Some people are fairly susceptible to the effects of alcohol and experience them even when they drink small amounts. Conversely, others have a relative lack of alcohol susceptibility and can drink fairly large amounts before they experience any appreciable effects. In a report published in June 2014 in NIAAA Spectrum, the National Institute on Alcohol Abuse and Alcoholism explains the dangers associated with having a high alcohol threshold. Chief among these dangers is an increased chance of developing diagnosable symptoms of alcohol abuse and/or alcoholism (both included as indications of a condition called alcohol use disorder).
Alcohol produces its basic intoxicating effects by accessing nerve cells inside the central nervous system (brain and spinal cord) and altering their normal rate of activity and communication. Broadly speaking, the specific effects of intoxication vary with the amount of alcohol consumed. Public health officials and law enforcement officials commonly use a measurement of the amount of alcohol contained in any given volume of blood, blood alcohol concentration or BAC, to help track the most common mental and physical symptoms of drunkenness. At the level established for legal intoxication (a BAC of 0.08 percent), the average person has clearly lost some physical and mental competence. Blood alcohol concentrations below 0.08 percent typically produce less noticeable functional changes, while concentrations above this percentage typically produce more glaring functional changes.
Even when they consume similar or identical amounts of alcohol, not all people subjectively feel equally drunk. A substantial portion of the variation in alcohol susceptibility comes from genetically inherited tendencies passed down through family bloodlines. Some of the susceptibility to intoxication also has a gender basis. As a rule, factors such as smaller body size and a relatively slow rate of alcohol processing mean that women get drunker than men when they consume alcohol in equal amounts. Other noted influences on susceptibility to the intoxicating effects of alcohol include how frequently you drink, how much alcohol you typically consume, general state of physical and mental wellbeing, age at first use of alcohol, any history of alcohol exposure in the womb, the length of time over which you have regularly consumed alcohol and current age.
The American Psychiatric Association established alcohol use disorder as a diagnosis in 2013. This diagnosis treats non-addicted alcohol abuse and alcoholism as intertwined, potentially co-occurring problems rather than as separate health concerns. Such a viewpoint reflects a firm consensus among doctors and the research community that the symptoms of alcohol abuse and alcoholism often overlap or appear in forms that are essentially indistinguishable. There are three degrees of alcohol use disorder – mild, moderate and severe – defined by the number of symptoms present in an affected person. Minimally impacted people have two or three symptoms of serious alcohol problems, while maximally impacted people have 11 symptoms.
People who can drink a fairly large amount of alcohol before feeling intoxicated sometimes believe that they have reduced risks for serious alcohol-related harm. However, the reverse appears to be true. In a series of studies reviewed by the National Institute on Alcohol Abuse and Alcoholism, several teams of researchers conducted experiments designed to uncover biological factors that alter sensitivity to the effects of alcohol, as well as experiments designed to uncover any connections between intoxication susceptibility and the chances of developing alcohol use disorder.
The research teams explored responses to alcohol intake objectively by using controlled laboratory conditions to explore the connection between blood alcohol levels and symptoms of intoxication such as speaking difficulties, impaired muscle control and loss of consciousness. They also explored responses to alcohol intake more subjectively by asking study participants to describe how much alcohol they needed in order to feel drunk. After gathering this information, the researchers tracked the participants over a number of years and identified those individuals who developed diagnosable cases of alcohol abuse/alcoholism. After analyzing their completed work, the researchers concluded that people with a high drinking threshold tend to do two things more often than their counterparts with a lower drinking threshold: consume more alcohol over time and develop cases of alcohol use disorder as they get older.
The NIAAA notes that a genetically conferred lack of alcohol sensitivity may be fundamentally distinct from the rising tolerance to alcohol intake found in people who habitually drink large amounts. The agency also notes that public health officials may be able to use awareness of high drinking thresholds to develop appropriate preventive interventions for affected individuals.