The Addicted Brain (17 page)

³
Grant B.F. et al. “Nicotine Dependence and Psychiatric Disorders in the United States.”
Arch Gen Psychiatry
, 61:1107–1115, 2004.

⁴
Grant S. et al. “Drug Users Show Impaired Performance in a Laboratory Test of Decision Making.”
Neuropsychologia
, 38:1180–1187, 2000.

⁵
Haidt J.
The Happiness Hypothesis
. Cambridge MA: Basic Books, 2006.

“After the war, I was a hopeless alcoholic. But with help, I’d been clean for five years—not a sip of alcohol. Life was going so well for me. And then, the recession hit. Traumatic memories of the war returned, I lost my job, and now I’m about to lose my home because I can’t pay my mortgage. I’m so stressed out with trying to make ends meet that I’ve started drinking again.”

The more stress we experience, the more likely we are to use drugs. Although stress could have been included in the last chapter on vulnerability, its many interesting aspects warrant that a chapter be devoted to it. A dictionary definition of a stressor is a stimulus that is disturbing, like fear or pain, that alters normal bodily responses. When we are stressed, we are often tense, alert, and prepared to “fight or flee.” Stress produces important bodily changes that produce and reinforce the state of alertness and readiness. It is a complex response that has evolved in our bodies because it is important for our survival. However, it is a demanding response, and, as you know, unremitting and chronic stress can be emotionally and physically damaging.

How our bodies react to stress has been studied for decades. Stress begins with a stimulus in our environment that we interpret as threatening. It can involve hearing, seeing, touching, or all of these senses. The brain integrates these sensations, and as a result, the amygdala,
hypothalamus, and pituitary gland are activated. The amygdala and hypothalamus are parts of the brain associated with fear, stress, and the integration of bodily functions. The pituitary gland, which is controlled by the hypothalamus, is located just beneath the brain and releases hormones needed by the body. As part of the stress response, ACTH, a hormone released from the pituitary gland activates the adrenal glands, which in turn release the stress hormones, epinephrine and cortisol (see
Figure 9-1
). These hormones act throughout the body to prepare us for responsive action. Epinephrine increases heart rate and blood pressure to help the body meet the new demands. Cortisol increases blood sugar (glucose) to provide more fuel for the energy needed to deal with the stressor, and it does this by promoting the synthesis of glucose and by assisting in the metabolism of fat, protein, and carbohydrates that produce additional glucose. Chronic stress can affect many organ systems and leave us depressed, with aches and pains, nausea, dizziness, rapid heartbeat, and exhaustion. Stress can also suppress our immune system, leaving us with a greater risk for infection.

Figure 9-1. The body’s stress response. When someone is stressed, the brain’s stress pathways are activated such that the hypothalamus, found in the base of the brain, sends a chemical signal, CRH, to the pituitary gland, which sends another chemical signal, ACTH, to the adrenal glands (found near the kidneys). The adrenals secrete cortisol, which is the well known “stress hormone” into the blood. Cortisol then stimulates a metabolic response and circulates back to the brain to stop or regulate the release of chemicals from the hypothalamus and pituitary. This regulation is important so that this stress response is not a “runaway” process. Many addicts are hypersensitive to stress. (From
http://being.publicradio.org/programs/stress/particulars.shtml
and Roberto Osti, with permission.)

There are also emotional and mental responses to stress. Normally the frontal cortex, a highly evolved part of the brain, regulates reality testing, guides attention and thought, inhibits inappropriate actions, and regulates emotion. But under stress, other brain regions strongly come into play. The amygdala activates stress pathways in the hypothalamus and brainstem, which results in a loss of prefrontal cortex regulation and disposes us toward habitual responding rather than more cognitively controlled actions. So, stress causes a switch from reflective and modulated responses to emotionally driven reflexive responses.

Stressors can be personal, and what stresses one person might not stress another. There are many kinds of stressors. Environmental stressors include a natural disaster such as an earthquake, the 9/11 terrorist attack, or even such things as uncontrollable loud sounds or bright lights. Life changes such as divorce, job loss, or deaths in the
family can be serious stressors. The workplace can be stressful, and this is often related to how much control an employee has over his or her job and its conditions. Also, daily events such as a fender bender, loss of house keys, or theft of a purse or wallet can be very troublesome. Because of the dangers of stress and cumulative layers of stress, we must develop styles and support systems to help us handle it. Stress busters include play and exercise, meditation, improved diet, and medical care.

Stress can make us start using drugs or cause a relapse to drug use. Dr. Mary Jeanne Kreek of Rockefeller University in New York City has studied stress and relapse among the addicts of New York. She has said, “For six months or so, they (drug addicts) can walk past the street corner where they used to buy drugs and not succumb to their urges. But then all of a sudden they relapse,” she says. “When we ask them why they relapse, almost always they tell us something like, ‘Well, things weren’t going well at my job,’ or ‘My wife left me.’ Sometimes, the problem is as small as ‘My public assistance check was delayed,’ or ‘The traffic was too heavy.’”
¹
Many studies have shown that stress can promote relapse to drug use, even after long periods of abstinence. It can also worsen drug use in an active user and initiate or worsen other psychiatric disorders such as anxiety and depression, which can make drug use worse. Addicts are more susceptible to stress and are often already stressed. For example, withdrawal, or doing the work of avoiding drugs, can be stressful activities, and adding more stress can create a stress overload, resulting in relapse to drug taking. The act of just taking a drug can also be stressful.

Individuals suffering from post-traumatic stress disorder (PTSD) are of concern. They are people such as war veterans who re-live and re-experience horrible battle situations so vividly that they seem real. It’s a stress that occurs after the original trauma actually happened, but is so intense that it requires treatment. Of course, stress is subjective and PTSD does not have to come from wartime experiences. It can come from accidents, crimes, or other very bad experiences. PTSD sufferers are at greater risk for drug use as well.

Treating stress is important, but because of the danger of relapse, it is probably more important in a drug user.
²
However, medical supervision and much care are needed because some of the medications for treating stress and anxiety are themselves addicting.
Although stress is a risk factor for drug use, it is fortunate that it can be worked with, treated, and at least partially controlled.

A most amazing finding has been that stress in early life seems to change us—for the rest of our lives! This story began when scientists found an association between adverse events in early life, nicotine dependence in adults, and a strong relationship between household dysfunction when growing up and drug use as an adult. A variety of animal studies, by Drs. Michael Meaney, Darlene Francis, Paul Plotsky, and others, were carried out that supported these findings.

The author and his laboratory colleagues carried out the following experiment. Litters of newborn rat pups were divided into groups. Although there were several groups, we need to examine only two to make the point. One group of new born rats was separated from their mothers (referred to as dams) for 15 minutes a day (referred to as MS15), every day, during the first two weeks of life. A second group was separated from the dams for 3 hours every day (referred to as MS180) during the first two weeks of life. A separation of 15 minutes is not considered stressful, presumably because in nature, the mother must leave the nest for short periods to obtain food, and perhaps offspring are “programmed” to tolerate short separations. But a 3-hour separation is considered to be stressful for the pups. After the two weeks when the daily separations were carried out, all groups of pups were then placed with their mothers and raised just like all of the other animals in the vivarium until they were adults. There were no more separations until the pups were routinely weaned from their dams. When the pups were adults, they were tested to see how and if they would self-administer alcohol. The more stressed group (MS180) showed a greater preference for and a
greater intake of alcohol than the normal (MS15) group (see
Figure 9-2
). The same was found true for cocaine. A similar experiment was carried out by Dr. T.A. Kosten and coworkers, who separated pups from the dams for one hour. The separated animals, when they were adults, were more sensitive to cocaine in that they recognized lower doses of cocaine and self-administered it (see
Figure 9-3
). It is amazing that stressful experiences around the time of birth can influence drug taking much later in life when the animals are adults.

Figure 9-2. Early life stress affects alcohol intake when we are adults. Rat pups were separated from their mothers (dams) for either 15 minutes (MS15) or 180 minutes (MS180) everyday for two weeks right after birth. After these two weeks of daily separation, they were then treated like all other rats in the facility. But, when they became adults, they were tested for their inclination to drink alcohol. Although a 15-minute separation is not considered very stressful because dams in the wild must leave their pups for short times to get food, a 180-minute separation is considered stressful. As adults, the MS180 (more stressed) group had a greater preference for, and a greater intake of, alcohol than the MS15 (less stressed) group. This suggests that early life stressors can change our sensitivities to drugs and our behaviors for the rest of our lives! (With kind permission from Springer Science+Business Media:
Psychopharmacology
, “Effects of early maternal separation on ethanol intake, GABA receptors and metabolizing enzymes in adult rats,” Vol. 181 (2005) 11, Jaworski, JN, Francis, DD, Brommer, CL, Morgan, ET, and Kuhar, MJ, Figure 1.)

Figure 9-3. Stressed rats take more cocaine. A group of rats were stressed just after birth by removing them from their mother for just one hour per day for eight days. After the eight days of daily, brief stress, the rat pups were allowed to grow up like all other unstressed, normal rats in all other normal litters. As adults, the rats that were stressed as pups recognized cocaine at lower doses, and more readily self-administered cocaine! This shows that stresses around the time of birth can have effects that extend to adulthood, and that stressors in the perinatal period can result in greater drug taking as adults. (Reprinted from
Brain Research
, Vol. 875, Therese A. Kosten, Mindy J. D. Miserendino, and Priscilla Kehoe, “Enhanced acquisition of cocaine self-administration in adult rats with neonatal isolation stress experience,” pp. 44-50, Copyright [2000], with permission from Elsevier.)