A Systematic Review of the Effects of Psychedelics on Multiple Facets of Intimacy

Anna Bradford

Ethan Freedman

Rachel Dinero

Department of Psychology, University of California, Los Angeles

Department of Psychological and Brain Sciences, Colgate University

Department of Psychology, Le Moyne College

Abstract

In recent years, the potential psychological benefits of psychedelic drugs has garnered increasing interest from academic and medical communities. We conducted a systematic review of literature examining the effects of psychedelic drugs on multiple facets of intimacy (i.e., closeness developed through verbal or non-verbal communication within the context of interpersonal relationships). The initial search yielded 5,902 studies, of which 19 met the inclusion criteria. Across these studies we identified four facets of intimacy: emotional intimacy, attachment, social anxiety, and emotional intimacy in sexual contexts. Impact on these domains can be negative (e.g. disconnectedness) or positive (e.g. compassion, love, and decreased social anxiety). As such, the existing literature suggests that psychedelic drugs have the potential to promote intimacy in certain contexts. However, further research is needed to establish the extent of these benefits and the contexts within which they occur.

   Keywords: psychedelics, intimacy, therapy, intimate relationships, interpersonal relationships

A Systematic Review of the Effects of Psychedelics on Intimacy

The goal of the present research was to conduct a systematic review of literature on the positive and negative impacts of the psychedelic drug use on intimacy in interpersonal relationships. There is a developing literature on the benefits of psychedelics, particularly within therapeutic contexts, for the treatment of anxiety, depression, and PTSD (Schuitmaker, 2023; Timmerman et al., 2022; Yaden et al., 2021). As the potential benefits of small doses of psychedelics in therapeutic contexts are being explored, there is emerging research considering how psychedelic use may impact relationship wellness and intimacy (e.g., Monson, 2020; Watts et al., 2022). Psychedelics drugs [i.e., psilocybin, methylenedioxymethamphetamine (MDMA), dimethyltryptamine (DMT), 5-MeO-DMT, ayahuasca, mescaline, lysergic acid (LSD), ketamine, and ibogaine] are a subclass of hallucinogenic drugs that induce altered states of consciousness (Yaden et al, 2021). Use of these drugs has been associated with positive intimacy-related outcomes.  For instance, MDMA has been linked to higher patient and partner-rated relationship adjustment for individuals with post-traumatic stress disorder (PTSD) when used as a part of cognitive behavioral conjoint therapy (Monson, 2020). Additionally, in a therapeutic setting, psilocybin was found to be more effective than escitalopram, an antidepressant, in increasing feelings of connectedness (Watts et al., 2022). Negative effects of psychedelic use have also been observed, including existential struggle, social disconnection, depersonalization, and derealization. Although, taking psychedelics in guided settings may mitigate these negative effects (Evans et al., 2023).

Given these mixed findings, the use of psychedelic drugs in therapeutic settings remains stigmatized and controversial (Velmans, & Schneider, 2007). The United States Food and Drug Administration (FDA) has approved ketamine for use as an anesthetic, but has explicitly indicated that this drug is not approved for psychiatric uses (U.S. Food & Drug Administration, 2023). Esketamine (a substance derived from ketamine) for depression that is resistant to other treatments (U.S. Food & Drug Administration, 2019). The FDA has granted psilocybin and MDMA breakthrough therapy status, which helps expedite research on the effectiveness of these drugs for the treatment of depression and PTSD respectively (Heal, et al., 2023). However, in August, 2024, the FDA rejected an application to approve MDMA for the treatment of PTSD, citing a need for more research (Lykos Therapeutics, 2024). Additionally, these applications have focused exclusively on depression and PTSD, rather than looking at the potential impact of psychedelics on intimacy-related outcomes. As such, the goal of the present research was to identify all existing research that assessed psychedelic use and its potential negative or positive impact on intimacy. For this systematic review, we included research in which psychedelic drugs were used in therapeutic, recreational, or clinical settings. Intimacy was operationally defined as closeness developed through verbal or non-verbal communication within the context of interpersonal relationships (Perlman & Fehr, 1987).

Methods

The present research is a systematic review investigating psychedelics and the extent to which they impact intimate interpersonal relationships and was conducted following the Prepared Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and pre-registered through Open Science Framework (OSF) at https://osf.io/dv96g.

Inclusion Criteria

The inclusion and exclusion criteria for study selection were defined prior to review and were as follows: 1) must investigate psychedelics and the extent to which they impact intimate relationships with others, 2) must be peer reviewed/published, 3) must be available in English, 4) must investigate psychedelics as a tool for therapy, recreation, developing agency, awareness, and or consciousness on topics related to intimacy, 5) must investigate psychedelic drugs including, but not limited to, psilocybin, MDMA, DMT, 5 - MeO- DMT, ayahuasca, mescaline, LSD, ketamine, and ibogaine, 6) must investigate intimacy, defined as closeness developed through verbal or non-verbal communication within the context of interpersonal relationships, 7) must not be a systematic review or meta-analysis (note: any systematic reviews or meta-analyses that met other inclusion criteria were reviewed to ensure that all included studies were identified in our our search).

Search Strategy

Electronic databases and search terms were established prior to conducting the systematic review (Table 1). We ran 125 combined search terms where each psychedelic drug from the defined list was paired with each possible treatment setting and outcome once via seven databases. We also included “altered states of consciousness” in the psychedelic drug search term category to identify any studies involving psychedelic drugs that did not specify drug type (Velmans, & Schneider, 2007). Any search term that resulted in more than 100 items was considered too broad and these searches were not used. The search process was conducted between February 12, 2023 to April 1, 2023. All items identified in these searches were evaluated independently by the first and second author. Any inconsistencies in inclusion/exclusion between the first and second author were evaluated by the third author and discussed as a group until consensus was reached.

Results

Our initial search yielded 5,902 potential studies to be screened for inclusion. Of these, 3,495 were identified as duplicates, resulting in  2,407 abstracts to evaluate for inclusion. Based on an abstract review, we excluded 2364 studies, which resulted in 43 full texts to evaluate. Full-text evaluation resulted in an additional 24 studies being excluded, yielding a total of 19 studies assessing the impact of psychedelics on intimacy (Figure 1). From each of these studies we extracted participant demographics, study methodology, type of psychedelic drug being administered (and dosage if applicable), and any findings relevant to intimacy (Table 2). All search results and inclusion/exclusion are available through OSF at https://osf.io/shr5t/?view_only=c2ffe20075c84316a22d4fab5040fad1.

Assessing Study Methodology

There were numerous methodologies used in the reviewed studies, with some having multiple methodological components. As a result of the wide range of methods and measures used in the studies, categories outlined below are not mutually exclusive. (Note: superscript numbers correspond to studies listed in Table 2.) Experimental models were used for data collection in nine studies1, 2, 3, 6, 8, 13, 15, 16, 17, while non-experimental models for data collection were in the other ten4, 5, 7, 9, 10, 11, 12, 14, 18, 19. Only Kettner et al. (2021) and Watts et al. (2022) explicitly defined their methodology as observational9, 17. All studies involved some form of self-report data collection, either as a questionnaire, interview, or both. Four studies relied exclusively on interviews5, 7, 12, 14, four studies relied exclusively on questionnaires9, 15, 18, 19, and 11 studies relied on both questionnaires and interviews as part of their data collection1, 2, 3, 4, 6, 8, 10, 11, 13, 16, 17.

Drug administration varied across studies. Eight studies included participants who reported data on their experiences with drugs in an uncontrolled setting5, 7, 9, 10, 12, 14, 18, 19. Nine studies consisted of participants who consumed drugs in a controlled setting1, 2, 3, 6, 8, 13, 15, 16, 17. Cavnar (2014) studied participants in both an uncontrolled and controlled setting4. All studies included at least one of the following drugs: MDMA, dimethyltryptamine (DMT), 5 - MeO- DMT, ayahuasca, mescaline, lysergic acid (LSD), ketamine, or ibogaine. Psilocybin was investigated in seven studies 7, 9, 11, 14, 15, 17, 19, MDMA was investigated in ten studies ,1, 2, 3, 5, 6, 7, 8, 10, 12, 13, 16, 19, LSD was investigated in four studies ,7, 9, 14, 19 ayahuasca was explored in three studies4, 7, 9, ketamine was investigated two studies7, 9, DMT was investigated in two studies7, 9, 5-meO-DMT was investigated in one study9, mescaline was investigated in one study7, and ibogaine was investigated in one study9. Evans et al., (2023) and Kettner et al. (2015) addressed psychedelics that were not included in our initial list of defined psychedelics: salvia divinorum7 and peyote9. Lastly, we identified three contexts for drug consumption: therapeutic, recreational, and clinical. Lutkajtis & Evans (2022)11 investigated psychedelics a therapeutic context, recreational contexts were explored in ten studies4, 5, 7, 8, 9, 10, 12, 14, 18, 19, and clinical studies were observed in eight1, 2, 3, 6, 13, 15, 16, 17.

Assessing Intimacy Themes

We categorized intimacy-related assessments into four facets: emotional intimacy, attachment, social anxiety, and emotional intimacy in sexual contexts. Research assessing each facet is discussed below.

Emotional Intimacy. The emotional intimacy facet included measures of connectedness, love, empathy, compassion, and closeness. Emotional intimacy was measured via questionnaires, surveys, and interviews. This theme was the most prevalent among the studies, with 14 studies providing data related to at least one of the aforementioned terms1, 2, 3, 4, 5, 7, 9, 11, 12, 13, 10,  16, 17, 19. Evans et al., (2023)7 and Lutkajtis and Evans (2022)11 identified negative effects on feelings of connectedness following psychedelic usage, while nine studies identified only positive effects1, 2, 4, 5, 9, 10, 13, 16, 17. Three studies identified both positive and neutral effects on connectedness following psychedelic usage3, 12, 19. Three studies found positive effects of psychedelics on feelings of connectedness4, 9, 17. Studies assessing connectedness specifically referenced the drugs psilocybin, ayahuasca, LSD, ibogaine, 5-MeO-DMT, and DMT. Cavnar (2014)4 and Kettner et al. (2021)9 observed positive effects on connectedness when participants whose psychedelic experiences occurred in group settings, specifically spiritual ceremonies. Two studies reported negative impacts on feelings of connectedness. Evans et al. (2023)7 surveyed only individuals who have had negative experiences following a psychedelic experience, with 13% of participants reporting feelings of disconnect from others/society (Lutkajtis and Evans, 2022).11 interviewed nine individuals following a psychedelic retreat, two of whom reported feelings of disconnection from the retreat community.

There were two studies that assessed love. Wardle & Wit (2014)16 found that individuals who consumed MDMA self-reported greater feelings of love. Additionally, higher doses of MDMA were associated with increased love. Zeifman et al. (2023)19 found that psilocybin and MDMA taken in tandem result in feelings of love, while psilocybin used independently did not result in significant changes in f love. Three studies addressed empathy, all of which investigated MDMA exclusively. Borissova et al. (2021)3 reported that MDMA did not significantly affect feelings of self-reported empathy, while Baggott et al. (2015)1 found that MDMA increased self-reported empathy. Kostick and Schensul (2018)10 reported that individuals are motivated to consume MDMA to aid in the facilitation of empathy, yet did not include an experimental design that could assess changes in empathy. Two studies assessed closeness3,12, both investigating closeness in the context of MDMA use. Both Borissova et al. (2021)3 and McElrath (2005)12 found that MDMA increased subjective feelings of closeness to others. Only Zeifman et al. (2023)19 referenced compassion, finding that the combined use of a low dose of MDMA and psilocybin or LSD resulted in increased self-compassion but not other-directed compassion.

Attachment. The attachment facet was assessed in two studies14,15. Both studies included assessments of attachment anxiety and avoidance. Attachment anxiety is the extent to which individuals are hypersensitive to emotional cues and fear abandonment (Gillath et al., 2016). Avoidance is the extent to which individuals are dismissive of emotional cues and uncomfortable with closeness (Gillath et al., 2016). Stauffer et al. (2021)15 assessed changes in attachment anxiety and avoidance before and after administering psilocybin  treatments to male long-term AIDS survivors experiencing demoralization. There was a significant reduction in attachment anxiety at three months post-intervention with no change in attachment avoidance. Kamboj et al. (2015)8 found that participants with avoidant attachment styles reported greater challenges during the psilocybin experience, while Ryan, Copello, & Fox (2023)14 found that psychedelic drug users with avoidant attachment styles were more likely to feel greater increases in compassion from MDMA on states of compassion.

Social Anxiety. There were four studies2, 6, 7, 14 that investigated the impact of psychedelics on social anxiety.  Ryan, Copello, & Fox (2023)14 interviewed individuals that microdosed either psilocybin and LSD and found that users reported improved relationships and lower levels of social anxiety. Baggott et al. (2015)2 found that MDMA use decreased participant's concern about negative evaluation from others, which in turn helped facilitate emotional disclosure. Danforth et al. (2018)6 found that adults diagnosed with Autism Spectrum Disorder who consumed MDMA in a psychotherapeutic context experienced significantly lower levels of social anxiety, which, in turn, resulted in individuals reporting improved social interactions with romantic partners and family members. Some participants even reported being able to initiate dating for the first time in their lives. Alternatively, Evans et al. (2023)7 surveyed participants who had negative experiences with psychedelics and a minority indicated they had experienced social anxiety following a psychedelic experience.

Emotional Intimacy in Sexual Contexts. There were three studies10, 12, 18 that assessed emotional intimacy in sexual contexts. This facet captures emotional bonding that occurs during sexual activity. While we excluded any study from our systematic review that assessed sexual pleasure, we included research that focused on emotional intimacy that occurred during sexual activity. Kostick and Schensul (2018)10 surveyed participants who used MDMA during sexual activity and found that while the primary motivation for using MDMA was physical sexual pleasure, there was also motivation for MDMA usage that included relationship enhancement via sexual satisfaction and empathy. Additionally, MDMA usage during sexual behavior was associated with relationship insecurity, distress, dissatisfaction, and lack of mutual trust. CITE18 investigated men who have sex with men and used ketamine as a facilitator for sexual activities. Participants reported negative impacts from this behavior on intimate relationships as well as relationships with friends and family.

Discussion

The goal of this systematic review was to identify all published literature investigating the effects of psychedelics on intimacy. We created five facets of intimacy (i.e., emotional intimacy, attachment, social anxiety, and emotional intimacy in sexual contexts) and qualitatively assessed literature on each facet. Overall, there were predominantly positive impacts of psychedelics on emotional intimacy, attachment and social anxiety. There were noted negative effects of psychedelics for emotional intimacy,  feelings of connectedness, and individuals with avoidant attachment styles. Additionally, there were no reported positive effects of psychedelics on emotional intimacy in sexual contexts.

This systematic review also highlights the depth of literature in this field. There were only 19 studies that met our search criteria. Of these, only eight identified as experimental/clinical studies. The remaining 11 studies investigated recreational or non-clinical settings. While recreational usage studies provide important preliminary evidence of the impact of psychedelics, there are many limitations of these types of studies. Experimental trials with placebo groups and/or pre/post-intervention designs are critical to establishing causal effects of psychedelics. Additionally, recreational settings do not allow for precise data on dosage and timing, and self-reports are retrospective. Six of the 11 non-clinical studies relied exclusively on self-report data, while five were observational. Although self-report data is critical to assessing subjective experience, they can be biased in a variety of ways (e.g., social desirability) and may be particularly unreliable under the influence of consciousness-altering drugs (Rosenman et al., 2011). Finally, we note the relatively small sample sizes in many of the studies. Given the importance of empirical research in establishing the safety and effectiveness of any drugs, the field would benefit from more research, and more funding sources to support larger scale, high quality studies.

Limitations

One limitation of this systematic review is that we only included peer-reviewed published research. While this decision was made to ensure the quality of research, it also means that our findings are subject to publication bias. Data with small sample sizes, null findings, or even unpopular topics are less likely to be published (Joober, et al., 2012), and therefore would not be included in our review. Additionally, database searches yielding over 100 studies were excluded from the present research to ensure feasibility in executing the systematic review within a realistic timeframe. This could have led to relevant studies being missed in our search.

Conclusion

This systematic review has made it evident that future research should consider developing studies with both larger participant pools as well as experimental models for data collection. Such methods could provide more definitive evidence of psychedelics’ influences on an individual’s experiences with intimacy. Due to the nature of the discourse surrounding psychedelics, it’s necessarily challenging to receive approval for administering these substances even in a research setting. Despite this challenge, psychedelic usage has progressively become less stigmatized over time, and institutions are becoming more accepting of the literature that supports the psychological benefits of these drugs.

The present review demonstrates that psychedelic drugs can have both positive and negative effects on intimacy. The majority of research reviewed indicated that psychedelic drugs were associated with increased emotional intimacy, decreased attachment anxiety, and decreased social anxiety. Some studies, however, find evidence for no change or even decreased emotional intimacy. Further, the use of psychedelics in a sexual context, while motivated by the desire to increase emotional intimacy, do not lead to increased emotional intimacy and are, rather, associated with relational insecurity. While positive outcomes are far more represented in the literature, future research would benefit from developing studies using robust study designs including both larger participant pools as well as experimental models for data collection. As these studies cannot be conducted without adequate funding, we also encourage funding support to further our understanding of the potential costs and benefits of psychedelics. Whether maladaptive, beneficial, or neutral, understanding the role psychedelics play in mitigating, constructing, and deconstructing relationship dynamics is instrumental in progressing research on psychedelics in a therapeutic, clinical, and recreational context.

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Table 1

Electronic Databases and Search Term Combinations

Table 2

Extracted Content from Studies Meeting Inclusion Criteria

Figure  1

Search Summary