Pain, memory problems and nicotine addiction are formidable problems that have quite different consequences. But in terms of what’s happening in the brain that causes people to suffer from each, they share a close connection. And now scientists say one drug might be able to help people with all three of these problems.
Estimates suggest 2 million people in the U.S. suffered from an opioid abuse disorder in 2015 (the most recent year with data available), about 5 million Americans are currently living with Alzheimer’s disease and more than 36 million Americans are currently cigarette smokers (more than half of whom are trying to quit). A drug that helps with all three of these problems has the potential to affect the health of a lot of people in a significant way.
And because the new drug would work differently from ones that are currently available for these problems it (in theory) would be a lot safer for patients and have a lower risk of dangerous side effects, said Ayman K. Hamouda, assistant professor in pharmaceutical sciences and in neuroscience & experimental therapeutics at Texas A&M University.
“We’re not there yet. There is a lot to be done to understand [the pharmacology] of these compounds ― but we’re closer than ever to this goal,” he said.
The current class of drugs that help with nicotine addiction work by targeting brain receptors that react to nicotine in the first place. Varenicline (sold as Chantix) ― the only such drug approved for helping people quit smoking ― essentially replaces the effect of nicotine on these brain receptors, blocking the effect that causes people to keep craving cigarettes. But the problem is that these drugs affect other receptors, too ― not just the ones that are linked to nicotine addiction, Hamouda explained. This has led to some reports of changes in behavior, altered mood and suicidal thinking and sleep problems. And only about 22 percent of smokers who use the drug end up actually quitting cigarettes.
Instead, Hamouda’s team is developing a drug that would actually boost brain activity of the receptors that are linked to memory, pain signals and nicotine addiction. That boost helps the receptors that are working properly to function better, compensating for the activity of impaired receptors. The approach is like giving your brain a push, rather than making a chemical change, which the researchers suspect will mean fewer side effects for patients.
”We think our approach will be safer because we’re not changing the pattern of neural activity,” Hamouda explained ― meaning patients would not encounter the same serious side effects they currently do when taking drugs to help with pain and smoking cessation. “Instead, we’re changing the extent of neural activity so that the same signal that the brain designed is now at a higher level.”
How to target the right brain activity
Hamouda and his team recently identified an important clue about brain structures that play a role in these problems, putting them one step closer to designing this type of drug.
Researchers have known that one type of receptor in the brain ― nicotinic acetylcholine receptors ― are responsible for why people get addicted to the nicotine in cigarettes as well as a lot of other functions from making your muscles work to controlling attention, memory and learning.
Think of each receptor being made up of Lego blocks, Hamouda explained. There are only a dozen different types of Lego blocks that make up all the receptors ― so the combinations are different for some receptors than for others. In real life, the “Lego blocks” are the structures that make up the receptors. And the different structures determine what function the receptor has in the body.
Scientists want to develop a drug to more specifically target only the receptors that are causing problems, but they still don’t understand enough about the structures of these receptors to make drugs that work on one versus another.
Now in their latest study, Hamouda’s team was able to identify a structural difference in one type of receptor (the type that contributes to nicotine addiction, cognitive problems and pain), Hamouda said. That means such a drug might be effective in helping patients with all of these problems, he added. Though it’s important to note there is still a lot of work to do to design and develop the drug, and test it for all of these issues. An approved drug is still likely many years away.
Even when this drug comes out, it won’t be a cure-all for addiction
No one drug is going to be able to help everyone fighting nicotine addiction, cognitive decline and pain, Eric Strain, director of the Center for Substance Abuse Treatment and Research at Johns Hopkins Bayview Medical Center, told HuffPost.
“Substance abuse disorders are really complicated conditions ― and it’s not quite as simple as, say, treating somebody with a pneumonia where you get the right antibiotic to target the organism that’s producing that infection and you can then cure that person of that pneumonia,” he said.
Addiction and drug abuse disorders are due in part to things happening within our bodies (such as changes in the chemical systems and circuits in the brain that affect reward responses and cravings), Strain said. But there are factors outside our bodies in our environment ― from peer pressure to availability to the people around us ― that influence whether we start using and/or abusing problematic substances in the first place and whether we continue using these substances, he explained.
The work being done to develop these types of drugs that help with all of these outcomes ― like the new strategy being pursed by Hamouda’s team ― is exciting, Strain added. “Developing more selective medications would be terrific.”
But he cautions we’re far from a time when these drugs will be available. And if and when they are, they likely won’t be a cure-all for everyone ― especially when it comes to substance abuse disorders.