Influence of Age, Circadian and Homeostatic Processes on Inhibitory Motor Control: A Go/Nogo Task Study

INTRODUCTION: The contribution of circadian system and sleep pressure influences on executive performance as a function of age has never been studied. The aim of our study was to determine the age-related evolution of inhibitory motor control (i.e., ability to suppress a prepotent motor response) and sustained attention under controlled high or low sleep pressure conditions. METHODS: 14 healthy young males (mean age = 23 ± 2.7; 20-29 years) and 11 healthy older males (mean age = 68 ± 1.4; 66-70 years) were recruited. The volunteers were placed for 40 hours in "constant routine". In the "Sleep Deprivation SD" condition, the volunteer was kept awake for 40 hours to obtain a high sleep pressure condition interacting with the circadian process. In the "NAP" condition, the volunteer adopted a short wake/sleep cycle (150/75 min) resulting in a low sleep pressure condition to counteract the homeostatic pressure and investigate the circadian process. Performances were evaluated by a simple reaction time task and a Go/Nogo task repeated every 3H45. RESULTS: In the SD condition, inhibitory motor control (i.e., ability to inhibit an inappropriate response) was impaired by extended wakefulness equally in both age groups (P<.01). Sustained attention (i.e. ability to respond accurately to appropriate stimuli) on the executive task decreased under sleep deprivation in both groups, and even more in young participants (P<.05). In the NAP condition, age did not influence the time course of inhibitory motor control or sustained attention. In the SD and NAP conditions, older participants had a less fluctuating reaction time performance across time of day than young participants (P<.001). CONCLUSION: Aging could be a protective factor against the effects of extended wakefulness especially on sustained attention failures due to an attenuation of sleep pressure with duration of time awake

The Neural Basis of Decision-Making and Reward Processing in Adults with Euthymic Bipolar Disorder or Attention-Deficit/Hyperactivity Disorder (ADHD)

Attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder (BD) share DSM-IV criteria in adults and cause problems in decision-making. Nevertheless, no previous report has assessed a decision-making task that includes the examination of the neural correlates of reward and gambling in adults with ADHD and those with BD

Comment évaluer l’efficacité d’un antipsychotique d’action prolongée au moyen d’un essai clinique ?

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Lack of insight may predict impaired decision making in manic patients.

OBJECTIVES: The tendency to engage in risky behaviours is a core feature of the manic episodes of bipolar disorder. The aim of this study was to establish whether this characteristic can be quantified with a laboratory measure of decision making [the Iowa Gambling Task (IGT)] and to determine clinical correlates of the IGT performance in mania. METHODS: Inpatients with acute mania (n = 45) and healthy volunteers (n = 45) were assessed on the IGT. Affective symptomatology was assessed with the Young Mania Rating Scale and Hamilton Depression Rating Scale, and item scores were subjected to factor analysis. Multivariate regression was used to assess clinical predictors of impaired decision making in the manic patients. RESULTS: On the IGT, manic patients selected more cards from the risky decks than healthy controls, and showed little capacity to learn from incurred losses. In a multivariate analysis, impaired decision making ability in the manic patients was significantly predicted by a symptom factor associated with lack of insight. CONCLUSIONS: Manic patients clearly show defects in decision making, which are strongly related to their lack of insight. Neural circuitry supporting effective decision making, including the ventromedial prefrontal cortex and somatosensory cortex, may be implicated in the pathophysiology of acute mania

Quel est le rôle des tests et examens complémentaires dans un essai clinique en psychiatrie ?

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Differential semantic processing in patients with schizophrenia versus bipolar disorder: an N400 study

International audienceOBJECTIVE: Both bipolar disorder (BD) and schizophrenia (SZ) are associated with language and thought symptoms that probably reflect a semantic memory-related impairment. We conducted a preliminary study to explore the nature of semantic processing in these disorders, using event-related potentials (ERPs).METHODS: Twelve patients with BD, 10 patients with SZ and a matched group of 21 healthy controls (HC) underwent EEG recording while they heard sentences containing homophones or control words and performed a semantic ambiguity resolution task on congruent or incongruent targets.RESULTS: Mean N400 amplitude differed between groups for homophones. Patients with SZ made more resolution errors than HC and exhibited a greater N400 congruity effect in ambiguous conditions than BD. In BD, the opposite N400 congruity effect was observed in ambiguous conditions.CONCLUSION: Results indicated differences in semantic processing between BD and SZ. Further studies with larger populations are needed in order to develop neurophysiological markers of these disorders