Subtyping social anxiety in youth.

Few empirical studies have examined subtypes of social anxiety disorder (SAD) in youth, and limited consensus resides on the nature of potential subtypes. Identifying subtypes, based on both fear and avoidance patterns, can help improve assessment and treatment of SAD. Subtypes of fear and avoidance were examined in a sample comprising 131 youth (age 8-15 years) diagnosed with SAD using the Anxiety Disorders Interview Schedule for children and parents (ADIS-C/P). Exploratory factor analysis of fear responses revealed three factors, defining fear subtypes linked to: (1) performance, (2) observation, and (3) interaction situations, respectively. Exploratory factor analysis of avoidance responses showed these were best represented by one avoidance factor. Few youth qualified exclusively for either of the fear subtypes, thus calling into question the clinical utility of these subtypes. Nevertheless, the findings indicate distinct contributions of fear and avoidance in SAD presentation. This finding might help clinicians target and improve treatment of the disorder.

Between session reproducibility and between subject variability of diffusion MR and tractography measures.

As diffusion tractography is increasingly used to generate quantitative measures to address clinical questions, it is important to characterise the inter-session reproducibility and inter-subject variability of these measures. Here, we assess the reproducibility and variability of diffusion tractography measures using diffusion data from 8 subjects scanned 3 times. We used probabilistic tractography to define the cingulum bundle, pyramidal tracts, optic radiations and genu of the corpus callosum in each individual data set using three different methods of seed definition. Measures of mean fractional anisotropy (FA) and mean diffusivity (MD) along the tracts were more reproducible than measures of tract volume. Further, tracts defined using a two region of interest (ROI) approach were more reproducible than those defined using manually placed seed masks alone. For mean FA taken from tracts defined using the two ROI approach, inter-session coefficients of variation (CV) were all below 5% and inter-subject CVs were below 10%; for mean MD inter-session, CVs were all below 3% and inter-subject CVs were below 8%. We use the variability measures found here to calculate the sample sizes required to detect changes in FA, MD or tract volume of a given size, either between groups of subjects or within subjects over time. Finally, we compare tractography results using 60 diffusion encoding directions to those found using a subset of 12 directions; the number of diffusion directions did not have a significant effect on reproducibility, but tracts derived using fewer directions were consistently smaller than those derived using 60 direction data. We suggest that 12 direction data are sufficient for reproducibly defining the core of large bundles but may be less sensitive to smaller pathways.

Behaviour problems in children with dyslexia.

The association between behaviour problems and dyslexia was assessed in a population sample of 10- to 12-year-old children. Twenty-five dyslexic children and a matched control group were recruited through a screening in primary schools in the city of Bergen, Norway. For the assessment of behaviour problems the Child Behavior Checklist (CBCL), Teacher Self Report (TRF), and Youth Self Report (YSR) were filled out by parents, teachers, and children, respectively. Information on health and developmental factors were obtained from parents on a separate questionnaire designed for the study. The dyslexic group had significantly more behaviour problems than the control group according to both the CBCL and the TRF. On the YSR there was no significant difference between the groups. Dyslexic children had higher CBCL and TRF scores on the Total Behaviour Problem scale, the Internalizing and Externalizing subdomains, and the Attention problem subscale. The groups differed in social background, prenatal risk factors, birth weight, preschool language problems, and IQ, but these variables showed no relationship to the level of behaviour problems in the present sample. We conclude that pre-adolescent dyslexic children show a wide range of behaviour problems that cannot be attributed to social or developmental background variables.

Planum temporale, planum parietale and dichotic listening in dyslexia.

A reduction or reversal of the normal leftward asymmetry of the planum temporale (PT) has been claimed to be typical of dyslexia, although some recent studies have challenged this view. In a population-based study of 20 right-handed dyslexic boys and 20 matched controls, we have measured the PT and the adjacent planum parietale (PP) region in sagittal magnetic resonance images. For the PT, mean left and right areas and asymmetry coefficients were compared. Since a PP area often could not be identified in one or both hemispheres, a qualitative comparison was used for this region. The total planar area (sum of PT and PP) was also compared between the two groups. A dichotic listening (DL) test with consonant-vowel syllables was administered to assess functional asymmetry of language. The results showed a mean leftward PT asymmetry in both the dyslexic and the control group, with no significant difference for the degree of PT asymmetry. Planned comparisons revealed however, a trend towards smaller left PT in the dyslexic group. In control children, but not in the dyslexic children, a significant correlation between PT asymmetry and reading was observed. A mean leftward asymmetry was also found for the total planar area, with no difference between the groups for the degree of asymmetry. Significantly fewer dyslexic children than control children showed a rightward asymmetry for the PP region. Both groups showed a normal right ear advantage on the DL task, with no significant difference for DL asymmetry. No significant correlation was observed between PT asymmetry and DL asymmetry. The present population-based study adds to recent reports of normal PT asymmetry in dyslexia, but indicates that subtle morphological abnormalities in the left planar area may be present in this condition.

Central auditory processing, MRI morphometry and brain laterality: applications to dyslexia.

We review data from our laboratory related to a view of dyslexia as a biological disorder, or deficit, caused by both structural and functional brain abnormalities. The review is focused on central auditory processing in dyslexia, and the possibility that impairments in the auditory or acoustic features of the phonological code may be at the heart of the impairments seen in dyslexia. Three methodological approaches by which to investigate central auditory processing deficits are outlined: dichotic listening (DL) to consonant-vowel syllables; magnetic resonance imaging (MRI), and the use of event-related potentials (ERPs). Consonant-vowel syllable DL is a technique for probing the functional status of phonological processing areas in the superior temporal gyrus, particularly in the left hemisphere. MRI is a corresponding structural, or morphological, measure of anatomical abnormalities in the same brain region, particularly covering the planum temporale area. The ERP technique, and particularly the mismatch negativity (MMN) component, reveals cortical dysfunctions in sensory processing and memory related to basic acoustic events. For all three approaches, the dyslexic children were seen to differ from their control counterparts, including absence of modulation of the right ear advantage (REA), in DL through shifting of attention, smaller left-sided planum temporale asymmetry, and prolonged latency in the MMN ERP complex, particularly in the time-deviant stimulus condition.

Maturity-onset diabetes of the young. Studies in a Norwegian family.

A Norwegian family showed 20 cases of verified or suspected diabetes in 5 generations, 13 being females and 7 males. In 12 patients the diagnosis was established at 26 years of age or earlier. Fourteen patients were definitely non-insulin-dependent. A high frequency of severe diabetic ophthalmopathy was noted, five patients were blind, two had proliferative retinopathy, and one simplex retinopathy and cataract. Five patients from the last 3 generations were islet cell antibody negative and C-peptide positive. In selected patients the serum insulin response to oral glucose was markedly reduced. HLA determinations in these patients showed absence of DR3 and DR4, and presence of DR2. The inheritance of diabetes in this family is compatible with an autosomal, dominant trait, and the majority of cases fulfilled the criteria of maturity-onset diabetes of the young. The high frequency of severe ophthalmopathy underscores that this disease may have an unfavourable evolution.

Metabolic responses to physical training in young insulin-dependent diabetics.

Insulin-dependent (type 1) diabetics, aged 14-17 years, were studied according to two protocols. During a 6-month training period of moderate intensity (six participants) the aerobic work capacity and the erythrocyte insulin binding increased by 19% and 28%, respectively. Glycosylated haemoglobin (HbA1) was not significantly reduced. A 2-week intensive physical training program (10 participants) was associated with a 50% decrease of blood glucose values, which did not last beyond the training period. Plasma ketone bodies were markedly reduced. We conclude that young type 1 diabetics may participate in strenuous, short-term physical training. The improved aerobic work capacity and increased cellular insulin binding observed during training of moderate intensity is of potential benefit in the long-term management of the patients.

Responses of plasma adenosine 3',5'-monophosphate, blood glucose and plasma insulin to glucagon in humans.

The effect of glucagon on plasma cyclic AMP (cAMP), insulin and blood glucose was examined in normal adult subjects. After an i.v. injection of glucagon there was a rapid, dose-dependent increase of plasma cAMP as well as insulin and blood glucose. Multiple injection of glucagon to the same subject with 60 min intervals gave almost identical responses of plasma cAMP and blood glucose, whereas the insulin response tended to decrease with time. Dose-dependent increases of plasma cAMP, insulin and blood glucose were also seen during a continuous i.v. infusion of glucagon. With the lowest doses of glucagon the blood glucose and plasma insulin concentrations were increased without any change of plasma cAMP. Plasma cAMP, insulin and blood glucose declined prior to the termination of glucagon infusion. During an endogenous hyperglucagonaemia, induced by alanine injection, there was no discernible change of plasma cAMP. We conclude that the early events of glucagon action may be studied in vivo by monitoring plasma cAMP. However, variations of plasma glucagon within the physiological range are not accompanied by measurable changes of cAMP in the peripheral circulation.