Microdosing Round 2 | Djai Baaten & Nils Paar

Microdosing’s biggest promise—measurable cognitive gains beyond placebo—has come under pressure, even as participants report real improvements in mood and well-being. A citizen-science study published in eLife used “self-blinding” (participants took microdoses in opaque gel capsules inside envelopes marked with QR codes) and split volunteers into three groups: placebo-only, half placebo/half active, and active-only. Across psychological questionnaires and computerized cognitive tests, people improved on psychological measures, but the study found no statistically significant difference between microdosing and placebo groups in how much they improved.

That pattern has fueled headlines claiming microdosing is “no better than placebo,” but the discussion around the findings is more nuanced. The study’s design was considered methodologically solid, including a strong placebo response on self-reported outcomes and a lack of cognitive-test separation between groups. Still, several limitations complicate any final verdict: participants sourced their own substances (with most using LSD), meaning researchers couldn’t verify purity or dosing accuracy; volunteers self-selected into the study, likely bringing expectations that could amplify placebo effects; and the cognitive tests may have been too narrow to capture subtler, real-world changes people often describe.

One striking detail: participants correctly guessed whether they’d taken a microdose in about 72% of cases—well above chance. That suggests many people can detect something about their dosing day, even if that detection doesn’t translate into objective cognitive-test advantages. The researchers also emphasized that psychological benefits were present in the microdosing group, while cognitive benefits weren’t clearly distinguishable from placebo.

Beyond placebo, the conversation stresses that microdosing research remains sparse and mixed. Other studies cited in the discussion point to potential biological and clinical signals: a 2019 placebo-controlled study reported changes in functional brain connectivity that may relate to mood; a study reported increased brain-derived neurotrophic factor (BDNF), a marker associated with neuroplasticity; and a 2020 placebo-controlled pain study using LSD found microdosing effects comparable to standard opioid treatment in a cold-water pain paradigm (noted as small and needing replication). A separate 2020 placebo-controlled study reported both positive and negative cognitive effects, underscoring that outcomes may vary by measure and dose.

The second major topic was heart-valve risk, a concern tied to serotonin 2B (5-HT2B) receptor binding. Some drugs linked to valvular heart disease were withdrawn from markets, and the hypothesis is that psychedelics’ interaction with 5-HT2B could pose risk with repeated use. The discussion argues that microdosing protocols typically include breaks (e.g., not daily dosing, and often cycling on/off), which could reduce exposure compared with the withdrawn drugs that were taken daily over long periods. Even so, the speakers acknowledge there’s no conclusive evidence that microdosing is definitively safe for long-term heart outcomes, and there are no clear case reports establishing causation. The takeaway is a call for personal risk assessment—especially for people with family history—while waiting for better, more targeted studies.

Overall, the central message is a split reality: mood and well-being improvements appear robust, but objective cognitive advantages over placebo are not yet proven; meanwhile, safety questions—particularly cardiovascular—remain technically plausible but scientifically unresolved.