Roeljan Wiersema

State Regulation in Adult ADHD : An Event-related Potential Study

The state regulation hypothesis postulates that poor task performance of children with ADHD is related to poor energetical state control. The current study aimed to investigate whether such a deficit persists in adult ADHD. Event-related potentials (ERPs) were recorded during administration of a Go/No-Go task that incorporated the stressor presentation rate of stimuli. It was found that males with ADHD responded slower than control males in the slow condition, which was accompanied by smaller parietal P3s, suggesting less effort allocation. No group differences were found with respect to the response inhibition measures (errors of commission and the N2 effect). In conclusion, problems in state regulation seem to persist in male adults with ADHD.

Altered circadian profiles in attention-deficit/hyperactivity disorder: An integrative review and theoretical framework for future studies

Disruptions in the sleep-wake cycle and the circadian system have been found in a wide range of psychiatric disorders and are generally correlated with clinical severity and diminished quality of life. Emerging evidence suggests similar disturbances may be found in attention-deficit/hyperactivity disorder (ADHD). Here we review the available literature on across the day fluctuations in ADHD-related processes in terms of; (i) time of day effects on behavior and activity; (ii) morningness-eveningness chronotypology; (iii) sleep/wake rhythms; and (iv) rhythmicity in neuroendocrine and neurophysiological responsiveness. On this basis, we propose a neurobiological framework to guide future study, which sees circadian effects in ADHD, along with other aspects of ADHD arousal-related deficits (e.g., cognitive energetic deficits), as being the result of dysregulated locus coeruleus function. Based on this perspective specific recommendations for future research are presented.

The role of deception in P300 memory detection

Purpose. P300 memor yd etection test is an euroscientific procedure to assess memories stored in the brain. P300 memor yd etection can and is currently applied to assess criminal suspects on recognition of critical crime information. Contrasting memor yd etection with lie detection, researchers have argued that P300 memor y detection does not involv ed eception. We empirically investigated this argument by manipulating deception between groups. Methods. Thirty-four community volunteers participated in aP 300 memor y detection test, answering either deceptively (deceptiv ec ondition) or truthfully (truth condition) to their own name. Results. P300 memor yd etection was significant in the truth condition, indicating that deceptiv er esponding is not ap rerequisite for valid P300 memor yd etection. However, there wer ec lear indications that deceptiv er esponding improve dm emor y detection. Conclusions. Deception seems involved in the P300 memor yd etection test; and deceptiv er esponding ma ya dd to test accuracy.

Sensory prediction errors are less modulated by global context in autism spectrum disorder

BACKGROUND Recent predictive coding accounts of autism spectrum disorder (ASD) suggest that a key deficit in ASD concerns the inflexibility in modulating local prediction errors as a function of global top-down expectations. As a direct test of this central hypothesis, we used electroencephalography to investigate whether local prediction error processing was less modulated by global context (i.e., global stimulus frequency) in ASD. METHODS A group of 18 adults with ASD was compared with a group of 24 typically developed adults on a well-validated hierarchical auditory oddball task in which participants listened to short sequences of either five identical sounds (local standard) or four identical sounds and a fifth deviant sound (local deviant). The latter condition is known to generate the mismatch negativity (MMN) component, believed to reflect early sensory prediction error processing. Crucially, previous studies have shown that in blocks with a higher frequency of local deviant sequences, top-down expectations seem to attenuate the MMN. We predicted that this modulation by global context would be less pronounced in the ASD group. RESULTS Both groups showed an MMN that was modulated by global context. However, this effect was smaller in the ASD group as compared with the typically developed group. In contrast, the P3b, as an electroencephalographic marker of conscious expectation processes, did not differ across groups. CONCLUSIONS Our results demonstrate that people with ASD are less flexible in modulating their local predictions (reflected in MMN), thereby confirming the central hypothesis of contemporary predictive coding accounts of ASD.

Sociodemografische determinanten van mentale gezondheid bij Vlaamse jeugd

Achtergrond en doelstelling Mentale gezondheidsproblemen bij kinderen en jongeren vormen een belasting voor de getroffen kinderen zelf, maar ook voor de maatschappij. Doelgerichte preventie en een vermindering van risico’s die verband houden met mentale problemen vergen kennis van de beïnvloedende factoren. Doelstelling van deze studie is een inschatting maken van de mentale gezondheid van Vlaamse kinderen en adolescenten en de relatie onderzoeken met sociodemografische kenmerken.