dcyphr | LSD Acutely Impairs Fear Recognition and Enhances Emotional Empathy and Sociality


Lysergic acid diethylamide (LSD) has well-known effects on perception and is used to supplement psychotherapy for anxiety in those with life-threatening illnesses. Unknown, however, is its effects on emotional processing in ways applicable to therapy. Using the Face Emotion Recognition Task (FERT) to measure emotional processing, the Multifaceted Empathy Test (MET) to measure empathy, and the Social Value Orientation (SVO) test to assess social behavior, the authors found LSD to impair fear recognition and enhance empathy and associating with others. 


LSD is associated with an increase in quality of life and a decrease in anxiety in those suffering from a terminal illness (i.e., advanced-stage cancer). Similar to LSD, psilocybin (“shrooms”) and MDMA (ecstasy) have been used for psychotherapy. LSD, psilocybin, and MDMA have been shown to produce similar effects of enhancing “good” traits like openness and optimism. It is worth noting that MDMA is not a hallucinogen like LSD and psilocybin. LSD has been shown to generate longer-lasting effects (i.e., openness) that are similar to MDMA. This may be related to its psychedelic properties and how it activates 5-HTA2 receptors. 


Data was pooled from two similar studies (double-blind, randomized, with placebos) in which 100 μg of LSD (or placebo) was given to 24 subjects and 200 μg of LSD (or placebo) was given to 16 subjects. Subjects took the LSD in a hospital room with an investigator who stayed with a subject for at least 12 hours after administration of the drug. Since responses to LSD typically peak around 2-3 hours after administration, its effects on emotional processing and prosociality were assessed around 5-7 hours after administration. 


Facial Emotional Recognition

LSD was shown to reduce recognition of fearful faces in both groups compared to placebo groups, with no significant differences in dosage. It had no significant effect on recognizing angry, happy, or neutral faces. 


LSD in both groups (100 μg and 200 μg) increased implicit and explicit empathy scores. This was only statistically significant in the 200 μg group. LSD decreased cognitive empathy (correctly identifying emotional responses). This was statistically significant in both groups. 

Social Value Orientation

LSD significantly increased prosocial behavior, which was statistically significant only when assessing the larger sample. 

Subjective Mood Effects

LSD increased feelings of prosociality and empathy (i.e., openness and feeling close to others) with a slight dose-dependent increase in fear and poor effects of LSD. Ratings of wellbeing and introversion also increased with LSD. 

Vital Signs and Adverse Effects

LSD increased blood pressure, pupil size, heart rate, and body temperature but did not produce any serious adverse effects. 

Plasma Drug Levels and Correlations Between Effects

Plasma levels were higher in the 200 μg dose group compared to the 100 μg group. Plasma LSD was associated with increases in trust and openness towards others, which was associated with increases in explicit emotional empathy scores for positive situations. 


LSD affects emotional processing by decreasing the recognition of negative facial expressions, which is similar to the effects of MDMA and psilocybin. Emotional empathy and prosociality were increased by LSD with dose-dependent effects on empathic mood (i.e., feeling close to others). The effects of LSD may be relevant to facilitating patient-therapist interaction and have other potential psychotherapeutic benefits. LSD was well tolerated with minor adverse effects such as fatigue lasting up to 72 hours. 


The dose effects were assessed using different subjects instead of within-subject. Emotional recognition was examined using artificial pictures (rather than real people) and physiological emotional responses (i.e., face muscle responses) were not investigated. Whether LSD had an effect on participants feeling cared for by others (empathy directed to themselves rather than others) should be investigated.