Here we are at the beginning of February. How many New
Year's resolutions to go to the gym regularly, give up smoking, eat less sweets
and so on, have already been tossed quietly aside with other plans like
drinking less, along with the leftover Christmas booze? Change is hard – and
neuroscientists are now learning why.
Advances in neuro-imaging are now enabling researchers to look inside the brains of addicts and patients with addictive behaviours. What they are seeing in real-time is what gets patients hooked: how the brain's reward system -- based largely on the neurotransmitter Dopamine – provides thirst for more, while inhibitory control centres experience system failure.
And the pattern is similar across all kinds of behaviours -- from cocaine, alcohol and tobacco addiction to overeating. Changing your mind may be the first step towards breaking a habit, but altering the brain's neural machinery is the real challenge.
Petros Levounis, MD, director of the Addiction Institute of New York notes that drug-taking and other addictive behaviours "hijack" the brain's reward system.
In normal patients, dopamine plays a major role in motivation and reward, surging before and during a pleasurable activity -- say, eating or sex -- to make patients want to repeat a behaviour that's crucial to the survival of the species.
Dopaminergic pathways connect the limbic system, responsible for emotion, with the hippocampus, etching rewarding behaviours into the brain by creating strong, salient memories.
The problem arises when those ‘happy’ memories – and the craving to recapture them – take over a person's life. All the more difficult because these hijacked reward pathways are closely connected, geographically and anatomically speaking, with our memories and our emotions.
As the dopamine surge repeats and repeats, it gains speed, but the brakes begin to fail… Normal function in the brain's frontal lobes, responsible for inhibitory control and executive functioning (willpower) tends to decrease in addicts.
"Ultimately," Levounis says, "the war on drugs is a war between the hijacked reward pathways that push the person to want to use, and the frontal lobes, which try to keep the beast at bay. That is the essence of addiction."
These neural pathways have been well studied in the brains
of hardcore addicts. Now, researchers say they see similar pathways involved in
other self-destructive behaviours.
Several brain imaging studies of obese patients revealed similarities in brain activity -– or a lack thereof -- between patients addicted to cocaine or alcohol, and those ‘addicted’ to eating. Normally, the PET scan lights up when a contrast of radioactive glucose is metabolised, revealing an area of red activity in the centre of the brain.
But in both drug-addicted and obese patients, the scans show very little red activity, because there aren't enough receptors to which the radioactive glucose can bind. The decreased availability of dopamine receptors is the brain's way of coping with a constant dopamine overload.
Researchers say that if a person constantly has an excess of dopamine, the brain will down-regulate. Once the system is down-regulated, people have to do more in order to get the same amount of feeling in their normal state. Thus, obese patients want to eat more in order to compensate for their down-regulated system.
In other experiments, higher body mass index (BMI)
correlated with lower prefrontal cortex function -- the area associated with
inhibitory control, so that if a person is obese, they will have problems
controlling their eating behaviours. The studies also revealed that a higher
BMI was linked to a decrease in memory and executive functioning.
Ed Susman was 293 pounds when he joined a clinical trial for weight-loss drug Lorcaserin. He chronicled his year-long experience. Eating, to him, was a ‘compulsion’ -- as was biting his nails – something he had done since he was only 4 years old.
Over the course of the trial, not only did Susman lose 52 pounds, but also stopped biting his nails. Although he didn’t know if he was in the drug arm of the trial, he strongly suspected he wasn't experiencing a placebo effect. He believed he was on the drug because it controlled a 50-year compulsion. He says his nail-biting stopped cold.
The same did not quite happen with his eating habits, but he regained only 10 of the 52 pounds in the year after his participation in the trial ended.
The drug trial used Lorcaserin -- a combination of benzazepine and hydrochloride, two neurological agents reputed to improve willpower and ability to overcome compulsions. Along with two other investigative drugs to tackle obesity, the new medications have been described as ‘a bright light for the treatment of obesity’, says Levounis.
Basically, the effect of medications that act on the dopamine system is to cool down the reward pathways. There are two strategies for doing so: an agonist strategy, or an antagonist strategy. Treatment is typically twofold. For addicts, psychiatrists try to ‘cool down’ the reward pathways, often with medication. Then psychotherapy is used to diminish frontal lobes.
Researchers agree that psychotherapy is key to regaining
self-control, and it's the predominant treatment used in patients with
addictive behaviours. It can often reveal an underlying cause for an addiction
or compulsive behaviour – usually, anxiety or depression.
Acknowledging those problems may help change behaviours. Once they're realised, a patient can start working against them, with the help of the brain's own neuroplasticity. Essentially, neurons can disconnect and reconnect, or loosen their connections and tighten them, which often manifests in noticeable change.
Psychological insights can actually begin to change brain
chemistry and diffuse compulsions. If the issues are addressed, this can have a
positive impact on a person’s life that can change the chemistry of their
brain, creating a new psychological -- if not neurological -- structure that
can help regulate behaviour.
Although research on neuroplasticity is relatively young, the concept of ‘rewiring’ the brain is not new. In fact, all too often, the electricians’ metaphor is employed as an excuse for indulging and deferring those well-meant New Year's resolutions like "I can't stop eating that chocolate, I’m just not wired that way!”
Interested? You'll find the longer article here: http://www.medpagetoday.com/Psychiatry/Addictions/18207
Image: Weight Watchers
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