Rehearsing Abstinence

First there was methadone. Then came bupropion, naltrexone, acamprosate, varenicline and a host of other promising drugs. But the latest anti-addiction medication doesn’t come in a pill; it runs on your PC. ScienceDaily reports on two interesting studies that attempt to help addicts using computer software. Both rely on cognitive behavior therapy, the psychological technique that involves identifying and modifying dysfunctional thought processes that lead to unwanted behaviors.

In the first study, researchers created a virtual reality environment in which alcoholic patients could be exposed to the same cues and stimuli that normally elicit cravings.

[The] VR environments, developed with a company called Virtually Better, feature different scenarios that an addict may find challenging: a bar with imbibing patrons, a house party with guests drinking and smoking, a convenient store with cigarettes and alcoholic beverages within reach, a designated smoking section outside of a building or a room with an arguing couple. The environments use actors in each scene as opposed to computer-generated characters. In addition, the study added another layer of realism. A device sprayed the air with scents the participant may encounter in the various scenarios–cigarette smoke, alcoholic beverages, pizza or aromas associated with the outdoors.

In the second study, researchers developed a computer program that places patients in hypothetical situations and coaches them on how to avoid relapse.

Those assigned to computer-assisted training were exposed to six lessons, or modules, that they accessed from a computer located at the treatment program. Each module included a brief movie that presented a particular challenge to the subjects’ ability to resist substance use — such as the offer of drugs from a dealer. The narrator of the module then presented different skills and strategies to avoid drug use and also show videotapes of individuals employing those strategies.

Unlike the first study, the second scored participants for successful abstinence. Researchers found that subjects who received computer training had fewer positive drug tests compared to traditional counseling alone.

One problem with pharmaceutical interventions like varenicline or naltrexone is the way in which they shift responsibility away from the patient (It’s not me, it’s my brain!). By conceptualizing addiction as purely biological, patients may lose faith in their own willpower. Emerging computer-based interventions are promising because they encourage addicts to take control of their own cravings. Some combination of these approaches may prove most useful in the long run.

Method Of The Month: Osmotic Pumps

This post is the sixth in a series that aims to educate readers about the tools that are used in neuroscience research. Previously we discussed Radioactive Binding Assays, Novel Object Recognition, Calcium Imaging and EEG.

Currently I am running a study that examines the effects of chronic nicotine on sensory processing in mice. While I don’t mind coming into the lab on weekends, the prospect of visiting my animals 24/7 to inject nicotine wasn’t exactly practical. I could give daily or twice daily injections, but even that doesn’t really come close to approximating the behavior of human smokers.

That’s why we turned to a company called Alzet that manufactures miniature pumps for drug delivery in laboratory animals. These pumps can deliver small volumes of drug solution at a controlled rate over a period of up to six weeks. We opted for the 2002 model, with a reservoir volume of 0.2 mL and a flow rate of 0.5 µL/hr.

They are pretty easy to use: Just fill up the reservoir with concentrated drug solution and pop on the cap. Then, anesthetize the rodent and cut a small slit in its back using standard aseptic techniques. After opening a small cavity for the pump with a hemostat, insert the device and close the opening using medical staples.

After implanting these pumps subcutaneously, I couldn’t help but wonder if these things were actually going to work. How could a little piece of plastic control the flow of drug solution so precisely? If they worked because of osmotic pressure, then shouldn’t the flow rate depend on the concentration of the dissolved drug? I knew that osmotic pumps were popular, but I couldn’t shake the irrational fear that these $20 devices were just one big scam.

The only way I could settle my nerves was by figuring out how the devices worked. Luckily Alzet’s website is relatively transparent about the mechanism. Now I know that the osmotic pressure difference is actually between the animal’s body and the “salt sleeve” that surrounds the drug reservoir. From their website:

ALZET pumps operate because of an osmotic pressure difference between a compartment within the pump, called the salt sleeve, and the tissue environment in which the pump is implanted. The high osmolality of the salt sleeve causes water to flux into the pump through a semipermeable membrane which forms the outer surface of the pump. As the water enters the salt sleeve, it compresses the flexible reservoir, displacing the test solution from the pump at a controlled, predetermined rate. Because the compressed reservoir cannot be refilled, the pumps are designed for single-use only.

The rate of delivery by an ALZET pump is controlled by the water permeability of the pump’s outer membrane. Thus, the delivery profile of the pump is independent of the drug formulation dispensed.

Pretty nifty, huh? Even niftier is the accompanying animation:

Now I am much more confident that my mice are indeed receiving the expected dose of nicotine. In retrospect my fears were misplaced, but in science it never hurts to be skeptical/cautious.

South Park on Addiction

Since Sen. Joe Biden proposed his Recognizing Addiction As a Disease Act of 2007, the relation of biology and choice has been a hot button issue. This South Park episode contains a searing critique of the addiction as disease model. As usual for the show, it’s over the top and controversial:

The Rational Addict

First Slate tried to convince us that drug addiction is simply a bad habit. Now, in an article by Tim Harford, they are trying to convince us that addiction is actually rational. I can’t claim to understand all the economic theory behind the claim, but if you care to investigate, here is a link to the original proposal.

Why Sally Satel is Wrong About Addiction

Earlier this year, presidential candidate Sen. Joe Biden (D-Del) sponsored a bill called “Recognizing Addiction as a Disease Act of 2007.” The bill proposes that the National Institute on Drug Abuse (NIDA) be renamed the National Institute on Diseases of Addiction and that the National Institute on Alcohol Abuse and Alcoholism (NIAAA) be renamed the National Institute on Alcohol Disorders and Health. Today, Dr. Sally Satel and Prof. Scott Lilienfeld published an article in Slate arguing that addiction should not be called a brain disease because it is self-inflicted, because it encourages resignation among addicts and because it dowplays the role of free will.

The first reason is incoherent, as many widely recognized diseases involve elements of self-infliction (diabetes, lung cancer etc). The latter reasons have some merit, but still face serious critiques. Moreover, they neglect the original intent of the bill: to combat the stigma associated with medical treatment.

As I have mentioned before, I quit cigarettes with a little help from Pfizer. Since then, I have encountered many people who have expressed a desire to quit. But when I offer my leftover Chantix prescription, the suggestion is invariably met with a look of disdain. Often they will tell me that they don’t need a pill to quit, an argument that bears disturbing similarity to the smoker’s tired mantra: “I can stop anytime I want.”

This stubbornness is nothing more than the simulacrum of free will. Many of my friends have quit cold turkey, but in reality, most heavy smokers cannot and will not quit on their own.

Satel implies that drug use is just like any other bad habit. But the difference here is one of degree. If a new study showed that people get lung cancer from biting their fingernails, most would have the self-control to stop immediately. Yet millions of smokers continue their behavior in spite of such information. Addiction, by definition, severs the natural mechanisms that allow our better judgment to control our behavior. Banking on free will to escape addiction is ill-conceived if addiction specifically impairs free will.

Perhaps some people can restore control with the help of God, but for most, this is not enough. Conceptualizing addiction as a moral crisis has the unfortunate effect of reducing the likelihood that addicts will seek medical treatment. Though today’s anti-addiction pills are only marginally better than quitting cold turkey, more effective treatments are on the way.

I never viewed my visit to the doctor’s office as defeat. In fact, I think of my request for Chantix as an exercise of willpower. Far from lulling me into resignation, conceptualizing my problem as a disease empowered me to seek out a cure.