The Addicted Brain (16 page)

This information tells us that the influence of our genes on drug taking varies from person to person, and that each person has a different level of biological vulnerability. Most people exposed to addicting drugs do not become addicts. Data shows that the likelihood of addiction is partly due to hereditary factors—our genes. But environmental factors (for example, the availability of drugs, high stress, emotional problems, and peer pressure to use drugs) are essential. Although genetics might account for as much as 20–40 percent of our vulnerability,
²
it isn’t correct to blame just our genetics for our level of drug use.

Drug use in individuals is often associated with a variety of emotional problems such as depression, anxiety, schizophrenia, post-traumatic stress disorder (PTSD), and other complicated problems referred to as antisocial personality disorders and conduct disorders. In one study, between 21 and 32 percent of nicotine-dependent subjects had an additional mental health diagnosis. Although this made up only 7.1 percent of the population, they consumed more than 34 percent of all the cigarettes in the U.S.
³

Some of these mental health disorders might either be caused by, or exist independently of, substance use. In any case, they can facilitate drug use—a justification for treating both problems when an individual suffers from both drug use and a mental health disorder. Sometimes, withdrawal or cessation of drug use can precipitate problems such as anxiety; in this instance, treating the mental problem can make drug addiction treatment more successful. Related to this, it has been suggested that at least some drug addicts begin using drugs to self-medicate and treat problems such as anxiety. This means that if you use addicting drugs, you might have a mental health problem in addition to the use of drugs. If you do, then dealing with that will reduce your vulnerability to drug taking. Mental problems can
weaken our resolve to deal with other issues (such as drug use) in our lives. They can distract and exhaust us, and possibly lead to self-medicating, which might be problematic. Although treating our ills is, of course, important, a doctor’s involvement is often needed, particularly when abusable drugs are involved.

Many studies show a correlation between personal temperament and drug use. For example, impulsivity, physical activity level, having difficulty sitting still, and the tendency to become emotionally upset have been correlated with higher drug use. On the other hand, having a more positive mood and a desire to be around people have been
negatively
correlated with drug use. Often, personality traits in
adolescence
correlate with higher drug use as
adults
. This is clearly an important topic and an active area of research.

Availability of drugs is obviously a major factor in becoming a drug user. If drugs were not available, then there would be no users. But, drugs are available in many places, and staying away from drugs is essential for recovering addicts (and everyone else, of course). For example, Alcoholics Anonymous focuses on staying away from alcohol and provides a support system for doing so. Availability can have a marked and destructive effect on an entire community.

Adolescents are a special case. Being exposed to drug use or participating in drug use at an early age has an impact on drug use later in life.
Figure 8-3
shows that there is a relationship between the age at which drugs are first used and the likelihood that the same person will become drug dependent at some later time in his or her life.

Figure 8-3. Adolescent drug use increases the likelihood of drug dependence later in life. (Reprinted from
Journal of Substance Abuse
, Vol. 10, Bridget F. Grant and Deborah A. Dawson, “Age of onset of drug use and its association with DSM-IV drug abuse and dependence: Results from the national longitudinal alcohol epidemiological survey,” pp. 163-173, Copyright (1998), with permission from Elsevier.)

The data shows that when drugs are used before about 17 years of age, the likelihood of dependence at some time later in life rises dramatically.

There is plenty of physiologic evidence that the adolescent brain can be more responsive to drugs than adult brains. For example, dopamine neurons (which many drugs affect) in the adolescent rat are more sensitive to stimulation than those in adult rats (see
Figure 8-4
). The young neurons are different; their response to a particular stimulus is greater than that of an older neuron.

Figure 8-4. Dopamine neurons in the Ventral Tegmental Area (VTA) in young mice are more responsive than those in adult mice. The dopamine neurons in the VTA, in a slice of mouse brain, were stimulated for 2 seconds (shown by elevated line on bottom trace) and the elicited action potentials were recorded. An individual action potential is shown as an upward line rising sharply from the baseline. There are many more action potentials in young neurons than in adult neurons. Young dopamine neurons are capable of responding more than adult neurons to the same stimulus. The VTA is a region containing dopamine cell bodies that is relevant to developing addiction. (Reprinted from
Biochemical Pharmacology
, Vol. 78, Andon N. Placzek, Tao A. Zhang, and John A. Dani, “Age dependent nicotinic influences over dopamine neuron synaptic plasticity,” pp. 686-692, Copyright (2009), with permission from Elsevier.)

This is definitely a message for parents and communities, and it makes young people an important target for prevention efforts.

In many ways, drug abusers are among the least capable of stopping drug use. As they become intoxicated, their normal, cognitive and self-regulating abilities become compromised. For example, as they become drunk on alcohol, it becomes more difficult to stop drinking for several reasons. One reason is that the person is less aware of what he or she is doing, and the cognitive function, which is needed to help assess the situation, is impaired. Drug use can impair the function of brain regions such as the orbitofrontal cortex and anterior cingulate gyrus that are involved in judgment, decision making, and inhibition of unwanted activities like drug taking. These impairments contribute to a lack of control, compulsive drug taking, and a general impairment of judgment that favors relapse to drug use. This was shown by
Dr. Edythe London and colleagues and others in a gambling task; drug abusers were much more likely to make bad decisions that resulted in long-term losses.
⁴
Taking drugs can make things worse and result in a nasty, downward spiral.

What if you are right now saying, “Oh my gosh, I have a lot of those factors for vulnerability?” Or, what if you know somebody important to you who seems to be loaded with vulnerability? Or maybe some friends are trying to stop drinking but have no idea about these factors and what they mean for them. Well, now is the time to pay attention and listen up.

These are “risk” factors, and risk is not certainty. Risk is about an increased likelihood. Nevertheless, thinking about risk factors can be helpful. If certain factors apply to someone, then he or she has to work extra hard in controlling these and other factors. For example, someone who has a strong family history of drug dependence might have a hereditary vulnerability that, of course, can’t be avoided. However, this just means that the person would have to work at other factors like avoiding places where drugs are available, avoiding friends who use, and seeking positive support from counselors, clergy, friends, and family members. The more risk factors that one has, the more vulnerable he or she is. So, working at controlling the risk factors that one can influence is important. Life is short, and strengthening positive and healthy habits will mean a lot. When in risky situations, being aware of the danger of drugs and being prepared to say no to drugs are crucial to combating risk factors.

Here is an interesting story. Jonathan Haidt tells us in his book
⁵
of the metaphorical concept of the “elephant and the rider” to describe our control of emotional drives and actions. Both the elephant and rider
are found in each of us and represent different aspects of our psyche. The rider is intelligent with a grip on the reigns that guides the elephant in its tasks (or through life). The rider can see the overall task, is responsible for it, and has the judgment and skills to deal with it. The rider is associated with our conscience, our conscious and controlled thinking, and planning for the future. Perhaps the rider is like Freud’s super ego and ego.

The elephant on the other hand, is the rest of our psyche; it includes fears, emotions, intuitions, and visceral reactions. It contains the reward and reinforcement centers in our brains, and embodies the powerful drives that lurk in the old parts of our brain that have helped our species survive. Like the rider, the elephant has knowledge, but of a different kind. It is more like Freud’s id or primitive drives. In our psyche, the elephant represents drives and appetites that are perhaps more subconscious than conscious.

When a skilled rider teams with a strong elephant, both can do well and accomplish much. However—and here is the point—the elephant within us, being so big and powerful in comparison to the rider within us, will do whatever it wants or feels it must under certain circumstances. If the elephant is suddenly attacked by a hungry tiger, it will react powerfully and pay no attention to the rider no matter how knowledgeable the rider is about fighting tigers. When a stimulus strikes the elephant as overwhelmingly dangerous, reflexive drives take over and the rational thinker is left struggling for control. The rider is vulnerable to losing control of the elephant.

This is one way we can think of drug addiction or abuse. Drugs are seen by both the rider and the elephant within us, and the question is, who will control our actions? If our appetites for drugs dominate, the elephant might take over. The primitive drives and appetites that have ensured the survival of our species are very strong. If the sensible rider has an influence over the elephant and can guide its actions, we might avoid drugs. Whether we take drugs or not depends on our overall vulnerability (how much the elephant
wants it versus how skilled and determined the rider is to avoid it). A major factor is how well the rider has been trained, and on how well the rider has trained the elephant within
.
Responding to crises can be prepared for, at least to some degree.

What about the responsibility of the rider for the elephant? We all know that we cannot totally give up responsibility for control of our elephant. If we take drugs and have an accident, then we are responsible. If we take illegal drugs and have to face the law, it is our fault. It is clear that we must take responsibility to maintain law and society. But perhaps there are some circumstances—the equivalent of the appearance of a hungry tiger—where absolute control by the rider is diminished and his responsibility is reduced. Dealing with these difficult circumstances requires wisdom and often help.

The major message of this chapter is that individuals might have to work hard to take care of themselves. If they have risk factors for becoming a drug user, then they need to pay attention to them. If there are some that they can’t avoid, like genetic factors or drugs in the environment, then they have to work doubly hard at controlling the risk factors that they can. If drugs are being sold or are available, then avoiding those places and people and practicing the ability to say no is important. A conference with a physician or another professional would be helpful.

¹
From
NIDA Notes
, “New Techniques Link 89 Genes to Drug Dependence.” Vol. 22, No.1, September 2008.

²
For example, see Table 1.5 in Koob, G.F. and M. Le Moal.
Neurobiology of Addiction
. London: Academic Press, 2006.