Nature vs. nurture: How genetics and environmental factors play a role in addiction
Though genetics play a role in addiction, they do not alone determine whether or not a person will abuse a substance, according to Slippery Rock University assistant professor and counselor Natalie Drozda.
The central debate at the heart of biological study is “nature vs. nurture” — how much of human behavior is dictated by genetics and how much is dictated by environmental factors. This applies to all facets of human behavior, and susceptibility to addiction is no exception.
“Genes are not destiny,” Drozda said. “While some individuals may be more susceptible to developing addictions due to a genetic predisposition, environmental factors contribute to a person’s behavior just as much if not more than genes.
“Individuals with similar genetic profiles but drastically disparate social supports and attachment styles will fare differently under stress.”
Just as certain families have a genetic history of cancer or heart disease, others have a genetic history with addiction, she said.
But while genetics have a part to play, she suggests the environment as a potentially stronger factor in determining whether or not someone struggles with addiction.
It is theoretically possible for someone to develop a substance abuse disorder even if neither of their parents did so. Conversely, it is also possible for a child to avoid substance abuse even if both of their parents failed to do so.
A study led by Dr. Howard J. Edenburg of Indiana University in 2013 identified several genes with strong links to impacting alcoholism, including ADH1B and ALDH2.
ADH1B helps to catalyze the oxidation of alcohol to acetaldehyde, while ALDH2 encodes the mitochondrial aldehyde dehydrogenase (ALDH) enzyme, which is the principal catalyst for oxidation of acetaldehyde during alcohol metabolism, the study shows.
It also noted that other genes affect the risk of alcoholism or related traits, too, including GABRA2, CHRM2, KCNJ6 and AUTS2.
“As more variants are analyzed and studies are combined for meta-analysis to achieve increased sample sizes, an improved picture of the many genes and pathways that affect the risk of alcoholism will be possible,” the study states.
A scientific review, conducted by Joseph Deak and Emma Johnson in 2021, concluded that genetics had roughly a 50% influence on addiction. Thus, a family history of alcohol abuse would increase the likelihood by 50% of falling into alcohol abuse themselves.
The review referred to substance use disorders as “heritable psychiatric disorders that are influenced by both environmental and genetic factors.”
The key link between genetics and addiction is a little neurotransmitter called dopamine, which is considered the “reward center” of the central nervous system and allows humans to feel pleasure and motivation, Donna Lamison, executive director of NAMI Butler County, explained.
Illicit substances create floods of dopamine and a surge of euphoria, teaching the brain to experience the feeling again and again despite the ill effects, she said.
“The substances people abuse target the brain’s reward system, a network reliant on dopamine for communication,” said Lamison. “Genetic and environmental elements intricately shape the operation of this system.”
She went on to say that genetic and environmental elements come together to affect a person.
“Although certain individuals might possess a genetic disposition toward addiction vulnerability, the influence of a nurturing environment can deter this predisposition from manifesting, potentially averting addiction,” Lamison said. “Conversely, the scenario can unfold in reverse: genetic susceptibility coupled with adverse environmental factors might amplify the risk of addiction.
“In essence, while genetics does exert influence, it doesn’t solely dictate the course of events.”
There are also studies to suggest that environmental factors play an equal, if not greater role, in driving individuals toward substance abuse. For example, one 2016 study in the International Journal of Environmental Research and Public Health identified several risk factors which could lead someone down the wrong path.
These include easy access to illicit substances, economic disadvantage, and inability to access treatment.
“When nurturing from caregivers and healthy relational templates were lacking during critical development periods in formative years, sometimes individuals develop relationships with substances later in life to fill a void,” Drozda said.
According to Bette Peoples, executive director of the Grapevine Center in Butler, environmental factors can work the other way around, too. While a negative environment prompts a negative response, a positive environment can yield positive change.
A nurturing environment can also prevent people struggling with addiction from relapsing while they are actively trying to recover, Peoples said.
“If somebody is trying to get out of something and they smell marijuana, that’ll trigger it or if they go to a bar,” said Peoples. “Lots of things, I think, could trigger (a relapse).
