Anne Eckert

Preclinical studies suggest that lysergic acid diethylamide (LSD) may induce lasting changes in brain function and learning ability, but evidence in humans is uncertain. Motor learning, in particular, has clinical relevance but has not been investigated in human studies of psychedelics. Forty-five healthy subjects (24 women) participated in this randomized crossover trial comparing 100 µg LSD with a placebo. For up to one week after dosing, we investigated LSD’s post-acute neurophysiological effects using auditory tetanization with electroencephalography (EEG), paired associative stimulation (PAS) with transcranial magnetic stimulation (TMS), peripheral levels of brain-derived neurotrophic factor (BDNF). Additionally, online and offline motor learning were assessed one day after dosing with a sequence typing task. Questionnaires assessed perceived stress and cognitive flexibility one week after dosing. We found that offline motor learning significantly improved the day after LSD. One week after LSD, perceived stress was reduced and aspects of cognitive flexibility were increased. EEG data showed that LSD acutely decreased amplitudes of N1 and P2 auditory event-related potentials and still modulated P2 one week later. Motor-evoked potentials measured with TMS showed increased amplitude and faster latency under LSD. LSD did not alter BDNF levels. Our findings encourage future studies on LSD and learning and additionally highlight important challenges in the measurement of long-term potentiation in humans. The observed acute and lasting changes in neural signals provide insight into LSD’s effects on the auditory and motor systems.

Tauopathies are a group of neurodegenerative diseases characterized by the accumulation of abnormal tau protein, leading to mitochondrial dysfunction. Because of neurons’ high energy demands, such impairments significantly contribute to neuronal vulnerability. Recent evidence indicates that mitochondria can be transferred between cells to support energy-deficient cells through intercellular mitochondrial transfer (IMT). Given the impact of pathological tau on mitochondrial transport and cytoskeletal dynamics, we hypothesized that IMT is altered in tauopathies. We investigated IMT from astrocytes to neurons, as well as the influence of abnormal tau protein on this process, using co-cultures of SH-SY5Y cells (neuronal model) and A172 cells (astrocytic model). Key data were then confirmed in human iPSC-derived neurons and astrocytes. We show that IMT is enhanced in the presence of abnormal tau and occurs predominantly through contact-dependent mechanisms. Transferred mitochondria were either integrated into the host mitochondrial network, degraded in lysosomes, or remained isolated in the recipient cells’ cytosol. This transfer improved cellular respiration and was associated with increased bioenergetics in pathological cells. Together, our results highlight IMT as a link between tau pathology and neuronal metabolic adaptation, suggesting that this process reflects an endogenous metabolic adaptation holding therapeutic potential to mitigate energy deficits in neurodegenerative diseases.

Stress-related psychiatric disorders are frequently associated with impaired mitochondrial function, altered neuronal energy metabolism, and reduced neuroplasticity. Intracellular pathways such as PI3K/Akt and mTOR play central roles in regulating mitochondrial bioenergetics and neuronal structural adaptation. Gelsemium is traditionally used in integrative and homeopathic practice; however, the cellular effects of prolonged exposure to high serial dilutions remain insufficiently characterized. This study aimed to examine the effects of chronic exposure to Gelsemium preparations on mitochondrial function and neuronal plasticity in vitro. Human SH-SY5Y neuroblastoma cells were treated for 14 days with different Gelsemium preparations 9C, 15C, 30C. Mitochondrial bioenergetics, reactive oxygen species (ROS) production, cell viability, neurite outgrowth, and phosphorylation of Akt and mTOR were assessed using complementary biochemical, imaging, and signaling analyses. Chronic exposure to Gelsemium preparations was associated with increased ATP production, increased mitochondrial respiration and glycolytic activity, reduced oxidative stress, improved cell viability, and increased neurite outgrowth compared with untreated controls. These changes were accompanied by increased phosphorylation of Akt and mTOR. The convergence of bioenergetic, redox, morphological, and signaling readouts suggests a coordinated cellular response under prolonged exposure conditions. These findings indicate that chronic exposure to Gelsemium preparations (9C, 15C, 30C) is associated with coordinated changes in mitochondrial bioenergetics, redox balance, and Akt/mTOR signaling in neuronal cells under in vitro conditions.

3,4-Methylenedioxymethamphetamine (MDMA)-assisted psychotherapy (MDMA-AT) is being investigated as a treatment for several psychiatric disorders, particularly posttraumatic stress disorder. Phase 2 and 3 trials typically administered a first dose of MDMA followed by a second “booster” dose 1.5–2.5 h later, to extend the acute effect duration. However, the risks and benefits of the booster dose have not been systematically investigated. In this double-blind, randomized, placebo-controlled, cross-over study, we compared 120 mg MDMA followed by a 60 mg booster dose or placebo after 2 h, and placebo followed by placebo. The primary outcome was the overall duration of any subjective drug effects, measured by a Visual Analog Scale. Secondary outcomes included additional subjective effects, adverse effects, vital signs, and plasma concentrations of MDMA, oxytocin, and neurophysin I. Twenty-five healthy volunteers were included, and twenty-three (12 male, 11 female) completed all dosing sessions. The booster dose of MDMA prolonged the acute subjective effects of MDMA compared with the single dose (mean ± SD, 5.6 ± 1.8 h vs . 4.6 ± 1.2 h, p = 0.001), while no differences in subjective or autonomic peak effects were observed. Acute (0–9 h) and subacute (up to 3 days) adverse effects were more common after both MDMA conditions than placebo. These results indicate that acute MDMA effects can be prolonged by using a booster dose, as intended in clinical trials of MDMA-AT. Whether this translates into clinical benefit remains to be investigated.

Mitochondrial dysfunction is a central feature of aging, driving bioenergetic decline, increased oxidative stress, and increased vulnerability to neurodegenerative diseases. Human induced pluripotent stem cells (iPSCs) and iPSC-derived neurons provide powerful models to study these processes. Ginkgo biloba extract GBE LI1370 (GBE) has demonstrated antioxidant and mitochondria-protective properties in preclinical models, including improvements in mitochondrial membrane potential, reduction in reactive oxygen species, and enhanced neuronal survival. However, its effects on mitochondrial function in human iPSCs and their differentiated derivatives in the context of aging have not yet been investigated. This study evaluated the mitochondrial protective effects of GBE (100 µg/mL) in an established iPSC-based model of aging and in neurons and astrocytes derived from aged iPSCs. Mitochondrial parameters, including ATP production, mitochondrial membrane potential (MMP), mitochondrial reactive oxygen species (mtROS), superoxide levels, and mitochondrial respiration, were assessed. Aged iPSCs exhibited reduced ATP production and MMP, together with increased mtROS and superoxide levels compared to young controls. Astrocytes derived from aged iPSCs also displayed mitochondrial dysfunction. Treatment with GBE for 24 h increased ATP production and MMP, reduced oxidative stress, and improved mitochondrial respiration in both young and aged iPSCs, as well as in aged iPSC-derived neurons and astrocytes. These preliminary donor-based findings support further investigation of GBE-associated mitochondrial responses in human donor-derived cellular models of aging and warrant validation in larger donor cohorts.

Based on its in vitro profile and preliminary evidence, 4-bromo-2,5-dimethoxyphenethylamine (2C-B) may have psychoactive properties that are similar to 3,4-methylenedioxymethamphetamine (MDMA) and psilocybin, which are investigated for the treatment of posttraumatic stress disorder and depressive disorders. We compared acute effects of 2C-B (10, 20, and 30 mg), 125 mg MDMA, and 25 mg psilocybin in 24 healthy participants (12 women, 12 men) using a double-blind, randomized, placebo-controlled, crossover design. Outcome measures included acute subjective effects, autonomic effects, adverse effects, effects on emotional and cognitive empathy, plasma oxytocin and neurophysin I concentrations, and pharmacokinetics up to 9 h. 2C-B produced dose-dependent subjective effects, with the 30 mg dose exerting comparable “any drug effects” to MDMA but lower “any drug effects” than psilocybin. Only psilocybin induced “bad drug effects” and “anxiety” compared with placebo. The 30 mg dose of 2C-B induced psychedelic-type alterations of state of consciousness and increased emotional empathy similarly to MDMA. The average subjective effect duration of 30 mg 2C-B was 4.9 h and similar to MDMA (4.8 h) and shorter than psilocybin (6.1 h). MDMA produced the highest cardiovascular stimulation, followed by psilocybin and 2C-B. Only MDMA increased plasma oxytocin and neurophysin I concentrations. 2C-B exhibited dose-proportional pharmacokinetics, with a plasma elimination half-life of ~1.3 h. The 30 mg dose of 2C-B induced entactogenic and psychedelic effects similarly to MDMA and psilocybin, respectively. MDMA is more cardiostimulant than psilocybin and 2C-B. At the tested dose-level, psilocybin is more distressing than MDMA and 2C-B. These results may assist with dose-finding for future 2C-B research and provide a direct comparison with standard doses of the prototypical compounds MDMA and psilocybin. Trial registration: ClinicalTrials.gov identifier: NCT05523401.

N , N -dimethyltryptamine (DMT) is a serotonergic psychedelic that produces short-lived peak effects when administered intravenously as a bolus dose. Initial trials suggested therapeutic effects of DMT in depressive disorders. However, systematic data on dose-dependent pharmacokinetics and acute effects of intravenous bolus DMT administration are currently lacking. We used a double-blind, randomized, placebo-controlled, crossover design in 20 healthy participants who received placebo and DMT (5, 10, 15, and 20 mg) within a single test session. In a separate study arm, we used an open-label, DMT dose-escalation administration design where 16 participants received stepwise increases of 5 mg DMT until reaching a maximally tolerated dose (max. 25 mg). Outcome measures included subjective effects, autonomic effects, adverse effects, and pharmacokinetics that were assessed up to 55 min after each bolus administration. Bolus DMT doses induced very strong subjective effects with a very rapid onset and peak within the first 2 min after administration. Subjective effects declined quickly and subsided completely within 12–30 min, consistent with the short elimination half-life of approximately 6–7 min. A ceiling effect for peak subjective effects was reached at the 15 mg dose. No tolerance was observed to acute effects of DMT. The tolerability markedly improved with open-label dose-escalation compared with double-blinded, randomized administration, and at equivalent dose levels, subjective effects were rated as less intense. These findings highlight the impact of blinding and expectancy on the subjective experience and suggest that individual dose-escalation may improve tolerability and help with dose selection for future DMT studies.

Mitochondrial dysfunction is an early driver of Alzheimer’s disease (AD), and the decline in sex hormones, including 17β-estradiol (E2), at menopause has been linked to AD risk in women. While E2 exerts potent neuroprotective and mitochondrial-regulatory effects, its clinical utility in estrogen replacement therapy (ERT) may be limited by thrombotic and oncologic risks. Estetrol (E4), a fetal estrogen with a selective safety profile, may represent a promising alternative. This study evaluated the impact of E4 on mitochondrial bioenergetics and neuronal morphology in human SH-SY5Y neuroblastoma cells, including models of AD-related amyloidopathy (amyloid precursor protein overexpression) and tauopathy (P301Ltau mutation overexpression). E4 significantly enhanced ATP levels, mitochondrial membrane potential, and oxidative respiration in all cell models, notably outperforming E2 in P301L cells. E4 also promoted significant neurite outgrowth, alleviating deficits observed in AD models. In addition, we demonstrated that the bioenergetic effects of E4 were mediated by the estrogen receptors ERα, ERβ, and GPER1. Furthermore, E4 modulated the expression of key mitochondrial genes, specifically upregulating the phosphate carrier SLC25A23 while downregulating the complex I subunit NDUFA1. In conclusion, E4 improves mitochondrial health and supports neuronal integrity via a multi-receptor mechanism, highlighting its potential as a safe neuroprotective therapy for AD.

Tauopathies are neurodegenerative diseases characterized by the abnormal accumulation of tau protein in neurons, leading to cognitive impairment. A common feature of these disorders is mitochondrial dysfunction, which leads to bioenergetic deficits and contributes to neuronal cell death. As neurons have high energy demands, impaired mitochondrial function directly affects their viability and function. Thus, mitochondria represent an attractive target for neuroprotective strategies in tauopathies. Mitochondrial transplantation (MT) is an emerging therapeutic approach to restoring cellular bioenergetics. Although MT has shown promise in various models of brain diseases, its efficacy has not been evaluated in the context of tau-induced mitochondrial dysfunction. This study examines the impact of MT on healthy cells and in a cellular model of tauopathy. Mitochondria were freshly isolated from astrocytic cells and transplanted into healthy SH-SY5Y neuroblastoma cells and SH-SY5Y cells overexpressing the P301L tau mutation, for 24 and 48 h. Our results demonstrate that MT enhances cell viability, ATP production, mitochondrial membrane potential, and respiration in both healthy and tau-mutant SH-SY5Y cells. In addition, MT reduced mitochondrial superoxide anion levels and promoted neurite outgrowth in both cell lines. Key bioenergetic outcomes were recapitulated in neurons derived from induced pluripotent stem cells (iPSCs) carrying the P301L tau mutation. These findings suggest that MT might be a promising therapeutic strategy to counteract mitochondrial deficits in tauopathies. Importantly, this approach positions mitochondria not as a target but as the therapeutic agent itself. Further studies are warranted to advance MT toward in vivo applications in tau-related neurodegenerative disorders.