Complex and Interacting Factors Predispose People to Addiction

Complex and interacting factors can predispose people to developing addiction, defined by the National Institute on Drug Abuse as “a chronic, relapsing brain disease that is characterized by compulsive drug seeking and use, despite harmful consequences.” Genetics, psychology, psychiatry, and sociology are contributing to a more complicated understanding of how and why addiction develops in 1 in 7 people, or about 14%.

Detail of collage, Mary Wilson Burnette Giles, 1963

Genetics and Epigenetics

Genetics is well-known as the field that studies DNA, or the amino acid code that serves as a blueprint for living creatures. Epigenetics, being a newer sub-field of genetics, is rather less well-known. Epigenetics is a field examining the chemical compounds and proteins that attach to DNA, and influence how and whether the DNA is translated. For example, certain proteins can turn genes on or off, or modify how much protein is made from (i.e. translated from) a gene. Epigenetic changes often happen due to environmental influences throughout a person’s life, and are heritable.

An estimated 40-60% of addiction risk is genetic, but researchers don’t know yet which specific genes are at the root of the risk. This is in part because, in the case of addiction, each suspected gene has a very small influence, but all the genes together seem to have a very large influence. To identify all of the small influences of the individual genes would require experiments with very large sample sizes.

The question of which genetic factors predispose people to developing addiction is further complicated by epigenetics, such that a person’s risk may be increased or decreased depending on his or her environment. The drug itself, social interaction, or stressful life events can all alter a person’s epigenetics so that the person is at higher risk for addiction. Because of these interactions between genetics and environment, so far it is impossible to say exactly how much of addiction is due to nature (genetics/inherited epigenetics) and how much to nurture (environment/experiences). It is safe to say that people are or become predisposed to developing addiction, probably due to both genetic and epigenetic variables.

Mental Illnesses and Personality Disorders

People with addiction can have co-occurring mental illnesses and personality disorders, for which they may have been self-medicating when they developed addiction. Some of the genetic risk for addiction may be indirect, via a genetic risk for other disorders.

“In fact, the majority of genetic influence on substance use outcomes appears to be through a general predisposition that broadly influences a variety of externalizing disorders and is likely related to behavioral undercontrol and impulsivity, which is a heterogeneous construct in itself.”
Dick 2016

One study found that 28% of people with alcohol use disorders (AUDs) and 47.7% of people with drug use disorders had at least one personality disorder. Specifically, 18% of people with substance use disorders (SUDs) overall (including AUDs) have antisocial personality disorder, a rate more than four times that of the general population, which may be the source of the myth of the “addictive personality.”

Disorders that are commonly comorbid with addiction include:

  • Anxiety and mood disorders
  • Schizophrenia
  • Bipolar disorder
  • Major depressive disorder
  • Conduct disorders
  • Post-traumatic stress disorder (PTSD)
  • Attention deficit hyperactivity disorder
  • Antisocial personality disorder

When these disorders precede the development of addiction, they are said to be precursors, and may contribute to overall addiction risk. We cannot say yet, however, whether any of these precursors have definitive, causal influence in the development of addiction.

Trauma

PTSD is one of the disorders most commonly comorbid with addiction, and warrants special emphasis. The relationship between trauma and addiction is very strong, and trauma is suspected to be a causal influence in the development of addiction. An estimated 66% of people with SUDs have experienced trauma, and about half have PTSD.

Trauma may include emotional, sexual, or physical abuse, and is especially damaging for children. Adverse childhood experiences (ACEs) are known to increase addiction risk, with children who have experienced 5 or more ACEs 7 to 10 times more likely to develop addiction. Even one ACE before the age of 15 doubles a child’s risk of addiction, based on a study of the population of Sweden. People who develop PTSD or experience trauma symptoms following community violence are also known to be at elevated risk for developing addiction.

Personality and Temperament

While there is no one addictive personality, certain personality and temperament traits are associated with higher rates of addiction.

“Yes, some stand out because they are antisocial and callous – but others stand out because they are overly moralistic and sensitive. While those who are the most impulsive and eager to try new things are at highest risk, the odds of addiction are also elevated in those who are compulsive and fear novelty. It is extremes of personality and temperament – some of which are associated with talents, not deficits – that elevates risk. Giftedness and high IQ, for instance, are linked with higher rates of illegal drug use than having average intelligence.”
Maia Szalavitz

Some of these personality traits may be or become severe enough to be diagnosable as a personality disorder, but in other cases a person may simply be prone to feeling anxious or hopeless, or being impulsive or sensation-seeking. These traits would also be accurately described as being precursors to addiction, possibly increasing addiction risk.

Attachment Security

Attachment theory has been studied for decades, beginning with research on infant-parent relationships, and expanding to research on adult relationships.

Attachment theory examines the quality of infant relationships with their caregivers, and correlates these relationships with the quality of relationships people have later in life. Basically, the more securely an infant bonds with a caregiver, the more secure that infant will feel in other relationships later in life.”
– Addiction Recovery with Others is Easier than Recovery Alone

Some theorize that addiction is an attachment disorder. Dr. Philip Flores is the founder of this idea, arguing that people with poor attachment are suffering from emotion regulation difficulties, and are essentially unable to regulate their self-esteem and relationships without healthy attachment. He posits that people suffering from insecure attachment use substance or behaviors to substitute for healthy relationships, which seem at first to help but ultimately exacerbate their problems.

We do not know whether Dr. Flores is correct, but we do know that insecure attachment styles are associated with addiction and with poor emotion regulation, as well as with other mental illnesses. Insecure attachment may therefore be considered to be another precursor to the development of addiction, in close association with the risk factors of co-occurring mental disorders.

Recently, researchers are exploring whether oxytocin (the neuropeptide and hormone thought to be responsible for social bonding) and social attachment may protect against addiction and stress. The neurological systems for stress coping and for social attachment overlap, and these researchers hypothesize that oxytocin is responsible for the transition people experience from wanting/searching for social attachment to liking/loving a person.

“The authors suggest that through dopaminergic, serotonergic and endogenous opioid mechanisms, oxytocin is involved in shifting the balance between wanting and liking in corticostriatal loops by facilitating consolidation of social information from ventral reactive reward systems to dorsal internal working models that aid in prospectively selecting optimal actions in the future, increasing resilience in the face of stress and addiction.”
Tops et al., 2014

Essentially, Tops et al. suspect that the process of developing familiarity and liking for other people, with the help of oxytocin, helps people to cope with stress, and makes them more resilient and less likely to become addicted.

Socioeconomic Influences

Poverty is a source of chronic stress, which may increase a person’s risk for mental illnesses. Fatal opioid overdose rates and emergency room visits are strongly correlated with unemployment rates, increasing 3.6% and 7% respectively for each 1% increase in unemployment. People in poverty are more likely to become addicted, in part because people in poverty are more likely overall to develop mental illnesses. Furthermore, mental illnesses may make it harder for a person to gain or keep employment and/or housing, which could lead to further or worsening poverty.

“Growing international evidence shows that mental ill health and poverty interact in a negative cycle in low-income and middle-income countries.”
Lund et al., 2011

Poverty is also known to have intergenerational influences, with chronic stress and poverty having epigenetic (therefore heritable) impacts on, for example, a person’s ability to cope with stress.

Other social-environmental influences may put someone at increased risk for addiction. For example, being surrounded by many people who use drugs tends to increase a person’s risk of developing an SUD, because the drugs are more available and people are more likely to use together more often. Furthermore, drug use in the home may result in more stressful situations, including poverty, that in turn put other people in the home at higher risk for addiction or other mental illnesses. Especially in cases of social isolation and poverty, such as in some rural areas of America, almost everyone in a community may develop addiction (e.g., the recent opioid epidemic).

Physiological Influences

Some people metabolize alcohol differently than others, and so are at higher risk for addiction. Some people are at heightened risk because of sleep disturbances or poor sleep quality. Others are at risk because of physical pain. People with physical disabilities, and/or traumatic brain injuries, are also known to be at higher risk for addiction. Women and men are equally likely to develop addiction, but sex, gender, race and ethnicity may influence the course addiction takes.

Developmental Stage

Adolescents are at higher risk for developing addiction, though many end up “aging out,” and recover on their own once their brains have developed. Human development is highly influenced by social environment, as well as genetics. If many of the above risk factors coincide with adolescence, a person is more likely to develop addiction.

Because of extreme variability in the precursors and predisposing conditions influencing the development of addiction, we may never have a one-size-fits-all treatment solution. By understanding all of the complex and interacting variables that predispose people to addiction, however, we can begin to determine which people are at highest risk, identify risks that we can mitigate, and create individualized treatment plans to ameliorate addiction, co-occurring mental and physical disorders, and life stressors.

Photo: Detail of collage, Mary Wilson Burnette Giles, 1963

This post was last updated 5/4/17.

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