RESUMO
AIMS: Ayahuasca is a traditional South American psychoactive beverage used in Amazonian shamanism, and in the religious ceremonies of Brazilian-based syncretic religious groups with followers in the US and several European countries. This tea contains measurable amounts of the psychotropic indole N,N-dimethyltryptamine (DMT), and beta-carboline alkaloids with MAO-inhibiting properties. In a previous report we described a profile of stimulant and psychedelic effects for ayahuasca as measured by subjective report self-assessment instruments. In the present study the cerebral bioavailability and time-course of effects of ayahuasca were assessed in humans by means of topographic quantitative-electroencephalography (q-EEG), a noninvasive method measuring drug-induced variations in brain electrical activity. METHODS: Two doses (one low and one high) of encapsulated freeze-dried ayahuasca, equivalent to 0.6 and 0.85 mg DMT kg(-1) body weight, were administered to 18 healthy volunteers with previous experience in psychedelic drug use in a double-blind crossover placebo-controlled clinical trial. Nineteen-lead recordings were undertaken from baseline to 8 h after administration. Subjective effects were measured by means of the Hallucinogen Rating Scale (HRS). RESULTS: Ayahuasca induced a pattern of psychoactive effects which resulted in significant dose-dependent increases in all subscales of the HRS, and in significant and dose-dependent modifications of brain electrical activity. Absolute power decreased in all frequency bands, most prominently in the theta band. Mean absolute power decreases (95% CI) at a representative lead (P3) 90 min after the high dose were -20.20+/-15.23 microV2 and -2.70+/-2.21 microV2 for total power and theta power, respectively. Relative power decreased in the delta (-1.20+/-1.31% after 120 min at P3) and theta (-3.30+/-2.59% after 120 min at P3) bands, and increased in the beta band, most prominently in the faster beta-3 (1.00+/-0.88% after 90 min at P3) and beta-4 (0.30+/-0.24% after 90 min at P3) subbands. Finally, an increase was also seen for the centroid of the total activity and its deviation. EEG modifications began as early as 15-30 min, reached a peak between 45 and 120 min and decreased thereafter to return to baseline levels at 4-6 h after administration. CONCLUSIONS: The central effects of ayahuasca could be objectively measured by means of q-EEG, showing a time pattern which closely paralleled that of previously reported subjective effects. The modifications seen for the individual q-EEG variables were in line with those previously described for other serotonergic psychedelics and share some features with the profile of effects shown by pro-serotonergic and pro-dopaminergic drugs. The q-EEG profile supports the role of 5-HT2 and dopamine D2-receptor agonism in mediating the effects of ayahuasca on the central nervous system.
Assuntos
Banisteriopsis , Preparações de Plantas/farmacologia , Psicotrópicos/farmacologia , Adulto , Bebidas , Disponibilidade Biológica , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Estudos Cross-Over , Método Duplo-Cego , Eletroencefalografia , Feminino , Humanos , Masculino , Preparações de Plantas/efeitos adversos , Preparações de Plantas/farmacocinética , Psicotrópicos/efeitos adversos , Psicotrópicos/farmacocinética , América do Sul , Fatores de TempoRESUMO
Num estudo duplo-cego controlado com placebo sobre a eficácia terapêutica e os efeitos centrais da nicergolina, um alcalóide do Ergot com açäo metabólica, antitrombótica e vasoativa, foram incluídos 112 pacientes com demência leve e moderada, diagnosticada de acordo com os critérios do DSM III-R (MMS 13-25), que viviam em lares para aposentados. Cinqüenta e seis deles foram subdiagnosticados como demência senil do tipo Alzheimer (DSTA), 56 como demência multi-infarto (DMI), com base em tomogafia computadorizada e em avaliaçöes de Hachinski (menor ou igual 49 DSTA, maior ou igual 7 DMI). Eles receberam, após um período de tratamento de duas semanas (placebo), randomizados por oitos semanas, 2 x 30 mg de nicergolina (NIC) ou 2 x 1 de placebo (PLAC) via oral...