Methylphenidate and emotional-motivational processing in attention-deficit/hyperactivity disorder.

In line with the assumption that emotional-motivational deficits are one core dysfunction in ADHD, in one of our previous studies we observed a reduced reactivity towards pleasant pictures in adult ADHD patients as compared to controls. This was indicated by a lack of attenuation of the startle reflex specifically during pleasant pictures in ADHD patients. The first choice medical agents in ADHD, methylphenidate (MPH), is discussed to normalize these dysfunctions. However, experimental evidence in the sense of double-blind placebo-controlled study designs is lacking. Therefore, we investigated 61 adult ADHD patients twice, one time with placebo and one time with MPH with the same experimental design as in our study previously and assessed emotion processing during the presentation of pleasant, neutral and unpleasant pictures. We obtained startle reflex data as well as valence and arousal ratings in association with the pictures. As previously shown, ADHD patients showed a diminished startle attenuation during pleasant pictures while startle potentiation during unpleasant pictures was normal. Valence and arousal ratings unsuspiciously increased with increasing pleasantness and arousal of the pictures, respectively. There were no significant influences of MPH. The study replicates that ADHD patients show a reduced reactivity towards pleasant stimuli. MPH did not normalize this dysfunction. Possibly, MPH only influences emotions during more complex behavioural tasks that involve executive functions in adults with ADHD. Our results emphasize the importance for the use of double-blind placebo-controlled designs in psychopharmacological research.

Methylphenidate normalizes emotional processing in adult patients with attention-deficit/hyperactivity disorder: preliminary findings.

Emotional-motivational dysfunctions may significantly contribute to symptoms of attention-deficit/hyperactivity disorder (ADHD). Hyperactive-impulsive symptoms and sensation seeking could be the result of a search for reinforcers, and cognitive dysfunctions might be due to a low motivational drive. Emotional-motivational dysfunctions could also explain social dysfunctions in ADHD patients because they may lead to misinterpretations of emotional and social clues. Since methylphenidate (MPH) is the first choice as a pharmacological treatment in ADHD, we examined its influence on dysfunctional emotional processes. 13 adult ADHD patients were examined twice, without and after intake of MPH according to their personal medication regimen. The affect-modulated startle paradigm was used to assess physiological (affect-modulated startle response) and subjective (valence and arousal ratings) responses to pleasant, neutral and unpleasant visual stimuli. Healthy controls displayed affective startle modulation as expected, with startle attenuation and potentiation while watching pleasant and unpleasant pictures, respectively. In contrast, unmedicated ADHD patients displayed deficient responses to pleasant stimuli; no startle attenuation during the exposure to pleasant pictures was observed. However, MPH reinstated a normal affective startle modulation, as indicated by attenuation and potentiation associated with pleasant and unpleasant pictures, respectively. Valence and arousal ratings of patients were not affected by MPH. The data suggest that MPH as first choice treatment in ADHD has a positive impact on emotional processes in adult ADHD patients and points to the clinical relevance of emotional-dysfunctions in ADHD.

Brain activation for alertness measured with functional near infrared spectroscopy (fNIRS).

Alertness is a basic psychological function within the construct of attention. The neural basis of alertness has been found in the right frontotemporal cortex and the left ventrolateral prefrontal cortex. The aim of the present study was to establish the measurement of functional brain activity during alertness with functional near infrared spectroscopy (fNIRS). Therefore we measured the changes in brain oxygenation in two independent samples during an alertness condition and control conditions with 52 NIRS channels placed over the frontotemporal area. Based on a region of interest defined in the first sample (and on the literature) we showed in the second sample significantly higher activation during the alertness condition compared to the control conditions. This study proves the possibility of investigating the neural correlates of alertness using fNIRS.