Table 2. Psychedelic Therapy and Suicidality^a.

study	year	design	intervention	suicidality assessment	suicidality outcome	study quality
Randomized Controlled Trials
Davis, Barrett et al.24	2020	N = 24; individuals with major depressive disorder; wait-list controlled crossover study	psilocybin-assisted psychotherapy (two doses)	clinician-assessed suicidal ideation (CSSRS-SII)	Compared with wait list, non-significant decreases in suicidal ideation occurred over time. Post-crossover, large and significant decreases in suicidal ideation occurred (η2 = 0.44, 90% CI 0.24–0.56, p < 0.001).	2
Gasser et al.81	2015	N = 12; anxiety associated with a life-threatening illness	LSD-assisted psychotherapy (two doses)	semistructured interview (12-month follow-up)	Among participants, 33% individuals reported improved symptoms including “...better sleep, no more suicidal thoughts, less depressed feelings”.	2
Zeifman et al.35	2019	N = 29; individuals with treatment-resistant depression (n = 14 received active treatment); randomized placebo-controlled trial	ayahuasca (single dose) administered in a psychiatric unit	clinician-assessed suicidality (MADRS-SI [BL, 1, 2, and 7 days])	Compared with placebo, ayahuasca was not associated with significant reductions in suicidality (p = 0.088). Moderate between-group effect sizes were observed at 1 day (d = 0.58, 95% CI −1.32–0.17), 2 days (d = 0.56, 95% CI −1.30–0.18), and 7 days (d = 0.67, 95% CI −1.42–0.08) after ayahuasca. Large within-group effect sizes were observed at 1 day (d = 1.33, 95% CI 1.25–3.18), 2 days (d = 1.42, 95% CI 1.50–3.74), and 7 days (d = 1.19, 95% CI 1.21–3.50) after ayahuasca. At 7 days after ayahuasca, there was a strong, but non-significant, association between reductions in suicidality and non-suicide-related depressive symptoms (r = 0.53, p = 0.053).	2
Open-Label Trials
Anderson et al.82	2020	N = 18; gay-identified, cis-gender men, 50 years or older living with HIV	psilocybin-assisted group psychotherapy	clinician-assessed suicidal ideation (CSSRS-SII)	No significant decreases in suicidal ideation occurred over time, with a medium effect size (ηp2 = 0.12). At 1 day post-psilocybin, remission of suicidal ideation occurred (mean suicidal ideation = 0) across participants (mean reduction = −0.5).	3
Carhart-Harris, Bolstridge et al.23	2018	N = 19; treatment-resistant depression	psilocybin (two doses) with psychological support	self-reported suicidality (QIDS-SI [BL and 1, 2, 3, 5, 18, and 36 weeks]; clinician-assessed suicidality (HAM-D-SI [BL and 1 week)]	The authors note a reduction in QIDS-SI 1 week (mean reduction = −0.90, 95% CI −0.4 to −1.4, p < 0.002) and 2 weeks (mean reduction = −0.85, 95% CI −0.4 to −1.3, p < 0.004) post-treatment; decreases at 3 weeks (mean reduction = −0.80, 95% CI −0.25 to −1.3, p = 0.01) and 5 weeks (mean reduction = −0.70, 95% CI −0.22 to −1.2, p = 0.01) post-treatment were not significant after Bonferroni correction. QIDS-SI at 18 and 36 weeks not reported. A reduction in HAM-D-SI (mean reduction = −0.58, 95% CI −0.58 to −1.3, p < 0.001) and 16 of 19 with HAMD-SI = 0 occurred at 1 week post-treatment.	3
Osório et al.83	2015	N = 6; individuals with recurrent major depressive disorder. Participants were included in Zeifman, Singhal et al.36	ayahuasca (single dose) administered in a psychiatric unit	clinician-assessed suicidality (MADRS-SI and HAM-D-SI [BL, 40, 80, 140, and 180 min, 1, 7 14, and 21 days])	For the MADRS, the authors reported that “...the greatest score changes were observed for items related to depressed mood, feelings of guilt, suicidal ideation...”. For the HAM-D, the authors reported that “...the most significant score changes were observed for items related to apparent and expressed sadness, pessimistic thinking, suicidal ideation, and difficulty concentrating...”. Statistical tests for suicidality not reported.	3
Zeifman, Singhal et al.36	2020	N = 17; recurrent major depressive disorder (n = 15 with suicidality at BL were included in analyses)	ayahuasca (single dose) administered in a psychiatric unit	clinician-assessed suicidality (MADRS-SI [BL and 40, 80, 140, and 180 min, and 1, 7, 14, and 21 days])	Significant acute decreases in suicidality (p = 0.002) occurred, including decreases 40 minutes (Hedges’ g = 0.65, 95% CI 0.28–1.73, p < 0.05), 80 minutes (g = 0.89, 95% CI 0.53–2.14, p < 0.01), 140 minutes (g = 0.94, 95% CI 0.62–2.05, p < 0.001), and 180 minutes (g = 1.31, 95% CI 0.98–2.35, p < 0.001) after ayahuasca. Significant postacute decreases in suicidality (p < 0.001) occurred, including decreases 1 day (g = 1.62, 95% CI 1.28–2.45, p < 0.001), 7 days (g = 1.57, 95% CI 1.09–2.65, p < 0.001), 14 days (g = 1.53, 95% CI 1.21–2.52, p < 0.001), and 21 days (g = 1.75, 95% CI 1.36–2.78, p < 0.001) after ayahuasca. Among the two individuals with no suicidality at BL, one had a score of MADRS-SI = 1 at 1 day post-ayahuasca and returned to MADRS-SI = 0 at all other time points. The other individual showed no elevation in suicidality. Acute (40 min) and postacute (21 days) reductions in suicidality were associated with reductions in nonsuicide related depressive symptoms (r = 0.69, p = 0.005 and r = 0.52, p = 0.049).	3
Case-Reports, Case Series, and Survey Studies
Baker34	1964	N = 150; patients with “non-functional psychiatric disorders”	LSD therapy (1–10 sessions)	descriptive	One completed suicide and one sudden death of unknown cause (both weeks after LSD administration) occurred. The authors reported that “suicidal... risk has not been increased... This experience is not out of line with ordinary suicide risk in a comparable group of patients not subjected to this form of treatment.” The authors reported at least nine serious suicide attempts within this patient group prior to LSD therapy	4
Chandler and Hartman84	1960	N = 110; psychiatric patients	LSD therapy (1–26 doses per patient; mean = 6.2)	descriptive	One suicide occurred following LSD therapy in a previously suicidal patient	4
Cohen85	1960	N = 44; survey of clinicians providing LSD and mescaline therapy to “almost five thousand individuals... on more than 25,000 occasions”	LSD and mescaline therapy (1–80 doses)	descriptive	The authors described post-LSD therapy suicidal behavior not reported elsewhere in the present review: one completed suicide, two suicide attempts, and one instance of wrist slashing with a razor blade (not identified as a suicide attempt). The authors reported that “In only a very few instances a direct connection between the LSD experience and the movement toward self-destruction could be discerned...” and that “...all suicidal acts have been in disturbed patients rather than normal subjects.” Among individuals that received psychedelic therapy, estimated rates were attempted suicide = 1.2/1000 and completed suicide = 0.4/1000, and in “experimental subjects”, the rate was 0/1000 for both attempted and completed suicides.	4
Cohen and Ditman86	1963	N = 5; individuals with a range of clinical presentations	LSD therapy (8 doses)	descriptive	One female was included with challenging and “chaotic” early life experiences; prior to LSD therapy, she had made a suicide attempt. At 2 years following LSD therapy, she was “...obsessed about going crazy or killing herself...”. She attempted suicide with barbiturates some time after the LSD therapy.	4
Denson87	1969	N = 237; individuals with a range of clinical presentations (primarily inpatients)	LSD therapy (1–11 doses; mean doses = 1.74); 411 total number of treatment sessions	descriptive	The authors reported two completed suicides and one suicide attempt in individuals that had received LSD therapy (1 and 5 years after LSD therapy). The authors described one suicide attempt (2 days after LSD therapy) and one instance of “...short-lived paranoid state with suicidal impulses...” immediately following LSD therapy and 3 months later. They also indicated that four individuals were “...considered to be in danger of injuring himself or committing suicide...”.	4
Eisner and Cohen88	1958	N = 2; review; describes suicide-related outcomes not reported elsewhere	experimental administration of LSD	descriptive	On the basis of personal communication, the authors reported two completed suicides. They also reported that “Personal contact with therapists using LSD-25 have turned up other cases of suicidal preoccupation and of actual suicide...” and “We are inclined to believe... that the possibility of suicide may be a real hazard, as it is in the treatment of any serious mental illness. From our experience... this danger appears to be restricted to the higher dosage level–those above 75 gamma–and an unfamiliarity with the drug.”	4
Fink et al.89	1966	N = 65; treatment-resistant patients with psychosis receiving in-patient care	LSD therapy (1–15 doses)	descriptive	One suicide attempt occurred 3 days after LSD therapy. The author noted that 2% of patients who received repeated LSD therapy had “prolonged adverse reactions” and that the risks of these “prolonged psychoses” associated with LSD abuse, including “suicidal preoccupations”, are greater in “...subjects with emotional lability and psychopathic features rather than in those with more classical forms of schizophrenia...”.	4
Geert-Jörgensen et al.90	1964	N = 157; individuals with a range of psychiatric disorders	LSD therapy (5–58 doses)	descriptive	One completed suicide (6 months after treatment) was reported, unrelated to LSD therapy. Four suicide attempts (one deemed serious and three deemed not serious) in the days after LSD therapy. The authors reported that these suicide attempts “...did not occur at times when the patients had been in states attributable to the LSD-after-effects repercussions...”.	4
Knudsen91	1964	N = 1; female patient; results described in Smart and Bateman65,b	LSD therapy (5 doses)	descriptive	suicidal ideation and one suicide attempt	4
Kristensen92	1962	N = 23; individuals with a range of clinical presentations	LSD therapy (large doses of LSD)	descriptive	A male patient with “severe character neurosis” completed suicide (1 h after LSD administration).	4
Malleson93	1971	N = 4470 (n = 4300, patients in the United Kingdom administered LSD 49,000 times in a clinical context; n = 170, experimental subjects administered LSD 450 times); survey of doctors (N = 73) administered LSD to humans	LSD administered in a clinical or experimental research context	descriptive	Among those administered LSD in a clinical context, there were three completed suicides that “...appeared to have a temporal relationship to LSD”. Nine cases of serious suicide attempt also occurred, as did eleven potential suicide attempts where “...the data are insufficient to categorize them.” Suicide rate of 0.0007%. No completed or attempted suicides reported among experimental subjects.	4
Martin94	1964	N = 1; adult with delusions of persecution, hallucinations, ideas of reference, occupational impairment and “suicidal feelings”	LSD therapy (12 doses)	descriptive	The authors reported that the patient gained “...insight into the meaning of his symptoms, leading to a resolution of his conflicts. One year later his stability had not relapsed.”	4
Sandison and Whitelaw95	1957	N = 94; individuals with varying psychiatric disorders	LSD therapy	descriptive	One suicide attempt by strangulation and three individuals who wished to suicide by drowning occurred during the acute phase of the LSD experience. “Patients in this condition can usually be persuaded to take pentobarbitone, after which the suicidal tendencies subside and are not necessarily present between treatments.” The authors reported that “In our experience, marked suicidal urges have particularly occurred during the treatment of anxiety neurosis, and are not necessarily confined to patients who had depressive or suicidal ideas before treatment was commenced... among the risks of treatment, the emphasis should be shifted to the possibility of suicide.”	4
Savage96	1957	N = 6; inpatients	LSD therapy (weekly)	descriptive	One female inpatient with schizophrenia and chronic somatic illusions of being dead completed suicide (by throwing herself under a train) while on a visit home.	4
Savage et al.97	1964	N = 113; individuals with a range of clinical presentations	LSD or mescaline therapy (1 dose)	descriptive	One suicide attempt occurred 2 months after LSD therapy (individual with history of depression, suicidal attempts, and hospitalization).	4
Van Ree98	1969	N = 1; severely suicidal patient	LSD therapy	descriptive	Clinical improvements were reported in a “patient with suicidal tendencies which had been present in a very severe form for many years”.	4

^aBL = baseline. CSSRS-SII = Columbia-Suicide Severity Rating Scale-Suicidal Ideation Intensity.⁹⁹ HAM-D-SI = Hamilton Depression Rating Scale-Suicidality Item.¹⁰⁰ LSD = Lysergic acid diethylamide. MADRS-SI = Montgomery–Åsberg Depression Rating Scale-Suicidality Item.¹⁰¹ QIDS-SI = Quick Inventory of Depressive Symptomatology-Suicidality Item.⁸⁰

^bFull-text not available.