A well-off person may therefore drink wine rather than beer, not out of genuine liking but based on a sense that wine is what well-off people drink. These class distinctions are often socially reinforced: the factory worker who goes to the pub with his friends after work and orders a glass of sherry may endure substantial derision.
Economic upheaval in a community can also stimulate problem drinking. Multiple studies have shown that economic shocks (e.g., the closing of a factory and associated mass redundancy in the community) tend to be followed by increases in family problems, psychiatric care-seeking, and disorder, all of which seem likely to have reciprocally positive relationships with problem drinking (Kiernan, Toro, Rappaport, Seidman, 1989). At an individual level, some would argue that the stress of being unable to pay bills and otherwise make ends meet drives people to drink; others would disagree and assert instead that, far from being victims of circumstance, problem drinkers bring such financial woes upon themselves. As usual, data have cast doubt on such one-sided explanations. Longitudinal research shows that although problem drinking does indeed generate economic strains for drinkers and their families, these strains in turn lead to a subsequent worsening of the drinking problem (Humphreys, Moos, & Finney, 1996).
In the wake of the popular book The Spirit Level, the idea that economic inequality caused drinking problems (indeed, virtually all human problems) enjoyed a lengthy European vogue. The evidence, however, is unkind to this proposition: indices of a society’s level of problem drinking either show no relationship or a positive relationship to economic inequality (Cameron, 2013).
Personal finances may shape the nature of drinking problems. Drink-driving arrests and boating accidents are more common among those who can afford such modes of transportation. Money may, to some extent, also allow a person to buy his or her way out of some drinking problems, at least in the short term; for example, by hiring a skilled barrister to have charges reduced or dismissed after an alcohol-involved mishap.
Values and norms
Across countries with similar legal regimes, the prevalence and amount of drinking varies substantially. Because drinking is often a social activity, and drinkers tend to make judgments about how much drinking is normal based on social comparisons, cultural norms of higher prevalence (i.e., few abstainers) and heavier volume drinking tend to reproduce themselves. This in turn leads to more drinking problems (Alcohol and Public Policy Group, 2010).
The quantity of alcohol consumed is not the only characteristic of drinking that affects the occurrence of drinking problems. Norms regarding patterns of alcohol consumption are also important. For example, different drinking problems are likely to arise in the woman who drinks four glasses of wine every day, as compared with the woman who drinks three bottles of wine in two days but who then drinks nothing for two or three weeks. Whereas the former is at greater risk of damage to the liver, brain, and other organs, the latter is at greater risk of marital disharmony and other social problems.
Cultural norms can influence the pattern of drinking just as much as the amount. In France, habitual consumption of wine with meals is associated with a relatively high but constant per capita consumption that predisposes toward chronic medical complications such as cirrhosis and certain cancers. In urban centres in the United Kingdom and North America, particularly among working-class men, alcohol is more likely to be consumed away from the home and often in relatively large quantities at a sitting. This pattern of drinking to intoxication is often accompanied by adverse consequences such as marital disharmony, accidents, interpersonal violence, and myocardial infarctions.
Both health professionals and the drinks industry attempt to influence alcohol consumption norms. Both have engaged in educational approaches, such as programmes informing young people of the risks of heavy alcohol consumption. In general, such programmes have a minimal impact, particularly in comparison to commercial marketing initiatives that portray drinking as glamorous, fun, and sexy. As a result, the drinks industry tends to endorse educational programmes, whereas health professionals are more keen on restricting pro-alcohol marketing, which seems more likely to reduce alcohol consumption (Alcohol and Public Policy Group, 2010).
Cultural norms may also influence the ways in which people behave when intoxicated. Drunken behaviour is shaped not only by the biological effects of alcohol as a drug, but also by social and cultural expectations as to how people will behave whilst intoxicated (MacAndrew & Edgerton, 1970). This may influence, for example, the likelihood of drunken antisocial behaviour.
One important element of culture is religious practice. Virtually all of the factors described thus far had some bearing on this (e.g., the Protestant religious groups who supported U.S. Prohibition, the Islamic prohibition on alcohol affecting anti-alcohol values in the Middle East). People with alcohol problems are far less likely to engage in religious practices than are the general population. In contrast, being raised in any mainstream religion is a potent protective factor against a young person developing an alcohol problem (Humphreys & Gifford, 2006).
Cultural norms around drinking often vary by gender, with drinking and heavy drinking much more tolerated in males than females in most of the world. However, along with many others changes in women’s social and economic status in Western countries has come changes in drinking norms. This has included a substantial increase in heavy drinking by women in developed nations and, with it, an increase in alcohol-related consequences for health and well-being. In light of the fact that the same amount of ethanol may affect women more profoundly than men, the old rule that any alcohol treatment programme will have a patient population that is two-thirds to three-quarters male may well be overturned.
Values and norms also are potent forces on drinking problems at the community level. For example, some neighbourhoods (usually but not always due to the presence of universities) are part of a youth culture in which drinking, dating, mating, and dancing are prevalent and intertwined. Communities also have drinking traditions, such as one can find on Newcastle’s Quayside or in the Irish ethnic bars of Boston’s Southie district, or, at the other extreme, the largely dry counties of parts of the U.S. Deep South.
Families, too, have their drinking traditions, which children observe and from which they learn. In some families, drinking heavily is a matter of pride and identity (e.g., “He could hold his drink like a real McAllister!”). Children raised by parents who personally provide them alcohol are particularly likely to engage in heavy drinking in their adolescence (Aiken et al., in press).
At an individual level, personal religious beliefs and values, as well as specific beliefs about alcohol, also may affect an individual’s likelihood of developing drinking problems. In general, these effects are intuitive (i.e., more religious beliefs and more anti-alcohol beliefs lessen drinking problems). But, for a small portion of people, these same beliefs may make drinking more exotic and hence an appealing forbidden fruit.
Biological factors
Biological factors that influence risk comprise two broad areas. The first is genetic/epigenetic and the second is neurological vulnerabilities of either nongenetic or unknown origins (some of which may someday be revealed as genetic/epigenetic). We discuss each factor in turn in this section.
Genetics
Many years of research into the genetics of alcohol use disorders identified no single causal “gene.” Rather, risk for disorder involves many possible genetic variants and their interactions with each other and the environment (Ducci & Goldman, 2008; NIAAA, 2013). For instance, genetic variation may contribute to differences in alcohol metabolism, reward/intoxication sensitivity, and withdrawal seizure potential as well as to the likelihood of developing dependence.
We now briefly describe which genes are involved in alcohol dependence and the various approaches used to study them. More comprehensive reviews are available (e.g., Hirschorn & Daly, 2005; NIAAA, 2013).
A gene is made of alleles, of which there can be different types or polymorphisms, thus resulting in heterogeneity. Common research approaches include genomics, which aims to identify genetic polymorphisms, and proteomics, which examines changes in function of the protein for which a gene codes (e.g., an enzyme or receptor). Much of recent research developments occurred due to technological advances and associated reduction in costs, as well as greater sample sizes and improved characterization of populations. As with neuroimaging, the aim of genetic studies is to improve understanding of the underlying neurobiology of alcohol use, misuse, and dependence as well as to identify novel targets for prevention and treatment.
Alcohol dependence, like many other disorders, tends to run in families. Studies have examined those families with monozygotic or dizygotic twins where at least one is affected by alcohol dependence. If the risk for alcohol dependence is associated with genetic factors, then monozygotic twins with identical genomes would have higher concordance than would dizygotic twins, who share only 50 percent of their genomes. Such an approach has indeed shown higher concordance in monozygotic twins, thus supporting a genetic influence to alcohol dependence. Through such twin studies and those involving adoption, the genetic component of the variance or heritability of alcohol dependence is estimated at around 50 percent (Enoch, 2013; Rietschel & Treutlein, 2013). Therefore, the interaction with environmental risk factors is equally as important.
To investigate which specific genes or areas of genome may underlie alcohol dependence, genetic markers have been compared in affected and nonaffected family members. In these family-based linkage studies, either a few markers or a genome-wide set of up to a few thousand markers are characterized or genotyped. The markers must segregate with the gene for the disorder. This approach has the advantage of being an unbiased, comprehensive search across the genome for markers. However, it depends on the size and number of families (generally needing hundreds) and the quality of the characterization of the individuals (phenotyping), as well as on the frequency and penetrance of the allele and links with markers. And findings may not generalize to other families or populations. Such an approach was undertaken in the Collaborative Study on the Genetics of Alcoholism.
An alternative research approach involves association studies in which genetic markers for a disease (e.g., alcohol dependence) or individual trait (e.g., impulsivity) are characterized across a population rather than within a family. Such a case-control approach involves comparing common allelic variants in cases (e.g., alcohol dependence) and controls and requires prior knowledge of the gene or area of genome of interest. This candidate gene approach is therefore simpler in design and cheaper to undertake, thus making it widely used. It has more power to detect the impact of a common genetic variant than do linkage studies.
Rather than a candidate gene approach, technological advances mean that the entire genome can now be interrogated using genome-wide association studies (GWAS) to identify genes or at least areas of the genome associated with disorders or traits (Hirschhorn & Daly, 2005; Rietschel & Treutlein, 2013). A variation may involve only a single DNA building block (i.e., nucleotide), and these variations are therefore known as single-nucleotide polymorphisms (SNPs). GWAS do not require an a priori hypothesis or knowledge about a particular gene or gene region, and they have been widely applied to understand the genetic contributions to many common complex disorders and behaviours. Several thousand individual subjects are required since most genetic variants have a modest effect on disease or contribution to a trait. In addition, given the large number of variants in the genome (up to 1 million), large samples are required for statistically appropriate analysis and interpretation. GWAS has led to a number of inconsistent findings and false positives, and thus any reported findings should be viewed with a healthy degree of scepticism until robustly replicated.
An alternative to identifying a single variant or gene is to study how genes work together in a network and/or interact with the environment. Such analysis will be necessary to characterize how individual genes and networks contribute to a complex disorder such as alcohol dependence. Due to the multiple comparisons involved, large datasets are required, with collaboration between centers or the use of publicly held databases (e.g., a connectome). One such approach, convergent functional genomics, integrates human and animal data to prioritize candidate genes to increase the ability to distinguish signal from noise even with limited size cohorts and datasets. In alcohol dependence, 10 genes were identified including for neurotransmitter receptors DRD2 and GABRA2 as well as SNCA, a presynaptic chaperone implicated in brain plasticity and neurogenesis, and GFAP, an astrocyte intermediate filament-type protein involved in neuron–astrocyte interactions, cell adhesion, and cell–cell communication (Levey et al., 2014).
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