Effects of acute tryptophan depletion on executive function in healthy male volunteers

BACKGROUND: Neurocognitive impairment is frequently described in a number of psychiatric disorders and may be a direct consequence of serotonergic dysfunction. As impairments in executive functions are some of the most frequently described, the purpose of this study was to examine the performance of normal volunteers on a range of executive tasks following a transient reduction of central serotonin (5-HT) levels using the method of acute tryptophan depletion (ATD). METHODS: Fifteen healthy male subjects participated in a within-subject, double-blind, counterbalanced crossover study. ATD was induced by ingestion of a 100 g amino-acid drink. Executive function was evaluated using the Wisconsin Card Sorting Test, Stroop, Verbal Fluency and Trail Making. Visual analogue scales were administered to assess mood. RESULTS: Plasma free and total tryptophan concentrations were significantly reduced by the depleting drink (P < 0.001). ATD selectively improved motor speed/ attention on the Trails A test (P = 0.027), with no effect on subjective ratings of mood. Interaction effects between drink and the order of drink administration were observed on most neurocognitive tests. CONCLUSIONS: The improvement in simple motor speed/ attention following ATD is in keeping with the ascribed role of 5-HT in the cortex, however performance on tests of executive function is not robustly altered. The presence of interaction effects on most tasks suggests that subtle changes may occur but are masked, possibly by simple learning effects, in the context of a crossover design. This has implications for the design of future studies, particularly those examining executive functions

Neurobiologia do transtorno de humor bipolar e tomada de decisão na abordagem psicofarmacológica

O Transtorno do Humor Bipolar (THB) caracteriza-se por oscilações do humor que causam prejuízos significativos no âmbito biopsicossocial. O interesse da comunidade científica por este transtorno vem aumentando nos últimos cinco anos em função de sua crescente prevalência associada ao refinamento diagnóstico, à ampliação do arsenal terapêutico e ao conhecimento dos avanços nas pesquisas da neurobiologia do transtorno. A presente revisão aborda questões diagnosticas e terapêuticas aplicadas à neurobiologia dos THB, relacionando-as diretamente à terapêutica dos quadros de mania, hipomania, estados mistos, depressão bipolar e ciclagem rápida, da infância à idade adulta. São revisados criticamente importantes estudos realizados com diferentes fármacos potencialmente eficazes como estabilizadores do humor, nos diversos subdiagnósticos do THB. São analisados fármacos, tais como o lítio, anticonvulsivantes, antipsicóticos, benzodiazepínicos, bloqueadores dos canais de cálcio e hormônio tireoideo, bem como as possíveis bases biológicas para seus efeitos terapêuticos. Em síntese, este trabalho aborda os avanços da psicofarmacologia cuja eficácia é comprovada nos subtipos do THB, procurando relacioná-los com a neurobiologia deste transtorno.Bipolar Disorder (BD) is characterized by mood swings that cause significant impairment in social, occupational, or other areas of functioning. During the last years, new insights have been provided in the diagnosis, etiology, neurobiological basis and treatment of bipolar disorder. This paper emphasizes recent studies related to some diagnostic and therapeutic aspects during manic episode, hypomanic, mixed episode, bipolar depression and rapid cycling, in children, adolescents and adults. Studies using proposed mood stabilizers, which present adequate metodological basis, including double–blind, controlled studies and which presented a significant number of patients were included and critically evaluated in this revision. Drugs such as the lithium, anticonvulsants, antipsychotics, benzodiazepines, calcium channels blockers and thyroid augmentation are proposed to be effective in certain diagnostic profiles. The possible biological bases for these drugs therapeutic effects are also revised. In summary, this article focuses on recent and important psychopharmacological progresses on the treatment of BD subtypes. Furthermore, the revision presents possible biological basis to explain the therapeutic profile of these drugs