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.

To determine the prevalence of dementia associated with Parkinson's disease (PD-D) in a Brazilian sample adopting clinical and diagnostic procedures recommended by the Movement Disorders Society (MDS). Sixty-seven patients were consecutively submitted to neurological, neuropsychological and functional examinations. PD-D was established according to MDS clinical criteria (Level II) and clinical procedures for PD-D (Level I) and prevalence rate was compared between the levels adopted. Ten patients (14.9%) were diagnosed as demented by Level I criteria whereas sixteen (23.8%) were diagnosed based on Level II criteria. Level I criteria had low sensitivity in detecting PD-D (31.25%), but greater specificity (90.19). The PD-D group had significantly worse performance on all neuropsychological tests, were older (p<0.001), had an older age of onset ofdisease (p<0.01), had lower educational level (p<0.02) and had higher scores on functional scales. Current age (p=0.046) and Hoehn & Yahr score (p=0.048) were predictors for developing PD-D. Key words: Parkinson's disease, Parkinson's disease dementia, neuropsychological evaluation.Prevalência da demência associada à doença de Parkinson: uma amostra brasileira RESUMO Determinar a prevalência de demência associada à doença de Parkinson (D-DP) em uma amostra brasileira, adotando os procedimentos diagnósticos e clínicos recomendados pela Movement Disorders Society (MDS). Sessenta e sete pacientes foram submetidos à avaliação neurológica, neuropsicológica e funcional. D-DP foi estabelecida de acordo com os procedimentos (Nível I) e critérios clínicos propostos pela MDS (Nível II) e a prevalência de D-DP foi comparada entre os níveis adotados. A prevalência de D-DP encontrada pelo Nível I e II, foi de 14,9% e 23,8%, respectivamente. O Nível I apresentou baixa sensibilidade em detectar D-DP (31,25%), porém, mostrou alta especificidade (90,19%). O grupo D-DP teve desempenho significativamente inferior em todas tarefas neuropsicológicas, eram mais velhos (p<0,001), mais velhos ao início da doença (p<0,01), menos escolarizados (p<0,02) e elevados escores nas tarefas funcionais. Idade atual (p=0,046) e escore no Hoehn & Yahr (p=0,048) foram apontados como preditores do desenvolvimento de D-DP. Palavras-Chave: doença de Parkinson, demência associada à doença de Parkinson, avaliação neuropsicológica. Correspondence

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ABSTRACT. Studies investigating amnesic patients have shown the involvement of the medial temporal lobe during working memory (WM) tasks, especially when multiple items or features have to be associated. However, so far, no study has examined the relationship between episodic memory and WM components in patients with amnesia for comprehensive neuropsychological evaluation. Objective: The objective of this study was to investigate whether the null retention relates to deficits in the episodic buffer (EB) or the central executive (CE) components of WM. Methods: This study included 15 amnesic patients with mixed etiologies and 13 matched healthy controls. These 15 amnesic patients with mixed etiologies were divided into two subgroups: NUL subgroup (n=7) patients whose raw score was 0 (zero) on the Logical Memory delayed recall test and MOR subgroup (n=8) patients who recalled at least 1 item. The EB was assessed by complex span tasks, and the CE was assessed by random number generation (RNG) test. Results: EB tasks were impaired in both subgroups compared with controls. RNG was impaired in NUL (p=0.03), but not in MOR (p=0.99), subgroup. Conclusions: CE impairment hampers the retrieval mode action, preventing it from initiating the mental reconstruction of the context in which the to-be-remembered information was presented minutes ago.