Kerstin Krauel

Hunger and satiety in anorexia nervosa: fMRI during cognitive processing of food pictures.

Neuroimaging studies of visually presented food stimuli in patients with anorexia nervosa have demonstrated decreased activations in inferior parietal and visual occipital areas, and increased frontal activations relative to healthy persons, but so far no inferences could be drawn with respect to the influence of hunger or satiety. Thirteen patients with AN and 10 healthy control subjects (aged 13-21) rated visual food and non-food stimuli for pleasantness during functional magnetic resonance imaging (fMRI) in a hungry and a satiated state. AN patients rated food as less pleasant than controls. When satiated, AN patients showed decreased activation in left inferior parietal cortex relative to controls. When hungry, AN patients displayed weaker activation of the right visual occipital cortex than healthy controls. Food stimuli during satiety compared with hunger were associated with stronger right occipital activation in patients and with stronger activation in left lateral orbitofrontal cortex, the middle portion of the right anterior cingulate, and left middle temporal gyrus in controls. The observed group differences in the fMRI activation to food pictures point to decreased food-related somatosensory processing in AN during satiety and to attentional mechanisms during hunger that might facilitate restricted eating in AN.

Enhanced gamma-band activity in ADHD patients lacks correlation with memory performance found in healthy children

Previous electrophysiological as well as imaging research has contributed to the understanding of impairments in attention, executive functions, and memory in patients with attention-deficit/hyperactivity disorder (ADHD). However, there is a lack of studies investigating ADHD related differences in the gamma range of human electroencephalogram (EEG), although gamma activity is strongly associated with cognitive processes impaired in ADHD patients and is also modulated by dopamine polymorphisms linked with ADHD. To close this gap, the present study compared gamma activity in ADHD children with that of healthy controls and correlated it with memory performance. EEG was recorded from 13 ADHD patients as well as 13 healthy control subjects during the encoding phase of a visual memory paradigm. In a subsequent recognition test, participants had to judge pictures as being old or new. Analysis of evoked gamma-band responses (GBRs) during stimulus encoding revealed a strong task-related enhancement for ADHD patients in parieto-occipital areas. Interestingly, this augmentation was not associated with recognition performance, whereas healthy subjects exhibited a strong positive correlation between evoked gamma activity during stimulus encoding and subsequent recognition performance. We interpret this finding as evidence of enhanced excitation levels and unspecific activation of processing resources in ADHD patients. Furthermore, enhanced GBRs in ADHD could also indicate a decrease of neuronal signal-to-noise ratio, partially caused by the genetic variations within the dopaminergic pathway of ADHD patients. The involved genetic polymorphisms have been shown to modulate evoked GBRs, which therefore could be a possible marker of impaired neurotransmission in ADHD.

Biomarkers for attention-deficit/hyperactivity disorder (ADHD). A consensus report of the WFSBP task force on biological markers and the World Federation of ADHD

Abstract Objective. Psychiatric “nosology” is largely based on clinical phenomenology using convention-based diagnostic systems not necessarily reflecting neurobiological pathomechanisms. While progress has been made regarding its molecular biology and neuropathology, the phenotypic characterization of ADHD has not improved. Thus, validated biomarkers, more directly linked to the underlying pathology, could constitute an objective measure for the condition. Method. The task force on biological markers of the World Federation of Societies of Biological Psychiatry (WFSBP) and the World Federation of ADHD commissioned this paper to develop a consensus report on potential biomarkers of ADHD. The criteria for biomarker-candidate evaluation were: (1) sensitivity > 80%, (2) specificity > 80%, (3) the candidate is reliable, reproducible, inexpensive, non-invasive, easy to use, and (4) confirmed by at least two independent studies in peer-reviewed journals conducted by qualified investigators. Results. No reliable ADHD biomarker has been described to date, but some promising candidates (e.g., olfactory sensitivity, substantial echogenicity) exist. A problem in the development of ADHD markers is sample heterogeneity due to aetiological and phenotypic complexity and age-dependent co-morbidities. Conclusions. Most likely, no single ADHD biomarker can be identified. However, the use of a combination of markers may help to reduce heterogeneity and to identify homogeneous subtypes of ADHD.

Impact of emotional salience on episodic memory in attention-deficit/hyperactivity disorder: A functional magnetic resonance imaging study

BACKGROUND Patients with attention-deficit/hyperactivity disorder (ADHD) show episodic memory deficits especially in complex memory tasks. We investigated the neural correlates of memory formation in ADHD and their modulation by stimulus salience. METHODS We recorded event-related functional magnetic resonance imaging during an episodic memory paradigm with neutral and emotional pictures in 12 male ADHD subjects and 12 healthy adolescents. RESULTS Emotional salience did significantly augment memory performance in ADHD patients. Successful encoding of neutral pictures was associated with activation of the anterior cingulate cortex (ACC) in healthy adolescents but with activation of the superior parietal lobe (SPL) and precuneus in ADHD patients. Successful encoding of emotional pictures was associated with prefrontal and inferior temporal cortex activation in both groups. Healthy adolescents, moreover, showed deactivation in the inferior parietal lobe. CONCLUSIONS From a pathophysiological point of view, the most striking functional differences between healthy adolescents and ADHD patients were in the ACC and SPL. We suggest that increased SPL activation in ADHD reflected attentional compensation for low ACC activation during the encoding of neutral pictures. The higher salience of emotional stimuli, in contrast, regulated the interplay between ACC and SPL in conjunction with improving memory to the level of healthy adolescents.

Altered evoked gamma-band responses reveal impaired early visual processing in ADHD children.

Neurophysiological studies yield contrary results whether attentional problems of patients with attention-deficit/hyperactivity disorder (ADHD) are related to early visual processing deficits or not. Evoked gamma-band responses (GBRs), being among the first cortical responses occurring as early as 90ms after visual stimulation in human EEG, have been assigned a pivotal role in early visual processing. In particular, they are involved in memory matching processes and are enhanced when known stimuli are processed. The current study examined whether evoked GBR patterns during early memory matching processes could be indicative of an early visual processing deficit in ADHD patients. EEG was recorded from 13 young ADHD patients as well as 13 age-matched healthy participants. Both groups performed a simple forced choice reaction task employing line drawings of either known real-world items with representations in long-term memory or physically similar unknown items without such representations. Evoked GBRs of ADHD patients did not differentiate between known and unknown items. However, in healthy children, evoked GBRs were enhanced when stimuli matched a representation stored in memory. This finding indicates disadvantages at early visual processing stages in ADHD patients: In contrast to healthy participants, ADHD children lack an early memory based classification, possibly resulting in an impaired ability to rapidly reallocate attentional resources to relevant stimuli. These findings suggest that impaired early automatic stimulus classification in ADHD patients could be involved in deficits of selective and sustained attention.

Psychological distress in cancer patients with underage children: gender-specific differences.

Findings on gender differences in the psychological distress of cancer patients have been inconsistent. The objectives of the current study were to examine whether being a parent differentially modulates anxiety and depression in men and women and to compare whether psychological distress differs in male and female patients with and without children.

Methylphenidate does not improve interference control during a working memory task in young patients with attention-deficit hyperactivity disorder.

Patients with attention-deficit/hyperactivity disorder (ADHD) show deficits in working memory (WM) which may be related to prefrontal dysfunction. Methylphenidate (MPH) can restore WM deficits in ADHD by enhancing prefrontal activity. At the same time, changes in striatal activation could cause ADHD patients to be more interference-sensitive during working memory tasks. However, it is unclear whether MPH reduces WM distractibility in ADHD. In this fMRI study, 12 ADHD patients and 12 healthy controls participated on two separate days in a delayed-match-to-sample test. During the delay interval, a distractor stimulus was presented in half of the trials. Children and adolescents with ADHD received MPH only on one of the two sessions. Behavioral data analyses revealed that MPH normalized WM in ADHD. However, MPH did not improve WM performance when a distractor was presented during the delay interval. Functional images showed that MPH enhanced prefrontal activity during the delay in ADHD patients when no distractor was present. If the delay was interrupted by a distractor, only healthy controls showed activation of the caudate. In patients with ADHD, however, in line with behavioral data, MPH did not enhance caudate activity. In healthy youth, caudate activity is involved in interference control allowing the successful maintenance of information in working memory even in the presence of distraction. Our findings suggest that interference control, linked to caudate activity, is not adequately enhanced by MPH in ADHD.

When a parent has cancer: challenges to patients, their families and health providers

At least 14% of cancer patients live with minor children. Being a parent with cancer has far-reaching consequences for individual treatment decision-making and quality of life in patients and their families. Even though the majority of children and adolescents do not show clinically relevant symptoms of psychopathology, worries about the survival of the parent and the future development of the family are present, and experienced as distressing, in most children. Open communication by parents and clinicians has been found to be of major importance for children and adolescents in adjusting to parental cancer. Support for parents with cancer on relevant parenting issues, starting in the diagnostic phase, should be acknowledged as an important facet of cancer care to reduce the psychosocial burden for cancer patients and their families.

Modulation of pre-attentive spectro-temporal feature processing in the human auditory system by HD-tDCS

The present study examined the functional lateralization of the human auditory cortex (AC) for pre‐attentive spectro‐temporal feature processing. By using high‐definition transcranial direct current stimulation (HD‐tDCS), we systematically modulated neuronal activity of the bilateral AC. We assessed the influence of anodal and cathodal HD‐tDCS delivered over the left or right AC on auditory mismatch negativity (MMN) in response to temporal as well as spectral deviants in 12 healthy subjects. The results showed that MMN to temporal deviants was significantly enhanced by anodal HD‐tDCS applied over the left AC only. Our data indicate a left hemispheric dominance for the pre‐attentive processing of low‐level temporal information.

Increased Echogenicity of the Substantia Nigra in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder

BACKGROUND Recent neurobiological models on attention-deficit/hyperactivity disorder (ADHD) as well as findings from imaging studies suggest a crucial involvement of dopaminergic midbrain nuclei, especially the substantia nigra (SN), in the pathogenesis of ADHD symptoms. The current study aimed to investigate whether alterations in the sonographic features of the SN could serve as a biological marker in ADHD patients. METHODS The current study employed transcranial sonography in 29 children and adolescents with ADHD and 27 healthy control participants to assess midbrain abnormalities in ADHD. RESULTS The ADHD patients showed an increase in echogenic size of the SN that was correlated with symptoms of inattention, hyperactivity, and impulsivity but not oppositional or dissocial symptoms. Hyperechogenicity, defined as echogenic size above the 90th percentile in the control group, was present in 48% of ADHD patients. CONCLUSIONS Our findings indicate an increased vulnerability of the nigrostriatal system in ADHD. Transcranial sonography could be successfully used in the future to explore whether ADHD patients with distinct SN hyperechogenicity constitute a specific subgroup or whether hyperechogenicity relates functionally to differences in reward processing, learning, and motor function.