MDMA as well as amphetamine and alcohol increase feelings of social closeness in healthy adults

Abstract

Psychoactive drugs such as alcohol and stimulants are typically used in social settings such as bars, parties or small groups. Yet, relatively little is known about how social contexts affect responses to drugs, or how the drugs alter social interactions. It is possible that positive social contexts enhance the rewarding properties of drugs, perhaps increasing their potential for repeated use and abuse. In addition, drugs may enhance the rewarding effects of social interactions by increasing feelings of social closeness and connectedness. To examine these relations, we investigated the effects of several drugs (MDMA, methamphetamine, alcohol) on feelings of connection between two strangers engaged in a conversation. We also investigated feelings of connection between two participants who discussed either ‘shallow’ or deeper topics in two conversations, without any drugs. All four conditions: deeper conversations, MDMA, methamphetamine and alcohol significantly increased feelings of connection and closeness compared with control conditions (small talk or placebo). We postulate that these feelings of connection could contribute to the drugs’ rewarding effects when the drugs are used in social contexts.

Introduction

People typically use psychoactive drugs in the presence of other people¹. While there are many possible reasons for this, it is likely that there are bi-directional facilitatory effects between effects of drugs and positive social experiences. That is, drugs can enhance the enjoyment of social interactions, and conversely, the presence of others can enhance the rewarding effects of drugs. These reciprocal interactions are poorly understood, and difficult to study because they are dynamic and situation-dependent. We have used a standardized procedure involving semi-structured dyadic conversations to investigate interactions between drugs and social contexts. Our studies have focused on one important outcome measure, that is, whether the drugs increase feelings of social closeness and connectedness during conversations with strangers.

To measure effects of drugs on social closeness, we have used a component of a standardized closeness-building procedure² in which participants engage in a 45-min conversation with a stranger. The procedure was developed without drugs, to show that it was possible to induce feelings of closeness between conversation partners based on the topics they were given to discuss. Specifically, pairs of strangers who were instructed to discuss more personal (‘deep’) topics reported feeling closer and more connected than those who discussed small talk (‘shallow’) topics. We have used the small talk version of this task to determine whether single doses of drugs similarly increase feelings of closeness and connectedness.

We tested three drugs. 3,4-methylenedioxymethamphetamine (MDMA) is an amphetamine-like drug that is often referred to as an empathogenic, entactogenic or, most recently, connectogenic drug because of its pronounced prosocial effects^3–5. Methamphetamine is a prototypic stimulant drug that increases certain social behaviors^3,6, and alcohol is known to facilitate social interactions⁷, although its effects on feelings of social connection have received little attention (Molla et al, in press ⁸). In addition to the three drug studies, we tested a separate group of participants who engaged in small talk vs. deep talk procedure to provide a metric against which to test the effects of the drugs (unpublished). In all four studies, we also obtained measures of the semantic content of the conversations, using the text analysis tool Linguistic Inquiry and Word Count⁹. This measure provided information on whether the drugs (or topics) changed the content of the conversations, which could, in turn, affect feelings of connection.

Procedure

We present data from four studies. The first study was a non-drug study (ND), in which healthy volunteers (N = 37) engaged in two 45-min conversation with different partners, discussing either deep (Deep Talk) or shallow (Small Talk) topics, in randomized order. After the conversations, participants completed questionnaires reporting how meaningful they found the conversation, whether they felt close to their partners, and whether they liked, or felt liked by, their two partners. This study was designed to replicate the findings reported by Aron et al. (1997). The second and third studies (Molla et al. 2023) examined effects of MDMA (100 mg; N = 17; MDMA study) or methamphetamine (20 mg; N = 19; MA study), compared to placebo, on feelings of closeness. In these studies healthy young adults received the drug in a laboratory setting under double blind conditions, and engaged in the small talk condition only. The fourth study (Eth Study) investigated the effects of a moderate dose of alcohol (0.8 g/kg for men and 0.7 g/kg for women) on feelings of closeness with a partner, using the small talk condition⁸. Small talk was chosen rather than the deep talk condition with the drugs to maximize the likelihood of detecting drug-induced increases, and to minimize potential ceiling effects in connectedness ratings. The drug and placebo sessions were separated by at least 4 days (MDMA) or 3 days (MA and Eth). There were minor procedural differences between the studies, making it difficult to draw direct comparisons. In the ND, MDMA and MA studies, the conversation partners were same-sex confederates, whereas in the Eth study, conversation partners were co-participants in the study with no restrictions on sex of the partner. To be eligible for the MDMA study only, participants had to report having used MDMA or a psychedelic drug at least once in their lifetime. The Eth study consisted of four sessions, in which participants received ethanol twice and placebo twice, with four different partners. Their data from the two ethanol and placebo sessions were averaged. Another reason it is difficult to compare across the three drug studies is because each study used only a single dose of drug.

Participants

Participants were aged 18–35 years old, except for the alcohol study which had a minimum age of 21. They were healthy men and women who reported light to moderate use of drugs (Table 1). Participants in the drug studies underwent a psychiatric screening interview, EKG and physical examination. Informed consent was obtained from all participants and the research was performed in accordance with the Declaration of Helsinki. The studies were approved by the University of Chicago Biological Sciences Division Institutional Review Board.

Table 1.

Participant demographic characteristics and drug use histories for non-drug MDMA, MA and alcohol studies.

Participant demographics	Non-drug study	MDMA study	MA study	Alcohol study
	n or Mean (SD)	n or Mean (SD)	n or Mean (SD)	n or Mean (SD)
Participants
Total (M/F)	37 (19/18)	17 (11/6)	19 (8/11)	37 (17/20)
Race
American Indian/Alaskan	-	-	-	1
Asian	5	2	3	7
Black or African American	2	0	2	3
Hispanic	-	-	-	6
White or Caucasian	26	9	14	20
Other/More than one race	4	6	0	4
Not reported	-	-	-	2
Age	23.9 (3.4)	26.6 (3.2)	22.1 (3.0)	25.8 (3.6)
BMI	-	22.4 (2.7)	22.3 (3.0)	23.2 (2.7)
Education in years	15.6 (1.8)	16.0 (1.0)	15.0 (1.2)	16.1 (1.4)
Current Drug Use
Caffeinated drinks per day	-	1.6 (1.0)	0.9 (1.1)	1.3 (0.7)
Cigarettes per day	-	0.4 (1.0)	0.1 (0.2)	0.4 (0.5)
Alcoholic drinks per week	2.9 (4.1)	2.6 (2.0)	2.1 (1.7)	2.0 (1.1)
Cannabis use in past 30 days	-	4.9 (8.2)	2.1 (3.7)	4.6 (4.5)
Lifetime Drug Use ( n  individuals who used at least once)
Sedatives/Tranquilizers	-	3	0	1
Stimulants (other than MDMA)	3	13	1	10
Opiates	-	2	1	1
Psychedelics/Hallucinogens	13	17	6	19
MDMA	4	17	3	11

Study sessions

Sessions were conducted in a comfortable laboratory environment. Participants were first tested for recent drug use and pregnancy (women). The drug or placebo was administered in randomized order under double blind conditions, with adequate days between sessions to allow for drug clearance. During the 4 or 5-hour sessions, participants were alone except for the 45 min conversation with a stranger. The conversation partners were either fellow participants or confederates. During the conversations, the two partners were given lists of suggested topics to discuss, one list every 15 min. They could skip topics if they wished, but they were told to take turns addressing the topics with each other. The topics provided in the drug studies resembled small talk, referred to as ‘shallow’. In the non-drug study, participants engaged in the small talk conversation on one session and on the other session were given topics that became progressively ‘deeper’ over the three 15 min blocks. The order was randomized. At the end of the sessions subjects completed questionnaires reporting on their experiences during the conversation. Participants also completed other questionnaires during the sessions to measure mood and subjective state. These are presented in the original papers³ but not reported here.

Outcome measures

1. Conversation Questionnaire¹⁰: This questionnaire assesses the intensity of the connection between the partners. Responses ranged from “Not at all” (0) to “Extremely” (9). Participants completed items from this questionnaire at the end of the sessions, including ratings of perceived closeness and conversation meaningfulness.

2. Connection During Conversations Scale (CDCS)¹¹: This 16-item questionnaire assesses connection experienced during an interpersonal interaction, including perceived partner care. Responses ranged from “Strongly disagree” (1) to “Strongly agree” (7). Participants completed these ratings at the end of the sessions.

3. Inclusion of Other in Self Scale (IOS)¹²: This single-item measure assesses the degree of connection felt with partners. It consists of 7 pairs of circles with varying degrees of overlap, ranging from no overlap (1; “no connection”) to most overlap (7; “felt extremely connected”). Participants completed these ratings at the end of the sessions.

4. Linguistic Inquiry and Word Count (LIWC): LIWC provides a quantitative analysis of the frequency and content of words used during the conversation. For this analysis, conversations were transcribed and analyzed using standardized methods^9,13.

Statistics

Ratings of closeness were analyzed using a linear mixed effects model with the lmer package in R. Fixed effects were drug/talk condition, age and sex, and participants were entered as random effects. Main effects of drug/talk condition are reported for each study, along with any drug/condition x age or drug/condition x sex interactions. LIWC was compared within each study (i.e., small vs. deep talk in the ND study, or placebo vs. drug in the three drug studies) using two-tailed paired t-tests. Because of the procedural differences between the studies, the data were not compared statistically across studies.

The criterion for significance was p < 0.05.

Results

Demographic characteristics

The participants in the four studies were young adults, aged 18–35 (Table 1). They reported light-to-moderate drug use, and most had completed college.

Ratings of closeness

In all of the studies except for Eth (F = 2.8, p = 0.1), the experimental intervention (deep talk or drug) significantly increased feelings of closeness with the conversation partner (ND Study: F = 8.4, p = 0.007; MDMA Study: F = 10.5, p = 0.007; and MA Study: F = 12.6, p = 0.003; Fig. 1A). In the MDMA study, the drug had a significantly greater effect on younger participants (drug x age interaction, F = 35.0, p = 0.0001).

Fig. 1.

Ratings of perceived interpersonal closeness (A), connectedness (B), perceived partner care (C), and conversation meaningfulness (D). Bars depict mean ratings ± SEM across four studies: (1) No drug study, small (White bar) vs. deep (Gray bar) talk condition; (2) MDMA study, placebo (White bar) vs. MDMA (Purple bar); (3) MA study, placebo (White bar) vs. MA (Green bar); (4) Eth study, placebo (White bar) vs. alcohol (Blue bar). Main effect of drug/talk condition: *p < 0.05, **p < 0.005, ***p < 0.0005.

Ratings of connectedness

The experimental condition for all studies (deep talk or drug) significantly increased feelings of partner connectedness (ND Study: F = 15.0, p = 0.0005; MDMA Study: F = 16.2, p = 0.002; MA Study: F = 8.6, p = 0.01; Eth study, F = 6.0, p = 0.02; Fig. 1B). In the MDMA study, the drug had a significantly greater effect on younger participants (drug x age interaction, F = 18.4, p = 0.002).

Perceptions of partner care

MDMA and MA led to greater feelings that their conversation partner cared about them compared to when they received placebo (MDMA: F = 17.3, p = 0.001; MA: F = 6.4, p = 0.02), an in the MDMA study, the drug had a significantly greater effect on younger participants (drug x age interaction, F = 8.6, p = 0.01). Alcohol did not alter these ratings (F = 2.2, p = 0.14). The Deep Talk condition increased ratings of partner care compared to Small Talk (F = 8.7, p = 0.006), and this effect was greater in older participants (drug x age interaction, F = 6.2, p = 0.02) (Fig. 1C).

Conversation meaningfulness

MDMA increased how meaningful the conversation was (F = 25.3, p = 0.0002), and these effects were more pronounced in younger participants and in men (drug x age x sex interaction, F = 7.2, p = 0.02). MA also increased meaningfulness of the conversation (F = 12.6, p = 0.003), but alcohol did not alter these ratings (F = 2.8, p = 0.11), compared to placebo. The Deep Talk intervention increased ratings of meaningfulness compared to Small Talk (F = 22.9, p < 0.0001) (Fig. 1D).

LIWC results

Table 2 shows the results of the LIWC analysis on a range of variables. The three drugs had minimal effects on speech contact: MDMA increased Positive Tone during the conversations, but decreased number of words per sentence, and MA decreased Prosocial content. In contrast, the Deep Talk intervention altered subjects’ speech in many ways compared to Small Talk, consistent with the differences in the topics assigned to the subjects during the conversations.

Table 2.

Comparison of word counts (mean ± SD) across word categories in non-drug, MDMA, MA, and eth studies.

LIWC Category	Non-drug			MDMA			Methamphetamine			Alcohol
	small	deep	sig	plc	MDMA	sig	plc	MA	sig	plc	Alc	sig
Words per Sentence	6.3 (1.4)	5.2 (0.8)	***	6.6 (0.9)	6.0 (1.0)	**	7.1 (1.2)	7.1 (1.2)	ns	8.8 (1.5)	8.9 (1.6)	ns
Authentic	94.9 (4.7)	84.5 (16.9)	**	90.9 (7.6)	92.2 (10.5)	ns	91.0 (15.2)	92.4 (6.3)	ns	84.0 (11.8)	83.7 (9.1)	ns
Positive Tone	4.3 (1.3)	4.6 (1.7)	ns	3.9 (1.1)	4.8 (1.6)	**	4.3 (1.1)	3.9 (1.5)	ns	3.4 (0.7)	3.5 (1.1)	ns
Negative Tone	1.4 (0.8)	2.3 (1.3)	**	0.9 (0.4)	0.8 (0.4)	ns	1.1 (0.6)	1.0 (0.5)	ns	0.6 (0.3)	0.5 (0.3)	ns
Emotion	1.9 (0.9)	3.2 (1.5)	***	1.8 (0.7)	2.1 (0.7)	ns	2.0 (0.8)	1.7 (0.6)	ns	1.4 (0.5)	1.4 (0.6)	ns
Positive Emotion	1.3 (0.8)	1.4 (0.7)	ns	1.3 (0.5)	1.6 (0.7)	ns	1.5 (0.7)	1.2 (0.5)	ns	1.0 (0.4)	1.1 (0.5)	ns
Negative Emotion	0.4 (0.3)	1.3 (1.0)	***	0.3 (0.3)	0.3 (0.3)	ns	0.4 (0.3)	0.3 (0.3)	ns	0.3 (0.2)	0.2 (0.2)	ns
Anxiety	0.1 (0.1)	0.2 (0.3)	*	0.0 (0.1)	0.1 (0.1)	ns	0.1 (0.1)	0.1 (0.2)	ns	0.1 (0.1)	0.1 (0.1)	ns
Anger	0.1 (0.2)	0.2 (0.3)	ns	0.1 (0.2)	0.1 (0.1)	ns	0.1 (0.1)	0.1 (0.1)	ns	0.1 (0.1)	0.1 (0.1)	ns
Sad	0.1 (0.2)	0.4 (0.5)	***	0.1 (0.1)	0.0 (0.1)	ns	0.0 (0.1)	0.1 (0.1)	ns	0.0 (0.1)	0.0 (0.0)	ns
Prosocial	0.3 (0.3)	0.8 (0.6)	**	0.2 (0.2)	0.3 (0.2)	ns	0.4 (0.3)	0.2 (0.2)	*	0.2 (0.1)	0.3 (0.2)	ns

p < 0.05*, p < 0.005**, p < 0.001***.

Discussion

These analyses show that MDMA, methamphetamine and alcohol increased feelings of connection or closeness during a conversation with a stranger. The feelings of connection were of a similar magnitude as those observed in a non-drug study, in which participants engaged in deep vs. small talk². The studies were highly controlled: Testing took place under laboratory conditions and participants were relatively homogeneous with regard to age, education, body weight, and other demographic characteristics; the drugs were administered using a within-subject, placebo-controlled double-blind design, using a standardized procedure and validated outcome measures including audio recordings. The observation that MDMA, methamphetamine and alcohol all increase feelings of social connection raises the possibility that these effects contribute to the drugs’ rewarding value in social settings.

The present findings extend other studies reporting pro-social effects of drugs, by examining the specific outcome measure of feeling connected with a partner. Other studies have shown that MDMA, methamphetamine and alcohol increase self-reports of feeling ‘sociable’, and increase reactivity to social cues^1,5,14–17. Sayette and colleagues¹⁸ studied the effects of alcohol administered in groups, showing that alcohol enhanced behaviors associated with positive affect (e.g., smiling) and increased self-reported bonding, concluding that alcohol facilitates bonding during group formation. Other studies show that participants report liking drugs more, and are more likely to choose to consume drugs, when they are in social settings^15,19,20. These findings are consistent with the idea that social contexts, and perhaps because of feelings of social connection induced by drugs, can enhance the drugs’ rewarding effects.

In the present analysis, MDMA and methamphetamine (and deep talk) increased participants’ self-reports of how meaningful they found the conversation and that they felt their partner cared about them, but alcohol did not produce these effects. Differences in responses across the drugs are difficult to compare because the data were obtained from separate studies, with separate samples. Moreover, it is extremely difficult to compare drugs with only a single dose of each drug, because of possible differences in dosing. Nevertheless, the single doses tested increased feelings of connectedness in all three studies, whereas MDMA and methamphetamine, but not alcohol, increased meaningfulness and partner caring. It is possible that different underlying neural mechanisms and behavioral processes underlie feelings of connection. Indeed, we previously reported³ that whereas both MDMA and methamphetamine increased feelings of connectedness, connectedness after MDMA was correlated with increases in oxytocin levels, whereas connectedness after methamphetamine was not. Thus, the construct of feeling connected with others may be multifactorial, and controlled by different processes.

In the present study we also examined the content of the conversations, using Linguistic Analysis and Word Count^9,13. With this analysis, the content of conversations in the Deep Talk condition differed on many variables from the Small Talk condition (Table 2), perhaps not surprisingly because different topics were provided. However, none of the drugs significantly affected speech content. The lack of difference in the drug studies make it unlikely that the increased feelings of connectedness were mediated by the drugs’ effects on the content of the conversations.

We note that the drugs reported here have numerous other behavioral and subjective effects, some of which are similar across drugs, and some different^21–24. Yet, all three drugs produced comparable feelings of connectedness, despite differences in other effects. An interesting question for future research will be to understand how the feelings of connection originate, and whether, or how, they are related to effects such as feelings of increased energy, sociability or drug liking, or to physiological measures such as oxytocin. Future studies investigating the effects of other drugs, such as opioids, cannabinoids or caffeine, on feelings of connection are needed to determine the specificity of this effect.

The analyses presented here have both strengths and limitations. The strengths include the rigorous experimental control over doses, participants, conversation methods and outcome measures, and the inclusion of a ‘positive control’ for increasing feelings of connectedness without a drug. Limitations include the lack of random assignment to drug conditions, and minor methodological differences between the studies. The study subjects differed in drug use history, number of sessions, and whether the partners were co-participants or confederates. The studies are also limited by the strict inclusion and exclusion criteria, raising question about whether similar effects would be detected in a more heterogeneous sample, including those with significant psychiatric symptoms, more extensive drug use histories, or different demographic characteristics. In the present analysis we found that younger participants reported stronger subjective responses to MDMA. However, interpretation of these findings are limited due to small sample sizes (N = 17). Future studies should examine the effect of age on feelings of MDMA-induced connection in a larger sample, and in a wider age range.

In conclusion, the present analysis illustrates a potentially important dimension of the effects of drugs in social settings, that is, their ability to increase feelings of connectedness. Although many drugs are used in social settings, most laboratory-based drug studies have tested participants’ responses to drugs under socially isolated conditions¹. There are many ways in which social environments could influence the effects of drugs, and the present analysis shows that increases in feeling socially connected may be one of these. This increase in feeling socially connected may add to the rewarding effects of drugs.

Author contributions

HdW: Conceptualization, Funding acquisition, Supervision, Writing; HM: Data curation; Formal analysis, Visualization, Writing; EH, TL and SS: Methodology; Project administration, Data curation, Investigation, Validation.All authors reviewed the manuscript.

Data availability

The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Competing interests

The authors declare no competing interests.

Disclosures

HdW is on the Board of Directors of PharmAla Biotech, and on scientific advisory committees of Gilgamesh Pharmaceuticals and MIND Foundation. These activities are unrelated to the present report. Other authors declare no conflicts.