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Study issues warning: Opioid inhibitor naltrexone (often used to treat addictions) can reduce feelings of social connection

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Sci­ence has long known that hav­ing pos­i­tive social con­nec­tion is impor­tant to a hap­py and healthy life. But less is under­stood about how our brains sup­port and encour­age con­nect­ing with oth­ers.

While pri­or research has sug­gest­ed oxy­tocin plays a role in nur­tur­ing and trust­ing oth­ers, there­by strength­en­ing social bonds, many researchers also sus­pect that brain opi­oids are impor­tant to social con­nec­tion. Opi­oids are nat­u­ral­ly occur­ring brain chemicals—perhaps the most well-known being endorphins—that cause plea­sur­able sen­sa­tions in the body and encour­age us to enjoy what­ev­er we are expe­ri­enc­ing. It’s pos­si­ble that opi­oids also cause the warm feel­ings we get in social encoun­ters, there­by encour­ag­ing us to be more engaged with oth­ers.

But, accord­ing to a recent study, the role of opi­oids may be a lit­tle more com­pli­cat­ed than that—and there are prac­ti­cal impli­ca­tions for how we treat drug addic­tion.

Opioids target social connection

– Nal­trex­one, a med­ica­tion that inhibits opi­oids’ impact

Par­tic­i­pants unaware of the study’s pur­pose took an opi­oid inhibitor called nal­trex­one for a four-day tri­al and a place­bo for anoth­er four-day tri­al in ran­dom­ized order, with a break in between to clean out their sys­tem.

Over the course of the exper­i­ment, the par­tic­i­pants kept dai­ly track of how social­ly con­nect­ed they felt and how pos­i­tive their moods were. On the fourth day of each tri­al, they com­plet­ed a task in the lab, read­ing six very kind mes­sages that loved ones had sent to the researchers in advance, unbe­knownst to the participants—messages like “I am so grate­ful to have you in my life” and “Thank you for lov­ing me at my worst.” Then par­tic­i­pants report­ed how con­nect­ed they felt toward the mes­sage writer, as well as how good it felt to read the mes­sages.

After­wards, the researchers com­pared how much social con­nec­tion par­tic­i­pants had in their every­day lives, as well as how much of a sense of con­nec­tion they felt dur­ing the lab task. Results showed that par­tic­i­pants felt more con­nec­tion in both every­day activ­i­ties and dur­ing the lab task when they were on place­bo than when on nal­trex­one, sug­gest­ing that nal­trex­one was block­ing endor­phins impor­tant to social close­ness.

We test­ed a long-stand­ing theory—based on ani­mal data—that sug­gests brain opi­oids con­tribute to feel­ings of con­nec­tion. But no one had shown that rela­tion­ship causal­ly in humans,” says the study’s lead author, Tris­ten Ina­ga­ki.

She and her col­leagues also found that tak­ing nal­trex­one did not decrease pos­i­tive emo­tion in every­day life, even though it affect­ed the par­tic­i­pants’ sense of con­nec­tion to oth­ers. This sug­gests that opi­oids play a tar­get­ed role in social con­nec­tion that is above and beyond just feel­ing good.

 

All of this work is try­ing to get at what makes us feel con­nect­ed to oth­ers and how we can help those who are feel­ing lone­ly or social­ly iso­lat­ed.”
Tris­ten Ina­ga­ki

 

Opi­oids seem to affect our response to the most reward­ing or most plea­sur­able stim­uli in the envi­ron­ment,” says Ina­ga­ki. “For humans, being social or being around your loved ones is like­ly to be the most salient reward­ing stim­uli.”

Ina­ga­ki points to oth­er research show­ing that opi­oids reduce the sense of con­nec­tion peo­ple get from sim­ply hold­ing a warm object, but don’t affect rat­ings of plea­sure. This lends fur­ther sup­port to her own find­ings.

The mech­a­nisms for opi­oids must be smarter than we think,” she says.

The addiction connection

While much of the research on opi­oids and social con­nec­tion is pre­lim­i­nary, Ina­ga­ki thinks her study war­rants atten­tion, giv­en that opi­oid inhibitors like nal­trex­one are often used with patients to treat addic­tions. Though nal­trex­one may indeed inhib­it the high peo­ple feel when tak­ing illic­it drugs—and there­by help them kick the habit—it may also shape their social rela­tion­ships.

Lots of research shows that peo­ple real­ly need their social net­works when they’re deal­ing with major stressors—addiction being a major stres­sor,” says Ina­ga­ki. “So, if the drug pre­scribed to help some­one over­come addic­tion is also reduc­ing how con­nect­ed they feel toward oth­ers or reduc­ing the time they spend with oth­er folks, that’s not a great out­come.”

At the very least, she says, clin­i­cians should be aware of the poten­tial down­side of using nal­trex­one, so they can warn patients about social side effects and make sure patients are remain­ing social­ly inte­grat­ed.

While Inagaki’s find­ings are intrigu­ing in their own right, they may also be rel­e­vant to under­stand­ing the cur­rent opi­oid addic­tion. Research has shown that genet­ic dif­fer­ences in opi­oid recep­tors lead to increased risk of addic­tion, just as her research sug­gests block­ing opi­oid recep­tors decreas­es social close­ness. Doesn’t that sug­gest feel­ings of dis­con­nec­tion and addic­tion could be relat­ed?

Ina­ga­ki thinks so.

One off­shoot of the opi­oid the­o­ry is that those with low opi­oid tone show exag­ger­at­ed respons­es to social stressors—like feel­ing lone­ly, feel­ing social­ly reject­ed,” she says. “So, the idea that neg­a­tive social encoun­ters could pro­duce a risk fac­tor for all kinds of men­tal health issues, includ­ing addic­tion, is being re-appre­ci­at­ed right now.”

While the jury is still out, Ina­ga­ki and her team will con­tin­ue to research the role that opi­oids play. She is cur­rent­ly run­ning a neu­roimag­ing study to see how nal­trex­one impacts neur­al activ­i­ty in response to social con­nec­tion. She hopes that her research will help inform how we humans bond, with impli­ca­tions beyond addic­tion.

“All of this work is try­ing to get at what makes us feel con­nect­ed to oth­ers and how we can help those who are feel­ing lone­ly or social­ly iso­lat­ed,” she says. “My hope is that peo­ple who are strug­gling don’t have to turn to drugs.”

Jill Sut­tie, Psy.D., is Greater Good’s book review edi­tor and a fre­quent con­trib­u­tor to the mag­a­zine.  Based at UC-Berke­ley, Greater Good high­lights ground break­ing sci­en­tific research into the roots of com­pas­sion and altru­ism. Copy­right Greater Good.

The Study

Opi­oids and social bond­ing: nal­trex­one reduces feel­ings of social con­nec­tion (Social Cog­ni­tive and Affec­tive Neu­ro­science):

  • Abstract: Close social bonds are crit­i­cal to a hap­py and ful­filled life and yet lit­tle is known, in humans, about the neu­ro­chem­i­cal mech­a­nisms that keep indi­vid­u­als feel­ing close and con­nect­ed to one anoth­er. Accord­ing to the brain opi­oid the­o­ry of social attach­ment, opi­oids may under­lie the con­tent­ed feel­ings asso­ci­at­ed with social con­nec­tion and may be crit­i­cal to con­tin­ued bond­ing. How­ev­er, the role of opi­oids in feel­ings of con­nec­tion toward close oth­ers has only begun to be exam­ined in humans. In a dou­ble-blind, place­bo-con­trolled, crossover study of nal­trex­one (an opi­oid antag­o­nist), 31 vol­un­teers took nal­trex­one for 4 days and place­bo for 4 days (sep­a­rat­ed by a 10-day washout peri­od). Par­tic­i­pants came to the lab­o­ra­to­ry once on the last day of tak­ing each drug to com­plete a task designed to elic­it feel­ings of social con­nec­tion. Par­tic­i­pants also com­plet­ed dai­ly reports of feel­ings of social con­nec­tion while on nal­trex­one and place­bo. In line with hypothe­ses, and for the first time in humans, results demon­strat­ed that nal­trex­one (vs place­bo) reduced feel­ings of con­nec­tion both in the lab­o­ra­to­ry and in dai­ly reports. These results high­light the impor­tance of opi­oids for social bond­ing with close oth­ers, lend­ing sup­port to the brain opi­oid the­o­ry of social attach­ment.

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As seen in The New York Times, The Wall Street Journal, BBC News, CNN, Reuters,  SharpBrains is an independent market research firm tracking how brain science can improve our health and our lives.

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