The development of an addiction, or substance use disorder, never occurs as a result of a single cause. Substance use disorders are very complicated disorders that develop under a number of different contexts and in many different individuals. There are no guarantees that one will or will not develop a substance use disorder unless one is never exposed to a potential addicting substance. However, since many different types of substances (drugs, alcohol, etc.) and behavioral experiences can be associated with addictive-type behaviors, nearly everyone has some level of risk to develop some type of substance use disorder or addictive behavior even though the majority of individuals will not develop these behaviors.
A risk factor represents a particular condition or situation that increases the probability that one will develop a specific disorder or disease. Conversely, the presence of certain protective factors decreases the probability that one will develop a specific disorder or condition. Some risk factors have significantly higher probabilities associated with their presence than others, and an individual who has multiple risk factors will be at higher risk to develop whatever disorder or condition the risk factors are associated with. However, there is no identified risk factor that is definitively associated with the development of addictive behaviors. Instead, the presence of certain risk factors increases the chances that one might develop an addictive behavior.
According to the American Psychiatric Association, the American Society of Addiction Medicine, and the World Health Organization, the most salient risk factors associated with the development of substance use disorders and other addictive behaviors follow:
Genetic factors: A great deal of research investigating the association between certain genetic factors and the development of addictions has indicated that one’s genes play an important role in increasing or decreasing the probability that an individual will develop an addictive behavior. There are a number of different research methods that look at the association between certain genetic factors and the increased risk to develop addictive behaviors. Some of the most common associations that have been used to support the notion that genetic factors significantly contribute to the development of addiction are:
- Family studies: Research has long indicated that addictive behaviors are more common in some families than others. Having a first-degree relative with a substance use disorder or other addiction increases the probability that one will develop some type of addictive behavior. Even having other relatives, such as uncles, aunts, grandparents, etc., with addictive behaviors is also associated with an increase in the probability that one may develop a substance use disorder or other addictive behavior. The stronger the relationship to the relative with the addictive behavior, the higher the risk is that one will develop a substance use disorder or other addictive behavior; however, this relationship is far from definitive or even clearly defined. Moreover, having a first-degree relative with a substance use disorder or other addictive behavior is also evidence that addictions and substance use disorders may be learned.
- Twin studies: Some of the strongest evidence for a genetic association for the development of addictions comes from twin studies, particularly identical twins (who are genetically 100 percent alike) that were adopted by different families and reared apart. There are a number of these studies. In general, research findings indicate that if one of these twins has a substance use disorder, the other twin is far more likely to develop a substance use disorder than fraternal twins or other siblings. This suggests that there is a strong genetic component to the development of addiction.
- Genetic association studies and heritability: A number of studies focus on statistical associations between certain genes. These studies examine individuals who have these genes and their probability of expressing addictive behaviors. There are multiple genes associated with increased probabilities of developing addictions. In addition, a statistical technique known as heritability, which attempts to estimate the proportion of the differences in behaviors or traits between different individuals that can be assigned to genetic differences, indicates that individuals who express addictive behaviors have significant genetic associations to these behaviors. However, the heritability statistic has a number of flaws.
While it is certain that genetic influences do increase the probability that someone will develop an addictive behavior, they do not ensure that anyone will definitely develop an addiction. Moreover, there is no evidence that certain genetic factors cause anyone to develop an addiction.
- Gender: Males are slightly more likely to develop substance use disorders than females, although this trend is weakening.
- A co-existing mental health disorder: A significant risk factor for the development of any type of addictive behavior is having a diagnosis of some other mental health disorder, such as depression, an anxiety disorder, etc. Certain classes of mental health disorders, such as depressive disorders and anxiety disorders, are associated with a greater potential for co-occurring substance use disorders than others; however, the bottom line is that anyone who has any type of mental illness is at a greater risk for the development of addictive behavior.
- Lack of social support: Individuals who perceive that they lack social support are at greater risk for the development of substance use disorders and addictive behaviors. It is important to note that the key term here is that they perceive they lack social support. Social support can come from family members, peers, and other sources, and often individuals who may actually have relatively substantial social support may not perceive that this support network exists.
- Peer group: An individual’s peer group is particularly influential on their behavior. This influence is stronger for younger individuals; however, it affects people of all ages.
- Subclinical expressions of depression, loneliness, and anxiety: As indicated above, individuals with formal mental health diagnoses of specific disorders are at greater risk to develop addictive behaviors. However, even sub clinical manifestations of depression or anxiety that do not meet the formal diagnostic criteria for a mental health disorder can increase the risk for the development of addictive behaviors.
- Using certain types of drugs: Certain types of drugs have higher potentials for the development of addictive behaviors and substance use disorders than others. For example, individuals using highly addictive drugs with a high potential for the development of physical dependence, such as heroin and methamphetamine, are far more likely to develop formal substance use disorders than individuals who use drugs with less potential for the development of formal substance use disorders, such as hallucinogens (e.g., LSD or magic mushrooms).
- Drug availability: People who live in conditions where drugs or alcohol are readily available are more likely to develop substance use disorders than individuals who have difficulty procuring these substances.
- Trauma and stress: Individuals who experience extreme trauma or extreme stress are more likely to develop substance use disorders than individuals who do not have these experiences. However, there is no guarantee that experiencing extreme trauma, such as sexual abuse as a child, will result in the development of a substance use disorder or other addictive behavior.
- Other negative experiences: A number of other negative experiences have been identified as risk factors for the development of substance use disorders, including having extreme financial difficulties, growing up in poverty, experiencing a significant loss, etc.
It is important to reiterate that having any or all of the above experiences offers no guarantee that anyone will develop any type of substance use disorder or addictive behavior. These factors are merely associated with an increased risk to develop addictive behaviors; however, there also a number of protective factors that offset these often very salient risk factors. For example, the relationship between heredity (genes) and the development of a substance use disorder is relatively strong but not perfect. This suggests that even in the presence of significant salient genetic risk factors, a number of individuals must also have experienced other protective factors that offset their genetic risk. Not every individual who develops a severe major depressive disorder also develops a co-occurring substance use disorder. This indicates that other factors must be involved in the development of addictive behaviors in addition to clinical depression.
Protective factors that are important include:
- Strong perceived social support
- Positive experiences that foster the perception of competence
- Good social skills and problem-solving skills
- A strong sense of community