Brooks Applegate

Developmental change in attention-deficit hyperactivity disorder in boys: A four-year longitudinal study

One hundred six clinic-referred boys meeting criteria for DSM-III-R attention-deficit hyperactivity disorder (ADHD) (mean age 9.4 years) were assessed annually for 4 years using structured interviews of multiple informants. Hyperactivity—impulsivity symptoms declined with increasing age, but inattention symptoms did not. Rather, inattention declined only from the first to the second assessment and remained stable thereafter in boys of all ages. The rate of decline in hyperactivity—impulsivity symptoms was independent of the amount and type of treatment received. Boys who still met criteria for ADHD in Years 3 and 4 were significantly younger, more hyperactive—impulsive, and more likely to exhibit conduct disorder in Year 1 than boys who no longer met criteria in Years 3 and 4.

The structure of child and adolescent psychopathology: generating new hypotheses.

To begin to resolve conflicts among current competing taxonomies of child and adolescent psychopathology, the authors developed an interview covering the symptoms of anxiety, depression, inattention, and disruptive behavior used in the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994), the International Statistical Classification of Diseases and Related Health Problems (ICD-10; World Health Organization, 1992), and several implicit taxonomies. This interview will be used in the future to compare the internal and external validity of alternative taxonomies. To provide an informative framework for future hypothesis-testing studies, the authors used principal factor analysis to induce new testable hypotheses regarding the structure of this item pool in a representative sample of 1,358 children and adolescents ranging in age from 4 to 17 years. The resulting hypotheses differed from the DSM-IV, particularly in suggesting that some anxiety symptoms are part of the same syndrome as depression, whereas separation anxiety, fears, and compulsions constitute a separate anxiety dimension.

Validity of DSM-IV subtypes of conduct disorder based on age of onset

OBJECTIVE To present data from the DSM-IV field trials that led to the distinction between subtypes of conduct disorder (CD) that emerge in childhood or adolescence. In addition, data from a household sample were used to attempt to cross-validate these findings. METHOD Differences between youths who met criteria for the two subtypes of CD were examined in the field trials sample of 440 youths aged 4 through 17 years and in a household sample of 1,285 youths aged 9 through 17 years. RESULTS In both samples, there was a steep decline in aggression occurring around an age of onset of 10 years, but the number of nonaggressive behaviors was unrelated to the age of onset of CD. In the field trials sample, youths who met criteria for the adolescent-onset type were more likely to be girls, less likely to meet criteria for oppositional defiant disorder, and less likely to have a family history of antisocial behavior than the childhood-onset type, but these latter findings were not confirmed in the household sample. CONCLUSIONS The DSM-IV approach to subtyping CD distinguishes subgroups that differ markedly in level of physical aggression. The advantages of a developmental approach to subtyping are discussed.

Lower extremity blood flow and responses to occlusion ischemia differ in exercise-trained and sedentary tetraplegic persons

OBJECTIVE To test whether lower extremity blood flow and hyperemic responses to vascular occlusion differ among electrically stimulated exercise trained and sedentary tetraplegic persons and subjects without tetraplegia (control). DESIGN Blinded cross-sectional comparison, control group. SETTING Academic medical center. PARTICIPANTS Ten sedentary tetraplegic men, 10 tetraplegic persons previously habituated to electrically stimulated cycling exercise for 0.4 to 7 years, and 10 nondisabled controls. OUTCOME MEASURES Subjects underwent quantitative Doppler ultrasound examination of the common femoral artery (CFA). End-diastolic arterial images and arterial flow-velocity profiles obtained at rest and following five minutes of suprasystolic thigh occlusion were computer digitized for analysis of heart rate (HR), CFA peak systolic velocity (PSV), CFA cross-sectional area (CSA), flow velocity integral (FVI), and computed CFA inflow volume (IV). RESULTS No group main effects were observed for resting HR or FVI. At rest, trained tetraplegic men had 14.9% greater PSV, 29.8% larger CSA, and 51.3% greater IV (p values < .05) than sedentary tetraplegic subjects. Resting PSV and IV of the trained subjects did not differ from controls, although CSA was smaller than controls (p < .05). Following occlusion, PSV, CSA, and IV averaged 16.5%, 33.4%, and 65.1% greater for trained tetraplegics persons, respectively, than sedentary tetraplegic subjects (p values < .05). Only CSA differed between the control and the trained groups (p < .05). CONCLUSION Tetraplegic persons conditioned by electrically stimulated cycling have greater lower extremity blood flow and hyperemic responses to occlusion than do their sedentary counterparts.

Middle School Students' Mathematical Problem Solving: An Analysis of Think-Aloud Protocols.

Using a cognitive-metacognitive theoretical framework, this study examined the verbalizations of middle school students as they thought aloud while solving three mathematical word problems. Middle school subjects who had been identified as learning disabled, average achieving, and gifted were given demonstrations and practice in thinking aloud and were then instructed to solve one-step, two-step, and three-step word problems while thinking aloud. A priori categories were developed based on information-processing theory and a cognitive-metacognitive perspective of mathematical problem solving. Verbalizations were coded, and between-group and grade comparisons of the number of verbalizations within categories were conducted. The relationship between type of verbalization and overall performance was also analyzed. The findings support Ericcson and Simons (1980) view of concurrent verbalization as a technique for assessing cognitive processes and Swansons (1988) notion that students with learning disabilities may use a qualitatively different approach to problem solving than their nondisabled peers.

Relation of Age of Onset to the Type and Severity of Child and Adolescent Conduct Problems

In a cross-sectional household sample of 9-through 17-year-old youths from 4 U.S. communities, youths with earlier ages of onset of conduct problems engaged in more conduct problems than youths with later ages of onset when current age and gender were controlled. Specifically, youths with earlier ages of onset were more likely to engage in several types of physical aggression, frequent lying, theft, and vandalism and were less likely to engage in only truancy. There also was an inverse relation between age of onset and level of functional impairment, mental health service use, and meeting diagnostic criteria for conduct disorder, attention-deficit hyperactivity disorder, and oppositional defiant disorder. Within the limits of cross-sectional data, these results support the hypothesis that key aspects of the heterogeneity of conduct problems among youths are related to the age of onset of conduct problems.

Experimental Comparison of Inquiry and Direct Instruction in Science.

There are continuing educational and political debates about ‘inquiry’ versus ‘direct’ teaching of science. Traditional science instruction has been largely direct but in the US, recent national and state science education standards advocate inquiry throughout K‐12 education. While inquiry‐based instruction has the advantage of modelling aspects of the nature of real scientific inquiry, there is little unconfounded comparative research into the effectiveness and efficiency of the two instructional modes for developing science conceptual understanding. This research undertook a controlled experimental study comparing the efficacy of carefully designed inquiry instruction and equally carefully designed direct instruction in realistic science classroom situations at the middle school grades. The research design addressed common threats to validity. We report on the nature of the instructional units in each mode, research design, methods, classroom implementations, monitoring, assessments, analysis and project findings.

Psychometric Characteristics of a Measure of Emotional Dispositions Developed to Test a Developmental Propensity Model of Conduct Disorder

Lahey and Waldman proposed a developmental propensity model in which three dimensions of childrens emotional dispositions are hypothesized to transact with the environment to influence risk for conduct disorder, heterogeneity in conduct disorder, and comorbidity with other disorders. To prepare for future tests of this model, a new measure of these dispositions was tested. Exploratory factor analysis of potential items was conducted in a sample of 1,358 participants 4 to 17 years of age. Confirmatory factor analyses then confirmed the three dispositional dimensions in a second sample of 2,063 pairs of 6- to 17-year-old twins. Caretaker ratings of the dispositional dimensions were associated as predicted with symptoms of conduct disorder and other psychopathology. In a third sample, caretaker ratings of each disposition correlated uniquely with relevant observational measures of child behavior and unintentional injuries. These findings provide initial support for the new dispositional measure.

Comparison of MRI with EMG to study muscle activity associated with dynamic plantar flexion

This study compared magnetic resonance imaging (MRI) and surface electromyography (EMG) to evaluate the effect of knee angle upon plantar flexion activity in the triceps surae muscles [medial & lateral gastrocnemius (MG, LG) and the soleus (SOL)]. Two weight & height matched groups performed identical protocols, twelve (6M, 6F) in the MRI group, twelve (8M, 4F) in the EMG group. Subjects plantar flexed dynamically for 2 min at 25% of 1-repetition maximum voluntary contraction (1-RM). Exercise was performed with the knee extended (0 degrees flexion), flexed (90 degrees ), and partially flexed (45 degrees ). In the MRI group spin-echo images were acquired before and immediately following each exercise session. T(2) times, calculated at rest and after exercise by fitting the echoes to a monoexponential decay pattern with a least-squares algorithm, were compared with EMG data. In the EMG group a bipolar electrode was used to collect samples were from the MG, LG, SOL, and anterior tibialis (TA) during exercise at each knee angle, MRI also examined the peroneus (PER). At 0 degrees flexion MRI demonstrated a significant post-exercise T(2) increase in the MG (p < or = 0.001), LG (p < or = 0.001), and PER (p < or = 0.01), with no T(2) change in the SOL or TA. At 90 degrees flexion there was a significant T(2) increase in the SOL (p < or = 0.001) with no significant T(2) change in the MG, LG, PER, or TA. At 45 degrees T(2) increased significantly in the SOL (p < or = 0.001) and LG (p < or = 0.05), but not the MG, PER, or TA. EMG produced similar results with the exception that there was significant activity in the TA during the relaxation cycle of the 90 degrees protocol. We conclude that: 1) Soleus activity is measurable by MRI; and 2) MRI and EMG produce similar results from different physiological sources, and are therefore complementary tools for evaluating muscle activity.

Effects of acute inhalation of the bronchodilator, albuterol, on power output

This study was designed to examine the effects of acute inhalation of the bronchodilator, albuterol (Proventil, Schering Corp.), on high intensity power output. Fifteen healthy nonasthmatic subjects (eight male, seven female, 18-33 yr) performed four supramaximal 15-s rides on a bicycle ergometer. Rides were arranged in pairs with a 10-min rest interval. Each pair of rides was preceded by a 5-min warm-up. Sessions were separated by a minimum of 48 h. The study design was fully randomized and double blind. Ten minutes prior to each pair of rides subjects inhaled two metered doses (180 micrograms) of albuterol (A) or a placebo (P). Individual ANOVAs revealed a significant difference between the A and P treatment for peak power (A = 886.6 W, P = 858.3 W) and fatigue (A = 27.2%, P = 24.4%). Mean changes in FEF25-75% (A = 0.712, P = 0.040 l.s-1), FEV1.0 (A = 0.188, P = 0.007 l), and PEF (A = 0.573, P = -0.155 l.s-1) were also statistically significant; however, these changes did not correlate to the anaerobic performance changes. No significant differences were found between treatments for heart rate increases resulting from the power test (A = 56.73 bpm, P = 53.20 bpm). These results indicate an ergogenic effect of the bronchodilator on short-term power output independent of impact on respiratory smooth muscle, with no effect on cardiac response.