Maria Teresa Araujo Silva

Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory

Previous studies have claimed that weak transcranial direct current stimulation (tDCS) induces persisting excitability changes in the human motor cortex that can be more pronounced than cortical modulation induced by transcranial magnetic stimulation, but there are no studies that have evaluated the effects of tDCS on working memory. Our aim was to determine whether anodal transcranial direct current stimulation, which enhances brain cortical excitability and activity, would modify performance in a sequential-letter working memory task when administered to the dorsolateral prefrontal cortex (DLPFC). Fifteen subjects underwent a three-back working memory task based on letters. This task was performed during sham and anodal stimulation applied over the left DLPFC. Moreover seven of these subjects performed the same task, but with inverse polarity (cathodal stimulation of the left DLPFC) and anodal stimulation of the primary motor cortex (M1). Our results indicate that only anodal stimulation of the left prefrontal cortex, but not cathodal stimulation of left DLPFC or anodal stimulation of M1, increases the accuracy of the task performance when compared to sham stimulation of the same area. This accuracy enhancement during active stimulation cannot be accounted for by slowed responses, as response times were not changed by stimulation. Our results indicate that left prefrontal anodal stimulation leads to an enhancement of working memory performance. Furthermore, this effect depends on the stimulation polarity and is specific to the site of stimulation. This result may be helpful to develop future interventions aiming at clinical benefits.

Enhancement of non-dominant hand motor function by anodal transcranial direct current stimulation

Transcranial direct current stimulation (tDCS) is a non-invasive powerful method to modulate brain activity. It can enhance motor learning and working memory in healthy subjects. To investigate the effects of anodal tDCS (1 mA, 20 min) of the dominant and non-dominant primary motor cortex (M1) on hand motor performance in healthy right-handed volunteers, healthy subjects underwent one session of both sham and active anodal stimulation of the non-dominant or dominant primary motor cortex. A blinded rater assessed motor function using the Jebsen Taylor Hand Function Test. For the non-dominant hand, active tDCS was able to improve motor function significantly-there was a significant interaction between time and condition of stimulation (p = 0.003). Post hoc tests showed a significant enhancement of JTT performance after 1 mA anodal tDCS of M1 (mean improvement of 9.41%, p = 0.0004), but not after sham tDCS (mean improvement of 1.3%, p = 0.84). For the dominant hand, however, neither active nor sham tDCS resulted in a significant change in motor performance. Our findings show that anodal tDCS of the non-dominant primary motor cortex results in motor function enhancement and thus confirm and extend the notion that tDCS can change behavior. We speculate that the under-use of the non-dominant hand with its associated consequences in cortical plasticity might be one of the reasons to explain motor performance enhancement in the non-dominant hand only.

Effect of repetitive TMS and fluoxetine on cognitive function in patients with parkinson's disease and concurrent depression

Previous studies show that cognitive functions are more impaired in patients with Parkinsons disease (PD) and depression than in nondepressed PD patients. We compared the cognitive effects of two types of antidepressant treatments in PD patients: fluoxetine (20 mg/day) versus repetitive transcranial magnetic stimulation (rTMS, 15 Hz, 110% above motor threshold, 10 daily sessions) of the left dorsolateral prefrontal cortex. Twenty‐five patients with PD and depression were randomly assigned either to Group 1 (active rTMS and placebo medication) or to Group 2 (sham rTMS and fluoxetine). A neuropsychological battery was assessed by a rater blind to treatment arm at baseline and 2 and 8 weeks after treatment. Patients in both groups had a significant improvement of Stroop (colored words and interference card) and Hooper and Wisconsin (perseverative errors) test performances after both treatments. Furthermore, there were no adverse effects after either rTMS or fluoxetine in any neuropsychological test of the cognitive test battery. The results show that rTMS could improve some aspects of cognition in PD patients similar to that of fluoxetine. The mechanisms for this cognitive improvement are unclear, but it is in the context of mood improvement.

Anxiogenic-like effect of acute and chronic fluoxetine on rats tested on the elevated plus-maze

The selective serotonin reuptake inhibitor fluoxetine (FLX) is widely prescribed for depression and anxiety-related disorders. On the other hand, enhanced serotonergic transmission is known to be classically related to anxiety. In this study, the effects of acute (5.0 mg/kg) and chronic (5.0 mg/kg, 22 days) FLX were investigated in both food-deprived and non-deprived rats tested in the elevated plus-maze. Significant main effects of the three factors (drug, food condition and administration regimen) were observed, but no interaction between them. The administration of either acute or chronic FLX resulted in an anxiogenic effect, as detected by a significant reduction in the percentage of time spent in the open arms and in the percentage of open arm entries. Food deprivation yielded an anxiolytic-like profile, probably related to changes in locomotor activity. The administration regimen resulted in an anxiolytic profile in chronically treated rats, as would be expected after 22 days of regular handling. The anxiogenic action of acute FLX is consistent with both its neurochemical and clinical profile. The discrepancy between the anxiogenic profile of chronic FLX and its therapeutic uses is discussed in terms of possible differences between the type of anxiety that is measured in the plus-maze and the types of human anxiety that are alleviated by fluoxetine.

A comparison of horse-race, bingo, and video poker gamblers in Brazilian gambling settings.

In the present study Brazilian gamblers from different settings were compared on socio-demographic characteristics, gambling behavior, and use of drugs. The SOGS was administered to 171 subjects at bingo (BG), video poker (VP), and horse-racing clubs (HR) of São Paulo. BG concentrated most women, VP the youngest and single gamblers, and HR the lowest income subjects. More VP than HR or BG gamblers reported taking time off work to gamble, as well as returning another day to win back lost money. They also had a higher number of scorable responses on the SOGS. The differences observed suggest that VP gamblers bear a greater risk of developing a pathological gambling pattern. The authors suggest that measures should be taken aimed at the prevention of pathological gambling, particularly among the young population of video poker gamblers.

Ecstasy (MDMA): effects and patterns of use reported by users in São Paulo

OBJECTIVE As there are no studies about the use of ecstasy in Brazil, our aim was to identify the effects and patterns of use of this substance among users in the city of São Paulo. METHODS Subjects were recruited through the snowball technique. Fifty-two subjects of both genders who had been using ecstasy frequently and recently were interviewed. The instrument was a self-reported and anonymous questionnaire. RESULTS The samples mean age was 24 years, mostly composed by single, college graduated middle-class subjects. Among the interviewed users, 61.6% used ecstasy at least once per week and 50% of them took one pill per episode of use and 46% more than one. Drug taking was usually performed in company of several people (63%) in contexts related to night leisure, such as rave parties (78.8%), dancing clubs (69.2%) and parties (53.8%). Ecstasy pills were mainly purchased from friends or acquaintances in order to favor a dancing mood in those places. Most subjects used ecstasy associated to other psychoactive drugs (93.3%), mainly Cannabis, followed by tobacco and LSD. The effects attributed to ecstasy were mainly positive. DISCUSSION The use of ecstasy in São Paulo has had a recreational pattern quite similar to those described in previous studies. The assessment of the use of ecstasy as positive also agrees with the findings of the literature.

Characteristics of Ecstasy users in São Paulo, Brazil

The present study was aimed at identifying patterns of Ecstasy (methylenedioxy-methamphetamine—MDMA) use in the city of São Paulo. Ecstasy users were recruited through the snowball technique. Using the same technique, a non-user control group was recruited among individuals that had never tried the drug but shared with users a similar life style. Users (N = 52) and non-users (N = 52) were interviewed in order to obtain data on socio-demographic characteristics and use of psychoactive drugs. In addition, levels of anxiety, depression and impulsiveness were assessed through Spielbergers IDATE Trace Inventory, Becks Depression Inventory and Barrat Impulsiveness Scale. Both users and non-users revealed similar socio-demographic characteristics: most subjects were middle class young heterosexual single men and women who had a college degree. Multiple drug use was more frequent among users than among non-users. Other features that were significantly more accentuated among users than among non-users were the presence of tattoos and piercings, the frequency of attending raves and the preference for electronic music. Beck Inventory results pointed to significantly lower depression scores among users. No differences were observed between groups regarding anxiety and impulsiveness scores. Although the use of Ecstasy in São Paulo is restricted to a young middle or high social class, their vanguard lifestyle tends to influence youngsters of other social extractions, so that the use of the drug may soon become widespread and thus a legitimate public health concern.The present study was aimed at identifying patterns of Ecstasy (methylenedioxymethamphetamine-MDMA) use in the city of São Paulo. Ecstasy users were recruited through the snowball technique. Using the same technique, a non-user control group was recruited among individuals that had never tried the drug but shared with users a similar life style. Users (N = 52) and non-users (N = 52) were interviewed in order to obtain data on socio-demographic characteristics and use of psychoactive drugs. In addition, levels of anxiety, depression and impulsiveness were assessed through Spielbergers IDATE Trace Inventory, Becks Depression Inventory and Barrat Impulsiveness Scale. Both users and non-users revealed similar socio-demographic characteristics: most subjects were middle class young heterosexual single men and women who had a college degree. Multiple drug use was more frequent among users than among non-users. Other features that were significantly more accentuated among users than among non-users were the presence of tattoos and piercings, the frequency of attending raves and the preference for electronic music. Beck Inventory results pointed to significantly lower depression scores among users. No differences were observed between groups regarding anxiety and impulsiveness scores. Although the use of Ecstasy in São Paulo is restricted to a young middle or high social class, their vanguard lifestyle tends to influence youngsters of other social extractions, so that the use of the drug may soon become widespread and thus a legitimate public health concern.

Validity Study of the South Oaks Gambling Screen (SOGS) among distinct groups of Brazilian gamblers

OBJETIVOS: O objetivo desse estudo e avaliar a consistencia interna e a dimensionalidade da versao da South Oaks Gambling Screen (SOGS) adaptada para uso em populacao brasileira e sua capacidade de discriminar diferentes tipos de jogadores. METODO: O estudo envolveu 217 jogadores ¾ contatados no Jockey Clube de Sao Paulo, em casas de bingo e de video poquer ¾, sendo que 46 deles haviam procurado tratamento no Ambulatorio de Jogo Patologico do Programa de Orientacao e Atendimento a Dependentes da Universidade Federal de Sao Paulo.Entre eles 96 eram jogadores sociais e 75 eram classificados como provaveis jogadores patologicos. RESULTADOS: As diferencas das medias de pontuacoes das subamostras foram estatisticamente significantes, discriminando jogadores sociais e jogadores patologicos entrevistados em local de jogo e amostra clinica. A SOGS, em sua versao integral de 20 itens, apresentou consistencia interna medida pelo modelo Alfa de Cronbach de 0,9304. A analise fatorial da estrutura da escala resultou em uma solucao de tres dimensoes, respondendo por 58,6% da variabilidade total dos dados na amostra: um primeiro fator constituido preponderantemente por questoes referentes a consequencias do comportamento de jogar; um segundo fator reunindo predominantemente questoes relativas ao proprio comportamento de jogar dos jogadores patologicos; e um terceiro fator, menos decisivo no conjunto e composto de apenas duas questoes, parecendo ser um fator hibrido de dificil interpretacao. CONCLUSOES: A versao adaptada para o Brasil da SOGS mostrou-se um instrumento util para discriminar jogadores brasileiros patologicos de jogadores nao-patologicos, como tambem diferenciou os grupos clinico e nao-clinico de jogadores patologicos, identificando graus distintos de gravidade.

Pathological and nonpathological gamblers: A survey in gambling settings

In this first study on gambling in Brazil, pathological and non-pathological gamblers were surveyed at three bingo clubs, one video poker club, and one horse-racing club in São Paulo. The South Oaks Gambling Screen and a questionnaire were administered to 171 subjects. When compared to nonpathological gamblers, a significantly higher proportion of pathological gamblers played cards, horse races, video poker, and dice in their lifetime. The two groups were similar with respect to socially acceptable games such as lotteries, bingo, sports, and the stock market. No significant differences were observed in drug consumption except for a higher lifetime consumption of tobacco among pathological gamblers. Only 4.9% of the gamblers sought help for gambling-related problems, suggesting that gambling is not generally perceived as a mental health problem by these subjects.

Indatraline: Synthesis and Effect on the Motor Activity of Wistar Rats

A new approach for the synthesis of indatraline was developed using as the key step an iodine(III)-mediated ring contraction of a 1,2-dihydronaphthalene derivative. Behavioral tests were conducted to evaluate the effect of indatraline and of its precursor indanamide on the motor activity of Wistar rats. Specific indexes for ambulation, raising and stereotypy were computed one, two and three hours after i.p. drug administration. Indatraline effects on motor activity lasted for at least three hours. On the other hand, no significant differences in motor activity were observed using indanamide. The results suggest that indatraline has a long lasting effect on motor activity and add evidence in favor of the potential use of that compound as a substitute in cocaine addiction.