What role do genetics play in addictions, especially alcoholism?
A summary of research over the past 35 years shows that for alcoholism, by far the most studied addiction, there is no genetic factor for most people. There is a subset of people who may have increased genetic risk but we now know conclusively that there is no single gene for alcoholism. Indeed, given what genes do (code for amino acid chains of protein molecules) it would be impossible for there to be a gene for a behavior as complex as addiction. The fact that there is any genetic factor at all means that there may be many, perhaps hundreds, of genes that could bear on the condition. Inheritance of alcoholism is similar to other conditions like high blood pressure where there is no specific gene or set of genes for it but a combination of many factors including some genetic predisposition for some people with many non-genetic factors such as behavior, personality, and environment. Given our knowledge of the psychological basis for addiction, it is possible that genetic factors that might influence tolerance of frustration could have some role for some people. For a full discussion of the role of genetics in addiction, see chapter seven of "The Heart of Addiction".
How about the role of physical addiction? I've heard that addiction is a physical disease caused by being addicted to drugs.
Physical addiction is often confused with the problem of addiction in general. Actually, it plays a very minor role. Physical addiction is important mainly as a medical problem when people try to withdraw from certain drugs. Sudden withdrawal from drugs like alcohol or certain tranquilizers (benzodiazepines like Valium or Xanax) can be life-threatening. But in terms of why people perform addictive behavior, physical addiction is not important. For one thing, physical addiction is easy to treat. People can be safely detoxified (withdrawn) from drugs usually in a matter of days. But as we all know, even months or years later they may return to addictive use of the same substances. In one famous study, even physical addiction to heroin was shown to be unimportant in leading people to use it addictively. Many soldiers returning from Vietnam were physically addicted to heroin, yet after they came home and were withdrawn from the drug over 90% of them stopped using it. Meanwhile, stateside heroin addicts could not stop using the drug by just medically withdrawing them. This study showed that even for a drug as famously "addictive" as heroin, merely being physically addicted couldn't turn somebody into an "addict". What is important is not becoming physically addicted, but the drive that leads people to keep using the drug even after they no longer have a physical need for it.
Another illustration of this is that many drugs are incapable of producing physical addiction, yet they can be used addictively (compulsively) and even substituted for addictive drugs. Marijuana, LSD, amphetamines, and others can all be used addictively though they do not produce physical addiction in the way that sedative drugs (alcohol, heroin, barbiturates) can. Non-substance addictions like gambling or sexual addictions illustrate the same point. Since it is well-known that people can switch back and forth from drug to non-drug addictions like gambling or even other compulsive behaviors like shopping, it is clear that the physical component in some drugs is irrelevant to the nature of addiction. For a full discussion of the role of physical addiction see chapter six of "The Heart of Addiction".
In my new book, "Breaking Addiction," I take up perhaps the greatest current misconception about addiction: the notion that it is caused by a "chronic brain disease." This recently popular idea is based on studies of repetitive drug-seeking behavior in rats, which have been extrapolated to addiction in human beings. Rats who have been addicted to heroin respond with drug-seeking behavior when they are exposed to cues in the environment associated with the drug. This is very much like Pavlov's dogs who salivated at the sound of a bell after having heard the bell ring whenever they received food: a conditioned response. The new finding is that the brains of these rats are actually changed by their exposure to heroin, resulting in increased stimulation of the pleasure pathway of their brains by release of the excitatory chemical dopamine when the animals are exposed to drug-related cues. Hence, the researchers concluded that the rats' drug-seeking behavior when exposed to these cues was based on changes in their brains. However, this has nothing to do with addiction in people. Unlike rats, nearly all human addictive behavior is delayed in time from the point that the thought first crosses a person's mind. Commonly, this delay is hours or even days (think of waiting until the end of the day to get a drink, or driving for hours to get to a casino). Humans aren't responding to an immediate cue that temporarily floods their brains with dopamine. And of course, human addiction is triggered by psychological factors that are absent in rats. Indeed, addiction in people is a complex psychological mechanism as I've described. Finally, consider the Vietnam veterans I mentioned above. Like the rats, they were heavily exposed to heroin and became physically addicted. If the "brain disease" theory held true, they should have been doomed to repetitive drug-seeking behavior: addicts suffering from a chronic physical disease. But of course that is not what happened. It turns out that people are very different from rats.
Are all repetitive, dangerous activities addictions?
No. There are many factors that can lead to taking too many painkillers or drinking too much coffee, without the behavior being a true addiction. Among these factors that lead to abuse, but not addiction, are habit, peer pressure, even the setting in which the behavior is done. For example, casinos are built with no windows or clocks, and serve free alcohol, all to encourage excessive gambling. Gambling too much in that setting may not mean having an addiction. For a full discussion of non-addiction factors in excessive behavior see chapter nine of “The Heart of Addiction”.
Is it possible to have an addiction to the Internet?
One consequence of understanding addiction as I’ve described is that it helps explain why people can develop addictions focused on new activities, or switch from one to another. The displacement in addiction (the substitution of one activity for another) means that almost anything can be the focus of an addiction. In fact, it’s inaccurate to refer to being “addicted to” anything, since it isn’t the drug or the casino that magnetically pulls a person, it’s the drive to reverse feelings of helplessness inside people that leads them to seek these things. So, even though there was no such thing as addiction focused on the Internet 20 years ago, the Internet can be the focus of an addiction just as much as a drug or a piece of cake. For a full discussion of this topic see chapter ten of "The Heart of Addiction."