Biomedical subjects

Dirk L Knol

Publications and source records attributed to Dirk L Knol.

At least 19 recordsLinked to original sources

PubMed2007

Delineation of brain AVMs on MR-Angiography for the purpose of stereotactic radiosurgery.

PURPOSE: To assess the dosimetric consequences of brain arteriovenous malformation (bAVM) delineation on magnetic resonance angiography (MRA) for the purpose of stereotactic radiosurgery. METHODS AND MATERIALS: Three observers contoured a bAVM in 20 patients, using digital subtraction angiography (V(DSA)) and three-dimensional time-of-flight MRA (V(MRA)). Displacement between contours was calculated. Agreement and differences between observers and imaging modalities were assessed. A standardized treatment plan with dynamic conformal arcs was generated and dosimetric coverage of all contours and the volume of normal brain tissue within the high dose region was determined. RESULTS: The generalized reliability coefficient was "fair" for target volume (0.79), but "poor" for displacement (0.35). V(MRA) was larger than V(DSA) (5.0 vs. 4.0 mL, p = 0.001). No difference in displacement was found (2.8 vs. 2.5 mm, p = 0.156). Dosimetric coverage of V(MRA) was 62.9% (95% CI, 56.9-68.8) when V(DSA) was used as planning target volume, and coverage of V(DSA) was 83.5% (95% CI, 78.1-88.8) when V(MRA) was used for planning (p < 0.001). The mean volume of normal brain within the 80% isodose was larger when the bAVM was delineated on MRA (0.7 vs. 1.0 mL (p = 0.02) for targets < or =3 mL and 3.7 vs. 7.0 mL (p = 0.01) for targets >3 mL). CONCLUSIONS: Brain arteriovenous malformations delineated on MRA are larger and more randomly displaced. However, for bAVMs < or =3 mL, the difference in volume of normal brain tissue within the high-dose region does not seem to be clinically relevant. Therefore, MRA-images might be used as the sole imaging modality for the radiosurgical treatment of bAVMs < or =3 mL when the bAVM is located in a noneloquent position.

Humans↗

PubMed2007

Effect of multilevel botulinum toxin a and comprehensive rehabilitation on gait in cerebral palsy.

To evaluate the effect of multilevel botulinum toxin A and comprehensive rehabilitation on gait pattern, muscle length, and spasticity, a multicenter randomized trial was performed in 46 children with spastic cerebral palsy who walk with flexed knees. Their mean age was 8.0 years (range 4 to 11 years). They were randomly allocated to the intervention group (multilevel botulinum toxin A and comprehensive rehabilitation) or the control group (usual care). After 6 weeks, a significant treatment effect in the intervention group was observed on: improved knee extension during midstance and terminal swing (7 degrees and 5 degrees , P < 0.01, respectively); hip rotation during terminal swing (4 degrees , P = 0.02); gait score (1.7, P < 0.01); decreased spasticity in hamstrings (11 degrees , P < 0.01), gastrocnemius (6 degrees , P = 0.01), and soleus (5 degrees , P = 0.02); and increased muscle length in hamstrings (9 degrees , P < 0.01) and gastrocnemius (5 degrees , P < 0.01). The improved muscle length was maintained up to 24 weeks. This study demonstrated that multilevel botulinum toxin A and comprehensive rehabilitation improves knee extension during gait, increases muscle length, and decreases spasticity in injected muscles after 6 weeks in children who walk with flexed knees. Although the effect on muscle length was maintained after 24 weeks, the effect on gait and spasticity had disappeared.

Botulinum Toxins, Type A↗

PubMed2006

Minimally important change determined by a visual method integrating an anchor-based and a distribution-based approach.

BACKGROUND: Minimally important changes (MIC) in scores help interpret results from health status instruments. Various distribution-based and anchor-based approaches have been proposed to assess MIC. OBJECTIVES: To describe and apply a visual method, called the anchor-based MIC distribution method, which integrates both approaches. METHOD: Using an anchor, patients are categorized as persons with an important improvement, an important deterioration, or without important change. For these three groups the distribution of the change scores on the health status instrument are depicted in a graph. We present two cut-off points for an MIC: the ROC cut-off point and the 95% limit cut-off point. RESULTS: We illustrate our anchor-based MIC distribution method determining the MIC for the Pain Intensity Numerical Rating Scale in patients with low back pain, using two conceivable definitions of minimal important change on the anchor. The graph shows the distribution of the scores of the health status instrument for the relevant categories on the anchor, and also the consequences of choosing the ROC cut-off point or the 95% limit cut-off point. DISCUSSION: The anchor-based MIC distribution method provides a general framework, applicable to all kind of anchors. This method forces researchers to choose and justify their choice of an appropriate anchor and to define minimal importance on that anchor. The MIC is not an invariable characteristic of a measurement instrument, but may depend, among other things, on the perspective from which minimal importance is considered and the baseline values on the measurement instrument under study. A balance needs to be struck between the practicality of a single MIC value and the validity of a range of MIC values.

Health Status Indicators↗

PubMed2006

Cortisol moderates the relationship between testosterone and aggression in delinquent male adolescents.

BACKGROUND: In animals, strong evidence exists for an association between testosterone and aggression. In humans, and particularly in children and adolescents, findings have been less consistent. Previous research has suggested that this may partly be due to moderating effects of other factors, e.g., hormones. This study aims to investigate the moderating effect of cortisol on the relationship between testosterone and subtypes of aggression in delinquent male adolescents. METHODS: Participants were 103 boys (mean age 13.7) referred to a delinquency diversion program. Testosterone and cortisol levels were determined from saliva samples collected during resting conditions and related to self-report scores on overt and covert aggression. RESULTS: Linear regression analyses revealed a significant interaction between cortisol and testosterone in relation to overt aggression, with a significant positive relationship between testosterone and overt aggression in subjects with low cortisol levels but not in subjects with high cortisol levels. Using the same model for covert aggression, no significant effects of testosterone, cortisol, or testosterone x cortisol interaction were found. CONCLUSIONS: These results indicate a moderating effect of cortisol on the relationship between testosterone and overt aggression in delinquent male adolescents. Implications and directions for future research are discussed.

Adolescent↗

PubMed2006

Quality criteria were proposed for measurement properties of health status questionnaires.

OBJECTIVES: Recently, an increasing number of systematic reviews have been published in which the measurement properties of health status questionnaires are compared. For a meaningful comparison, quality criteria for measurement properties are needed. Our aim was to develop quality criteria for design, methods, and outcomes of studies on the development and evaluation of health status questionnaires. STUDY DESIGN AND SETTING: Quality criteria for content validity, internal consistency, criterion validity, construct validity, reproducibility, longitudinal validity, responsiveness, floor and ceiling effects, and interpretability were derived from existing guidelines and consensus within our research group. RESULTS: For each measurement property a criterion was defined for a positive, negative, or indeterminate rating, depending on the design, methods, and outcomes of the validation study. CONCLUSION: Our criteria make a substantial contribution toward defining explicit quality criteria for measurement properties of health status questionnaires. Our criteria can be used in systematic reviews of health status questionnaires, to detect shortcomings and gaps in knowledge of measurement properties, and to design validation studies. The future challenge will be to refine and complete the criteria and to reach broad consensus, especially on quality criteria for good measurement properties.

Evaluation Studies as Topic↗

PubMed2006

Minimal changes in health status questionnaires: distinction between minimally detectable change and minimally important change.

Changes in scores on health status questionnaires are difficult to interpret. Several methods to determine minimally important changes (MICs) have been proposed which can broadly be divided in distribution-based and anchor-based methods. Comparisons of these methods have led to insight into essential differences between these approaches. Some authors have tried to come to a uniform measure for the MIC, such as 0.5 standard deviation and the value of one standard error of measurement (SEM). Others have emphasized the diversity of MIC values, depending on the type of anchor, the definition of minimal importance on the anchor, and characteristics of the disease under study. A closer look makes clear that some distribution-based methods have been merely focused on minimally detectable changes. For assessing minimally important changes, anchor-based methods are preferred, as they include a definition of what is minimally important. Acknowledging the distinction between minimally detectable and minimally important changes is useful, not only to avoid confusion among MIC methods, but also to gain information on two important benchmarks on the scale of a health status measurement instrument. Appreciating the distinction, it becomes possible to judge whether the minimally detectable change of a measurement instrument is sufficiently small to detect minimally important changes.

Attitude to Health↗

PubMed2006

When to use agreement versus reliability measures.

BACKGROUND: Reproducibility concerns the degree to which repeated measurements provide similar results. Agreement parameters assess how close the results of the repeated measurements are, by estimating the measurement error in repeated measurements. Reliability parameters assess whether study objects, often persons, can be distinguished from each other, despite measurement errors. In that case, the measurement error is related to the variability between persons. Consequently, reliability parameters are highly dependent on the heterogeneity of the study sample, while the agreement parameters, based on measurement error, are more a pure characteristic of the measurement instrument. METHODS AND RESULTS: Using an example of an interrater study, in which different physical therapists measure the range of motion of the arm in patients with shoulder complaints, the differences and relationships between reliability and agreement parameters for continuous variables are illustrated. CONCLUSION: If the research question concerns the distinction of persons, reliability parameters are the most appropriate. But if the aim is to measure change in health status, which is often the case in clinical practice, parameters of agreement are preferred.

Humans↗

PubMed2006

Whole-brain T1 mapping in multiple sclerosis: global changes of normal-appearing gray and white matter.

PURPOSE: To prospectively investigate whether T1 changes in normal-appearing white matter (WM) and normal-appearing gray matter (GM) in multiple sclerosis (MS) are global or regional and their relationship to disease type. MATERIALS AND METHODS: The institutional ethics review board approved study; written informed consent was obtained. Whole-brain T1 maps were obtained in 67 patients with MS and 24 healthy control subjects with three-dimensional fast low-angle shot flip angle-array method, with correction for B(1) imperfections. Analysis of variance was performed on T1 histogram parameters of global normal-appearing WM and GM. Regional mean T1 values were analyzed with a multilevel approach. Multiple linear regression analysis was performed to investigate associations with clinical disability and overall atrophy. For patients, T2 lesion load was determined. RESULTS: T1 histograms of normal-appearing WM had significantly higher peak positions for patients with MS (792 msec +/- 36 in secondary progressive [SP] MS) than for control subjects (746 msec +/- 23) and were significantly broader and lower (all P < .001). Histograms for cortical normal-appearing GM were significantly shifted (peak positions, 1263 msec +/- 44 in control subjects and 1355 msec +/- 62 in patients with SP MS) (P < .001). Histogram peak positions were significantly higher in SP MS than in relapsing-remitting (RR) and primary progressive MS (P < .05). In SP disease, at least 31% of normal-appearing WM and 20% of cortical normal-appearing GM were affected. In MS, T1 was significantly elevated in all normal-appearing WM and cortical normal-appearing GM regions (all P < .01) but was elevated only in the thalamus in deep GM (P < .05). Cortical T1 histogram peak position was associated with clinical disability; T2 lesion load was not. CONCLUSION: Results suggest that a global disease process affects large parts of both normal-appearing WM and GM in MS and effects are worse for SP MS than for RR MS.

Adult↗

PubMed2006

Changes in the incidence of occupational disability as a result of back and neck pain in the Netherlands.

BACKGROUND: Back pain (including neck pain) is one of the most prevalent health problems for which physicians are consulted. Back pain can decrease the quality of life considerably during a great part of the lives of those who suffer from it. At the same time it has an enormous economic impact, mainly through sickness absence and long-term disability. The objective of this paper is to compare the incidence of occupational disability as a result of back and neck pain in 1980-1985 to 1999-2000 and to explain the findings. METHODS: A descriptive study was performed at population level of changes in incidence of occupational disability as a result of back and neck pain. Statistics from the National Institute of Social Insurance in the Netherlands are used to calculate age and gender specific incidence rates for back pain diagnoses based on the ICD-classification. Incidence rate ratios stratified according to gender and adjusted for age were calculated to indicate changes over time. RESULTS: The incidence of occupational disability as a result of back pain decreased significantly by 37% (95% CI 37%-38%) in men and with 21% (95% CI 20%-24%) in women, after adjustment for age. For overall occupational disability as a result of all diagnoses this was 18% (95% CI 18%-19%) and 34% (95% CI 33%-35%) respectively. Changes were not homogeneous over diagnostic subcategories and age groups. Spondylosis decreased most in men by 59% (95% CI 57%-61%). The incidence of non-specific back pain and neck pain increased most by 196% (95% CI 164%-215%). Post-laminectomy syndrome increased over all age categories both for men (85%, 95% CI 61%-113%) and women (113%, 95% CI 65%-179%). CONCLUSION: The decrease in occupational disability as a result of back pain was larger than the decrease in occupational disability over all diagnoses. However, time trends were not homogeneous over age-, nor over sex- nor back pain categories. Most of this decrease was due to general changes such as legal and economic changes. One of several additional explanations for a decrease is the changed view on management of back pain.

Adult↗

PubMed2006

Interobserver agreement on the radiological criteria of the International Panel on the diagnosis of multiple sclerosis.

We assessed the interobserver agreement on the radiological part of the International Panel (IP) criteria for the diagnosis of multiple sclerosis (MS), comprising the assessment of dissemination in space (DIS) and time (DIT) based exclusively on MRI. Four radiologists trained and four radiologists naive in the application of the IP criteria scored the fulfillment for DIS (i.e., > or =3 periventricular, > or =1 infratentorial, > or =1 juxtacortical, > or = 1 enhancing lesion or a total of > or =9 T2-weighted lesions) and DIT (presence of new or enhancing lesions at follow-up) in baseline and two follow-up scans from 20 patients suspected for having MS. The IP-trained radiologists agreed at least moderately on all assessments (kappa>0.40), whereas the IP-naive radiologists showed fair agreement (kappa<0.40) on five of 16 assessments. In the final conclusion on DIS and DIT, the IP-trained radiologists agreed substantially on both items (kappa=0.62 and kappa=0.60, respectively) compared with a fair agreement on DIS (kappa=0.29) and moderate agreement on DIT (kappa=0.52) among the IP-naive radiologists. Given the poor interobserver agreement among IP-naive observers, the new IP criteria for MS require additional training and should perhaps be simplified.

Adolescent↗

PubMed2006

The effectiveness of high-intensity versus low-intensity back schools in an occupational setting: a pragmatic randomized controlled trial.

STUDY DESIGN: Randomized controlled trial. OBJECTIVES: To compare high- and low-intensity back schools with usual care in occupational health care. SUMMARY OF BACKGROUND DATA: The content and intensity of back schools vary widely and the methodologic quality of randomized controlled trials is generally weak. Until now, no back school has proven to be superior for workers sick-listed because of subacute nonspecific low back pain. METHODS: Workers (n = 299) sick-listed for a period of 3 to 6 weeks because of nonspecific low back pain were recruited by the occupational physician and randomly assigned to a high-intensity back school, a low-intensity back school, or care as usual. Outcome measures were days until return to work, total days of sick-leave, pain, functional status, kinesiophobia, and perceived recovery and were assessed at baseline and at 3 and 6 months of follow-up. Principal analyses were performed according to the intention-to-treat principle. RESULTS: We randomly allocated 299 workers. Workers in the low-intensity back school returned to work faster compared with usual care and the high-intensity back school, with hazard ratios of 1.4 (P = 0.06) and 1.3 (P = 0.09), respectively. The comparison between high-intensity back school and usual care resulted in a hazard ratio of 1.0 (P = 0.83). The median number of sick-leave days was 68, 75, and 85 in the low-intensity back school, usual care, and high-intensity back school, respectively. Beneficial effects on functional status and kinesiophobia were found at 3 months in favor of the low-intensity back school. No substantial differences on pain and perceived recovery were found between groups. CONCLUSIONS: The low-intensity back school was most effective in reducing work absence, functional disability, and kinesiophobia, and more workers in this group scored a higher perceived recovery during the 6-month follow-up.

Adult↗

PubMed2006

Altered diffusion tensor in multiple sclerosis normal-appearing brain tissue: cortical diffusion changes seem related to clinical deterioration.

PURPOSE: To investigate normal-appearing white (NAWM) and cortical gray (NAGM) matter separately in multiple sclerosis (MS) in vivo using diffusion tensor imaging (DTI). MATERIALS AND METHODS: In 64 MS patients (12 primary progressive [PP], 38 relapsing remitting [RR], 14 secondary progressive [SP]) and 20 healthy controls, whole-brain apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were acquired. A stimulated echo acquisition mode (STEAM) DTI sequence was used with minimal geometrical distortion in comparison to echo-planar imaging (EPI). NAWM and NAGM were identified using conventional magnetic resonance (MR) images, allowing a cautious assessment of FA in cortex. RESULTS: Histogram analyses showed significant global FA decreases and ADC increases in MS NAWM compared to control WM. MS cortical NAGM had no significant global ADC increase, but FA was decreased significantly. In regional analyses, nearly all NAWM regions-of-interest (ROIs) had significantly increased ADC compared to controls, but FA was not changed. In nearly all cortical NAGM ROIs, ADC was significantly increased and FA significantly reduced. In multiple linear regression analyses in RR/SPMS patients, NAGM-ADC histogram peak height was associated more strongly with clinical disability than T2 lesion load. CONCLUSION: Tissue damage occurs in both NAWM and cortical NAGM. The cortical damage appears to have more clinical impact than T2 lesions.

Adult↗

PubMed2006

Workers' beliefs and expectations affect return to work over 12 months.

BACKGROUND: Successful management of workers on sick leave due to low back pain depends on the identification by the occupational physician of modifiable prognostic factors in the early phase of sick-leave. The prognostic value of factors which influence the course of low back pain and return to work in occupational health care is unclear. METHODS: Secondary data analysis in a cohort of 299 workers on sick leave between 3 and 6 weeks due to low back pain was applied. We investigated the association of a broad set of prognostic indicators related to characteristics of worker, job, low back pain and psychosocial issues on return to work lasting at least 4 weeks (lasting-RTW) and minimally 1 day of first return to work (first-RTW). Relationships were studied using Cox regression analysis and covered a follow-up period of 12 months. The explained variation of the models was also calculated. RESULTS: The median time to return to work using lasting-RTW and first-RTW was 76 and 71 days respectively. In addition to individual analysis of potential predictive factors a backward selection procedure resulted in the following multivariable model: self-predicted timing of return to work, pain intensity, job satisfaction, social support, pain radiation, expectations of treatment succes of the occupational physician. Similar results were found for first-RTW. The explained variance of the multivariate model of lasting-RTW was 18%. CONCLUSIONS: Factors concerning the expectations and beliefs of the worker affected the RTW process. Knowledge of these factors by the occupational physician in the early phase of low back pain and sick-leave may contribute to solutions to promote return to work.

Adolescent↗

PubMed2006

The combined effect of lower-limb multilevel botulinum toxin type a and comprehensive rehabilitation on mobility in children with cerebral palsy: a randomized clinical trial.

OBJECTIVE: To evaluate the combined effect on mobility of treatment with multilevel botulinum toxin type A (BTX-A) and comprehensive rehabilitation in children with cerebral palsy (CP). DESIGN: Randomized clinical trial using a multiple baseline design. The intervention group was treated 6 weeks after randomization. The control group was treated after a longer period of 18 to 30 weeks. Repeated measurements in both groups were continued throughout the process, before and up to 48 weeks after treatment. SETTING: Four departments of rehabilitation medicine in The Netherlands. PARTICIPANTS: Forty-six children with spastic CP (mean age +/- standard deviation, 8.0+/-2.1y). INTERVENTION: The intervention group (n=23) was treated with multilevel BTX-A and comprehensive rehabilitation. Control group subjects (n=23) continued with their usual physical therapy (PT) for 18 to 30 weeks, and then also received multilevel BTX-A and comprehensive rehabilitation. MAIN OUTCOME MEASURES: The primary outcome measure was the Gross Motor Function Measure (GMFM-66); the secondary measures were problem score and energy cost. RESULTS: The treatment effect during the first 24 weeks of follow-up in the intervention group was compared with the effect of usual PT in the control group. Treatment with multilevel BTX-A and comprehensive rehabilitation provided a significantly greater improvement at 12 and 24 weeks in both the GMFM-66 (2.1 points, P=.02; and 3.5 points, P<.01, respectively) and problem score (1.8 and 1.7 points, P<.001, respectively) compared with usual PT. No difference was found in energy cost. Before-after analysis of the total group (n=46) showed a significant long-term improvement (48wk) on all outcome measures. CONCLUSIONS: Treatment with multilevel BTX-A and comprehensive rehabilitation significantly improves mobility as measured by the GMFM-66 and problem score in children with CP.

Botulinum Toxins, Type A↗

PubMed2006

Activities and participation of 9- to 13-year-old children with cerebral palsy.

OBJECTIVE: To describe the activities and participation of children with cerebral palsy and to examine the relationship with personal factors and disease characteristics. DESIGN: Cross-sectional study. SETTING: Department of Rehabilitation Medicine of a University Medical Center in The Netherlands. SUBJECTS: One hundred and ten children: 70 boys, 40 girls, mean (SD) age 11 years and 3 months (20 months). OUTCOME MEASURES: Activities and participation, described in the domains of mobility, self-care, domestic life, social life and communication, measured with the Gross Motor Function Measure, the Pediatric Evaluation of Disability Inventory and the Vineland Adaptive Behavior Scales. RESULTS: Multiple linear regression models showed that the Gross Motor Function Classification System (GMFCS) was strongly associated with mobility (explained variance 87-92%), self-care and domestic life. Apart from the GMFCS, cognitive impairment and limb distribution were less important but also significantly associated with self-care and domestic life (explained variance 65-81%). Cognitive impairment and epilepsy were the most important factors associated with social life and communication (explained variance 54-75%). CONCLUSION: Activities and participation can, to a large extent, be explained by only a few associated factors.

Activities of Daily Living↗

PubMed2005

Raloxifene treatment enhances brain activation during recognition of familiar items: a pharmacological fMRI study in healthy elderly males.

Raloxifene is a selective estrogen receptor modulator that may delay the onset of mild cognitive impairment in elderly women. Effects of raloxifene treatment on mental performance in males remain to be investigated. In a previous functional magnetic resonance imaging (fMRI) study, we showed that raloxifene treatment enhanced brain activation in elderly males during encoding of new information (faces) into memory. The current study used fMRI in the same group of subjects to screen for effects of raloxifene treatment on brain function during face recognition. Healthy elderly males (n=28; mean age 63.6 years, SD 2.4) were scanned at baseline and after 3 months of treatment with either raloxifene 120 mg (n=14) or placebo (n=14) in a randomized, double-blind, placebo-controlled study design. Functional data were analyzed in an event-related fashion with respect to correct hits and correct rejections using FSL software. Performance data were analyzed with respect to recognition accuracy, latency, and response bias. Functional effects of treatment were found on brain activation related to correct hits only. When compared to placebo treatment, raloxifene treatment enhanced brain activation in the left posterior parahippocampal area (Z=3.9) and right inferior prefrontal cortex (Z=3.5). Recognition accuracy scores remained stable in the raloxifene group, whereas the placebo group showed a small but significant decrease in accuracy scores (p=0.02). No significant effects were found on response bias or latency. In conclusion, raloxifene treatment affects brain function during memory performance in a way that may reflect increased arousal during initial encoding, with downstream effects on brain function during retrieval of information. Behaviorally, such neurofunctional effects may actively block decreased memory performance as a result of context-dependency. The validity of these predictions can be tested in large-scale clinical trials.

Aged↗

PubMed2005

Prognostic factors for low back pain in patients referred for physiotherapy: comparing outcomes and varying modeling techniques.

STUDY DESIGN: Data were derived from a randomized controlled trial on the (cost-) effectiveness of the implementation of the clinical guidelines on physiotherapy for low back pain in primary care. OBJECTIVES: To describe the course of low back pain in patients who are referred to physiotherapy, to identify clinically important prognostic factors on different outcomes, and to evaluate the influence of different statistical techniques in developing a prognostic model. SUMMARY OF BACKGROUND DATA: Several studies have aimed to identify prognostic factors for low back pain in primary care. These studies focused on different outcome measures and used various statistical techniques. METHODS: Primary outcomes were perceived recovery, improvement in pain, improvement in functioning, and presence of disabling low back pain at 3 and 12 months follow-up. Multivariate logistic regression analyses were performed for each outcome variable. Two cut-off points were used to determine significance with respect to the univariate analysis, and two selection methods were used to build the final multivariate models. The resulting prognostic models were compared. RESULTS: A total of 500 patients were included. Pain and disability reduced considerably in the first 3 months, but further reduction was only modest. Prognostic factors varied for different outcomes, but the duration of the current episode was included in all models generated. Varying the statistical techniques also resulted in a different prognostic model with some change to the amount of variance explained. CONCLUSIONS: A substantial proportion of patients still experienced some pain and disability at 12 months follow-up. The most stable predictor of prognosis in low back pain was the duration of the current episode. The choice of statistical method influenced the final model; however, changes in the explained variance were small.

Adult↗

PubMed2005

Low basal salivary cortisol is associated with teacher-reported symptoms of conduct disorder.

Cortisol has been implicated in psychobiological explanations of antisocial behavior. This study measured basal salivary cortisol in a sample of 25 children (age range 6 to 12 years) selected to vary in levels of antisocial behavior. Regression analyses were used to predict cortisol concentrations from parent- and teacher-reported symptoms. Parent-reported symptoms did not predict basal cortisol. Teacher-reported conduct disorder (CD) symptoms explained 38% of the variance in the cortisol concentrations, with high symptom severity associated with low cortisol. When a distinction was made between aggressive and non-aggressive CD symptoms, aggressive CD symptoms were more clearly related to low cortisol than non-aggressive CD symptoms. In contrast to previous research, no evidence was found for a mediating role of anxiety symptoms in the relationship between CD and cortisol. The results support biologically based models of antisocial behavior in children that involve reduced autonomic activity.

Adolescent↗