INTRODUCTION Nicotine and methylphenidate are putative cognitive enhancers in healthy and patient populations. Although they stimulate different neurotransmitter systems, they have been shown to enhance performance on overlapping measures of attention. So far, there has been no direct comparison of the effects of these two stimulants on behavioural performance or brain function in healthy human...

INTRODUCTION Recent evidence suggests that attention deficit hyperactivity disorder (ADHD) is associated with a range of brain functional connectivity abnormalities, with one of the most prominent being reduced inhibition of the default mode network (DMN) while performing a cognitive task. In this study, we examine the effects of a methylphenidate dose on brain functional connectivity in boys d...

Increases in dopamine concentration in limbic brain regions have been postulated to underlie the reinforcing effects of psychostimulant drugs in laboratory animals. However, neither the qualitative nor the quantitative relationship between drug-induced increases in brain dopamine and the reinforcing effects of psychostimulant drugs have been investigated in humans. Positron emission tomograph a...

BACKGROUND/AIM One of the most common psychiatric disorders in children is attention-deficit/hyperactivity disorder, which is treated extensively by methylphenidate. This study investigates the assessment of the effects of methylphenidate on histopathologic and histomorphometric changes of the testes and serum levels of gonadotropin in mice. MATERIALS AND METHODS In this study, 36 adult male ...

OBJECTIVES To study in more depth the relationship between type, dose, or duration of methylphenidate offered to children and adolescents with attention deficit hyperactivity disorder and their risks of gastrointestinal adverse events based on our Cochrane systematic review. METHODS AND FINDINGS We use data from our review including 185 randomised clinical trials. Randomised parallel-group tr...

BACKGROUND Psychostimulant medication, most commonly the catecholamine agonist methylphenidate, is the most effective treatment for attention-deficit/hyperactivity disorder (ADHD). However, relatively little is known on the mechanisms of action. Acute effects on brain function can elucidate underlying neurocognitive effects. We tested methylphenidate effects relative to placebo in functional ma...

By blocking dopamine and norepinephrine transporters, methylphenidate affects cognitive performance and regional brain activation in healthy individuals as well as those with neuropsychiatric disorders. Resting-state connectivity evaluates the functional integrity of a network of brain regions. Here, we examined how methylphenidate effects resting-state functional connectivity of the dorsal str...

OBJECTIVES The US Agency for Healthcare Research and Quality sponsored a comparative effectiveness review of interventions for preschoolers at risk for attention-deficit/hyperactivity disorder (ADHD). METHODS Medline, Cochrane CENTRAL, Embase, PsycInfo, and Education Resources Information Center were searched from 1980 to November 24, 2011. Selected studies were comparative, and enrolled chil...

Amphetamine-like psychostimulants, including methylphenidate, have been shown to produce two opposing effects on dopamine (DA) neurons: a DA receptor-mediated feedback inhibition and a non-DA receptor-mediated excitation. To test whether the latter effect is mediated through the prefrontal cortex (PFC), we made dual-site recordings from the PFC and ventral tegmental area (VTA). Consistent with ...

OBJECTIVES The aim of this randomized clinical trial was to assess the efficacy of memantine versus methylphenidate in the treatment of children with attention deficit hyperactivity disorder. METHOD Forty participants (34 boys and 6 girls) aged 6-11 who were diagnosed with attention deficit hyperactivity disorder based on (DSM-IV-TR) criteria were selected for this study. The participants wer...