Methylphenidate as a cognitive enhancer in healthy young people / Metilfenidato como ampliador cognitivo em jovens saudáveis

ABSTRACT. The so-called cognitive enhancers have been widely and increasingly used by healthy individuals who seek improvements in cognitive performance despite having no pathologies. One drug used for this purpose is methylphenidate, a first-line drug for the treatment of attention deficit hyperactivity disorder (ADHD). Objective: The aim of the present study was to test the effect of acute administration of varying doses of methylphenidate (10 mg, 20 mg, 40 mg and placebo) on a wide range of cognitive functions in healthy young people. Methods: A total of 36 young university students and graduates participated in the study. The participants underwent tests of attention and of episodic, and working memory. Results: No differences in performance were observed on any of the tests. There was a dose-dependent (40 mg > placebo) effect on self-reported wellbeing. Conclusions: According to the recent literature, psychostimulant medications, such as methylphenidate, improve performance when cognitive processes are below an optimal level, which was not the case for the subjects of the present study. We suggest the impression that methylphenidate enhances cognitive performance in healthy young people, justifying its use, may be due to improvements in subjective wellbeing promoted by the drug.

RESUMO. Os chamados ampliadores cognitivos têm sido ampla e crescentemente utilizados por indivíduos saudáveis, que apesar de não apresentarem nenhum tipo de patologia, buscam por melhoras no desempenho cognitivo. Um fármaco utilizado para este fim é o metilfenidato, droga de primeira escolha para tratamento do transtorno de déficit de atenção e hiperatividade (TDAH). Objetivo: O presente estudo teve como objetivo verificar o efeito da administração aguda de diferentes doses de metilfenidato (10, 20 e 40 mg e placebo) sobre uma ampla gama de funções cognitivas em jovens saudáveis. Métodos: Participaram do estudo 36 jovens universitários ou graduados, tendo sido realizados testes de atenção, memória operacional, episódica. Resultados: Não foram observadas diferenças no desempenho dos sujeitos em nenhum dos testes. Houve efeito na auto-avaliação de bem estar, sendo este efeito dose dependente (40 mg > placebo). Conclusão: De acordo com a literatura recente, medicações psicoestimulantes, como o metilfenidato, produzem melhoras no desempenho quando os processos cognitivos estão abaixo de um nível ótimo, o que não era o caso dos sujeitos do presente estudo. Sugerimos que a impressão de que o metilfenidato melhora o desempenho cognitivo em pessoas jovens e saudáveis se deve ao seu efeito subjetivo de bem-estar.

Methylphenidate as a cognitive enhancer in healthy young people.

The so-called cognitive enhancers have been widely and increasingly used by healthy individuals who seek improvements in cognitive performance despite having no pathologies. One drug used for this purpose is methylphenidate, a first-line drug for the treatment of attention deficit hyperactivity disorder (ADHD). OBJECTIVE: The aim of the present study was to test the effect of acute administration of varying doses of methylphenidate (10 mg, 20 mg, 40 mg and placebo) on a wide range of cognitive functions in healthy young people. METHODS: A total of 36 young university students and graduates participated in the study. The participants underwent tests of attention and of episodic, and working memory. RESULTS: No differences in performance were observed on any of the tests. There was a dose-dependent (40 mg > placebo) effect on self-reported wellbeing. CONCLUSIONS: According to the recent literature, psychostimulant medications, such as methylphenidate, improve performance when cognitive processes are below an optimal level, which was not the case for the subjects of the present study. We suggest the impression that methylphenidate enhances cognitive performance in healthy young people, justifying its use, may be due to improvements in subjective wellbeing promoted by the drug.

Os chamados ampliadores cognitivos têm sido ampla e crescentemente utilizados por indivíduos saudáveis, que apesar de não apresentarem nenhum tipo de patologia, buscam por melhoras no desempenho cognitivo. Um fármaco utilizado para este fim é o metilfenidato, droga de primeira escolha para tratamento do transtorno de déficit de atenção e hiperatividade (TDAH). OBJETIVO: O presente estudo teve como objetivo verificar o efeito da administração aguda de diferentes doses de metilfenidato (10, 20 e 40 mg e placebo) sobre uma ampla gama de funções cognitivas em jovens saudáveis. MÉTODOS: Participaram do estudo 36 jovens universitários ou graduados, tendo sido realizados testes de atenção, memória operacional, episódica. RESULTADOS: Não foram observadas diferenças no desempenho dos sujeitos em nenhum dos testes. Houve efeito na auto-avaliação de bem estar, sendo este efeito dose dependente (40 mg > placebo). CONCLUSÃO: De acordo com a literatura recente, medicações psicoestimulantes, como o metilfenidato, produzem melhoras no desempenho quando os processos cognitivos estão abaixo de um nível ótimo, o que não era o caso dos sujeitos do presente estudo. Sugerimos que a impressão de que o metilfenidato melhora o desempenho cognitivo em pessoas jovens e saudáveis se deve ao seu efeito subjetivo de bem-estar.

Levels of processing: the evolution of a framework

Although the levels of processing framework have evolved over its nearly 40 years of existence, the essence of the idea has not changed from the original. The original article published in 1972 suggests that in the encoding stage of a stimulus, there is a series of processing hierarchies ranging from the shallowest level (perceptual processing-the subject initially perceives the physical and sensory characteristics of the stimulus) to the deepest level (semantic processing-related to pattern recognition and extraction of meaning). The depth processing is associated with high levels of retention and long-term memory traces. After extensive research and criticism, the authors added several concepts that aided in a better understanding of levels of processing framework and the items that subjects can recall such as transfer-appropriate processing and robust encoding. However, there are still some gaps in this framework that call for new scientific investigations, ranging from experimental paradigms with lists of words with healthy or pathological conditions subject to neuroimaging studies to confirm, refute or improve the framework. The aim of this article is to review the publications (articles and book chapters) dating from the original article to the present day to better understand the mnemonic process in terms of levels of processing and to highlight some of its contributions.(AU)

Levels of processing: the evolution of a framework

Although the levels of processing framework have evolved over its nearly 40 years of existence, the essence of the idea has not changed from the original. The original article published in 1972 suggests that in the encoding stage of a stimulus, there is a series of processing hierarchies ranging from the shallowest level (perceptual processing-the subject initially perceives the physical and sensory characteristics of the stimulus) to the deepest level (semantic processing-related to pattern recognition and extraction of meaning). The depth processing is associated with high levels of retention and long-term memory traces. After extensive research and criticism, the authors added several concepts that aided in a better understanding of levels of processing framework and the items that subjects can recall such as transfer-appropriate processing and robust encoding. However, there are still some gaps in this framework that call for new scientific investigations, ranging from experimental paradigms with lists of words with healthy or pathological conditions subject to neuroimaging studies to confirm, refute or improve the framework. The aim of this article is to review the publications (articles and book chapters) dating from the original article to the present day to better understand the mnemonic process in terms of levels of processing and to highlight some of its contributions.

Acute glucocorticoid effects on the multicomponent model of working memory.

OBJECTIVE: In comparison with basal physiological levels, acute, high levels of cortisol affect learning and memory. Despite reports of cortisol-induced episodic memory effects, no study has used a comprehensive battery of tests to evaluate glucocorticoid effects on the multicomponent model of working memory. Here, we report the results of a double-blind, placebo-controlled, between-subjects study. METHODS: Twenty healthy young men were randomly assigned to either acute cortisol (30 mg hydrocortisone) or placebo administration. Participants were subjected to an extensive cognitive test battery that evaluated all systems of the multicomponent model of working memory, including various executive domains (shifting, updating, inhibition, planning and access to long-term memory). RESULTS: Compared with placebo, hydrocortisone administration increased cortisol blood levels and impaired working memory in storage of multimodal information in the episodic buffer and maintenance/reverberation of information in the phonological loop. Hydrocortisone also decreased performance in planning and inhibition tasks, the latter having been explained by changes in storage of information in working memory. CONCLUSIONS: Thus, hydrocortisone acutely impairs various components of working memory, including executive functioning. This effect must be considered when administering similar drugs, which are widely used for the treatment of many clinical disorders.

Assessment of working memory in patients with mesial temporal lobe epilepsy associated with unilateral hippocampal sclerosis.

OBJECTIVE: The aim of the present study was to investigate whether working memory is impaired in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), a controversial and largely unexplored matter. METHODS: Twenty subjects with left MTLE-HS, 19 with right MTLE-HS, and 21 control right-handed subjects underwent neuropsychological assessment of episodic and semantic memory, executive functions, and specific working memory components. RESULTS: Left and right epileptogenic foci resulted in impairment of verbal and nonverbal episodic memory (verbal memory deficit greater in left MTLE-HS than in right MTLE-HS). In addition, patients with left MTLE-HS were impaired in learning paired associates, verbal fluency, and Trail Making. No differences were seen in the tests carried out to evaluate the working memory components (except visuospatial short-term memory in right MTLE-HS). CONCLUSION: In this study we did not detect reliable working memory impairment in patients with MTLE-HS with either a left or right focus in most tasks considered as tests of working memory components.

Neuropsychological assessment of current and past crack cocaine users.

BACKGROUND: Cognitive changes due to crack cocaine consumption remain unclear. METHODS: For clarification, 55 subjects were assigned to three groups: control group, crack cocaine current users, and ex-users. Participants were submitted to Mini-Mental State Examination (MMSE) and tasks evaluating executive functioning and verbal memory. Mood state was also measured. Intergroup comparisons were carried out. RESULTS: Control group performance on the MMSE was better than that of users and ex-users. Verbal memory performance for logical memory of users was impaired. Ex-users scored lower on DSST and Trail Making Test (Part B). CONCLUSION: Chronic crack cocaine use seems to disrupt general cognitive functioning (MMSE), verbal memory, and attentional resources, but findings suggest that some of these effects could be reversed by abstinence.

Serial position curve and semantic facilitation in patients with mesial temporal lobe epilepsy / Curva de posição serial e facilitação semântica em pacientes com epilepsia de lobo temporal mesial / Curva de posición serial y facilitación semantica en pacientes con epilepsia del lóbulo temporal medial

We investigated the serial position curve and semantic facilitation effect in patients with left and right mesial temporal lobe epilepsy (MTLE) with hipocampal sclerosis compared to a matched control group. Subjects (L-MTLE = 19, R-MTLE = 15, and controls = 21) were assessed by recalling word lists either with the three middle wordssemantically related or not. The total number of words recalled from both types of lists did not differ between groups. Recency was preserved, showing that short-term memory (phonological loop) is not affected in these patients. Primacy was equally present for the lists with no semantic relationships in all groups, but was absent for lists with semantically related words. The semantic facilitation effect was seen in all groups, but with a lower magnitude in the L-MTLE group, suggesting that the spread of discharges in the left hemisphere interferes with the automatic processing of semantic networks.(AU)

Nós investigamos a curva de posição serial e o efeito de facilitação semântica em pacientes com epilepsia do lobo temporal mesial (ELTM) esquerda e direita com esclerose hipocampal, comparados a um grupo controle. Os sujeitos (ELTM-E = 19, ELTM-D = 15 e controles = 21) foram submetidos ao teste de recordação livre de palavras, sendo que metade das listas de palavras continham três palavras semanticamente relacionadas inseridas nas posições intermediárias. O número total de palavras recordadas em ambos tipos de listas não diferiu entre os grupos. A recência foi preservada sugerindo que a memória de curto prazo (alça fonológica) não é afetada nestes pacientes. A primazia foi observada somente nas listas sem relacionamento semântico, independentemente do grupo. O efeito de facilitação semântica foi obtido em todos os grupos, mas com menor magnitude ao ELTM-E, sugerindo que a propagação das descargas no hemisfério esquerdo interfere com o processamento automático da rede semântica.(AU)