Binge drinking is a growing public health crisis − a neurobiologist explains how research on alcohol use disorder has shifted

Signaling molecules in the prefrontal cortex are altered by repeated exposure to excessive alcohol consumption in animal models. jambojam/iStock via Getty Images^[15]

The biology of addiction

While problematic alcohol consumption has likely occurred as long as alcohol has existed, it wasn’t until 2011 that the American Society of Addiction Medicine recognized substance addiction as a brain disorder^[16] – the same year as Winehouse’s death. A diagnosis of an alcohol use disorder is now used over outdated terms such as labeling an individual as an alcoholic or having alcoholism.

Researchers and clinicians have made great strides^[17] in understanding how and why drugs – including alcohol, a drug – alter the brain. Often, people consume a drug like alcohol because of the rewarding and positive feelings it creates, such as enjoying drinks with friends or celebrating a milestone with a loved one. But what starts off as manageable consumption of alcohol can quickly devolve into cycles of excessive alcohol consumption followed by drug withdrawal.

While all forms of alcohol consumption^[18] come with health risks, binge drinking appears to be particularly dangerous^[19] due to how repeated cycling between a high state and a withdrawal state affect the brain. For example, for some people, alcohol use can lead to “hangxiety^[20],” the feeling of anxiety that can accompany a hangover.

Repeated episodes of drinking and drunkenness, coupled with withdrawal, can spiral, leading to relapse and reuse of alcohol. In other words, alcohol use shifts from being rewarding to just trying to prevent feeling bad.

It makes sense. With repeated alcohol use over time, the areas of the brain engaged by alcohol can shift away from those traditionally associated with drug use and reward or pleasure to brain regions more typically engaged during stress and anxiety^[21].

All of these stages of drinking, from the enjoyment of alcohol to withdrawal to the cycles of craving, continuously alter the brain and its communication pathways^[22]. Alcohol can affect several dozen neurotransmitters and receptors^[23], making understanding its mechanism of action in the brain complicated.

Work in my lab focuses on understanding how alcohol consumption changes the way neurons within the prefrontal cortex communicate with each other. Neurons are the brain’s key communicator, sending both electrical and chemical signals within the brain and to the rest of your body.

What we’ve found in animal models of binge drinking is that certain subtypes of neurons lose the ability to talk to each other appropriately. In some cases, binge drinking can permanently remodel the brain. Even after a prolonged period of abstinence, conversations between the neurons don’t return to normal^[24].

These changes in the brain can appear even before there are noticeable changes in behavior^[25]. This could mean that the neurobiological underpinnings of addiction may take root well before an individual or their loved ones suspect a problem with alcohol.

Researchers like us don’t yet fully understand why some people may be more susceptible to this shift, but it likely has to do with genetic and biological factors, as well as the patterns and circumstances under which alcohol is consumed.

Work in the author’s lab explores how alcohol use can alter the way neurons communicate in the prefrontal cortex brain region. Estrogen receptors are labeled in purple and receptors for somatostatin, a key regulatory hormone, in blue. Victora Nudell

Women are forgotten

While researchers are increasingly understanding the medley of biological factors that underlie addiction, there’s one population that’s been largely overlooked until now: women.

Women may be more likely than men to have some of the most catastrophic health effects caused by alcohol use, such as liver issues, cardiovascular disease and cancer^[26]. Middle-aged women are now at the highest risk for binge drinking^[27] compared with other populations.

When women consume even moderate levels of alcohol, their risk for various cancers goes up, including digestive, breast and pancreatic cancer^[28], among other health problems – and even death. So the worsening rates of alcohol use disorder in women^[29] prompt the need for a greater focus on women in the research and the search for treatments.

Yet, women have long been underrepresented in biomedical research.

It wasn’t until 1993 that clinical research funded by the National Institutes of Health was required to include women as research subjects. In fact, the NIH did not even require sex as a biological variable to be considered^[30] by federally funded researchers until 2016. When women are excluded from biomedical research, it leaves doctors and researchers with an incomplete understanding of health and disease, including alcohol addiction.

There is also increasing evidence that addictive substances can interact with cycling sex hormones^[31] such as estrogen and progesterone^[32]. For instance, research has shown that when estrogen levels are high, like before ovulation, alcohol might feel more rewarding^[33], which could drive higher levels of binge drinking. Currently, researchers don’t know the full extent of the interaction between these natural biological rhythms or other unique biological factors involved in women’s health and propensity for alcohol addiction.

Middle-aged women are at the highest risk for some of the most severe health consequences of binge drinking. Peter Dazeley/The Image Bank via Getty Images^[34]

Looking ahead

Researchers and lawmakers are recognizing the vital need for increased research on women’s health. Major federal investments^[35] into women’s health research^[36] are a vital step toward developing better prevention and treatment options for women.

While women like Amy Winehouse may have been forced to struggle both privately and publicly with substance use disorders and alcohol, the increasing focus of research on addiction to alcohol and other substances as a brain disorder will open new treatment avenues for those suffering from the consequences.

For more information on alcohol use disorder, causes, prevention and treatments, visit the National Institute on Alcohol Abuse and Alcoholism^[37].

Authors: Nikki Crowley, Assistant Professor of Biology, Biomedical Engineering and Pharmacology, Penn State

Read more https://theconversation.com/binge-drinking-is-a-growing-public-health-crisis-a-neurobiologist-explains-how-research-on-alcohol-use-disorder-has-shifted-227313

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