effectively filling the electrical outlet so the plug cannot be inserted. Blockade studies use chemicals to stop a particular receptor from firing.
Neuroimaging studies are used to provide images using brain-scanning technology to assess the effects of acute as well as long-term substance use on brain structure and functioning. A variety of brain-imaging techniques are used, such as the SPECT, MEG, PET, fMRI, and QEG. The SPECT, or Single Photon Emission Computerized Tomography, scan uses a radioisotope combined with a pharmaceutical that is injected into the patient to measure cerebral blood flow. The SPECT scan measures brain receptor activity and involves a long exposure—up to six hours—after an injection to conduct the brain scan.
With PET (Positron Emission Tomography) scans, a small amount of radioactive sugar is injected into a vein and a scanner is used to make computerized images that illuminate areas of increased glucose metabolism or receptor activity. It only requires a very short exposure.
The fMRI (Functional Magnetic Resonance Imaging) scan compares the difference in the blood flow in the brain between conditions and activity like thinking, seeing, touching, and hearing to find regions of the brain that are associated with one task and not another. It involves a very short exposure and can be repeated as often as desired because there’s no radiation.
The QEG (Quantitative Electroencephalogram) scan is also known as a “brain map.” It’s a computer analysis of a brain wave signal that’s compared against a reference database. It’s often used for research studies. A MEG (Magnetoencephalography) scan is a technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain. Its applications include localizing regions of pathology before surgical removal, determining the functions of various parts of the brain, and neural feedback.
To be an effective addiction therapist, you don’t have to completely understand all the subtleties of neuroanatomy and neurochemistry, but it is important to have a working familiarity with the parts and processes of the brain that are involved in the addiction cycle.
Stimulation, either electrical or chemical, of the nucleus accumbens and ventral tegmental area (VTA) is intrinsically rewarding, while stimulation elsewhere in the brain is not. The reward can be interrupted by severing the nucleus accumbens/frontal cortex fibers or by using medication like dopamine blockers. This is how researchers came to know that blocking can interrupt natural reward pathways.
There are patients in psychiatric hospitals, for example, who are on antipsychotic medications and often appear to lack emotion. Affect is the outward manifestation (facial expression, tone of voice, body language, etc.) of an emotion such as sadness, happiness, and excitement. Sometimes patients on certain psychiatric medications have very flat or unresponsive affect. Many of the psychiatric medications that block the neurochemistry that generates psychosis have an unfortunate side effect of also blocking the dopamine receptors. As a result, people on such medications may have difficulty experiencing pleasure, have a narrow emotional range, and have a very flat affect. However, without these medications, patients’ active psychosis returns.
As I mentioned earlier, dopamine is the primary transmitter that activates the brain’s reward center. It is the release and inhibition of reuptake/reabsorption of dopamine that generates experiences of pleasure and reward, and in turn, reinforces behavior. All mind- and mood-altering drugs ultimately act via the dopamine pathway. The longer someone uses alcohol or other drugs, the more of the substance(s) he or she needs to use in order to get the same high. This is the phenomenon of tolerance—a neuroadaptation wherein a substance no longer “works” and a higher dosage is required to achieve the same effect.
Neuroadaptation refers to the process whereby the brain compensates for the presence of a chemical in the body so that it can continue to function normally. The brain is always attempting to maintain a state of balance or homeostasis. The way it works is that the first time you use drugs, especially a stimulant, but with any kind of psychoactive drug, you get a big boost in your mood, you feel euphoria from the substantial release of dopamine in the brain’s reward pathway. And then the next time you do it, you still feel good, but not as high as the first time, and the third time, not as high as the second time. And then eventually, you never get the same high anymore and you start feeling lower and lower. That’s neuroadaptation.
Continued usage causes a gradual decrease in the number of receptors for the substance, along with a corresponding gradual decrease in the amount of available transmitters due to a feedback mechanism in the brain that seeks equilibrium.
The brain squirts out a certain amount of dopamine when you have sex or eat chocolate, but if you’re getting a lot more dopamine stimulation from drugs (exogenous stimulation), the brain stops making its own dopamine (from endogenous production). That is because the feedback loop is informing the brain there is more than enough dopamine “on board” already. The fact that the brain makes less dopamine explains why, when people stop using crystal meth, cocaine, or other stimulants, they generally feel depressed and lethargic for up to several weeks or even months. Their brain has been depleted of dopamine and they don’t have enough to maintain a normal mood. It’s like trying to drive a car with an empty gas tank.
The process goes like this: Continuing use creates an increased number of receptors and a decrease in the amount of available neurotransmitters. As the individual develops a tolerance to the drug, more of the drug is required to get the same high or rush. As the brain adapts to the presence of the drug through repetitive use, there is an increased need both for the drug and for greater quantities of it to maintain normalcy. These are the neurochemical dynamics of substance dependence.
Now let’s look at withdrawal from alcohol and other drugs. Addiction counselors and therapists have to help patients manage the abstinence state and help patients learn and practice recovery skills. As a physician I have to manage alcohol and other drug intoxication, and I have to manage patients in withdrawal.
How do we treat patients in various states of intoxication and withdrawal medically? The emergency rooms are full of people on all kinds of drugs. Many hospital emergency rooms just let the alcohol-intoxicated patients lie there in a subacute area and “sleep it off.” The nursing staff monitors their vital signs (blood pressure, temperature, pulse, and respiration) and makes sure that patients don’t go into acute withdrawal.
Some drugs can have a terribly uncomfortable withdrawal syndrome but they’re not medically dangerous. At least the withdrawal syndrome isn’t dangerous. A classic example is opiates/opioids. When people withdraw from heroin, Vicodin, Norco, or related drugs, the withdrawal is miserable and painful but in and of itself, it won’t kill anybody. No one dies from opiate withdrawal; they die from opiate overdose.
However, other drugs like alcohol, benzodiazepines, and barbiturates can have a very dangerous withdrawal syndrome that can lead to death. When a patient withdraws from alcohol or Xanax or Valium, especially in combination, it can become highly dangerous. Patients can suffer hallucinations, seizures, and DTs and die from alcohol and sedative-hypnotic withdrawal. The severity of the withdrawal always depends on how long someone has been taking the drug and the dosage he or she has been taking, but if the use of these kinds of drugs is discontinued abruptly, the result can be death from strokes and seizures.
Remember that tolerance is a physiological and neurological adaptation to the presence of a drug. After tolerance develops, abrupt discontinuation of the drug causes a recognized withdrawal syndrome to occur. Each class of drug results in a withdrawal syndrome that is characteristic of that class. There are recognized signs and symptoms that are very characteristic of opiate withdrawal syndrome, alcohol withdrawal syndrome, stimulant withdrawal syndrome, marijuana withdrawal syndrome, sedative-hypnotic withdrawal syndrome, nicotine withdrawal syndrome, etc. And when someone is getting off multiple substances, these withdrawal syndromes appear in combination.
All these
