Cardiopulmonary exercise testing (CPET) modalities, treadmill (TM), and cycle ergometer (CE), influence maximal gas exchange and heart rate (HR) responses. Little is known regarding CPET modality ...effect on submaximal biomarkers during childhood and adolescence. Ninety‐four healthy participants (7–34 y.o., 53% female) performed TM and CE CPET to address two major gaps: (1) the effect of modality on submaximal CPET biomarkers, and (2) estimation of work rate in TM CPET. Breath‐by‐breath gas exchange enabled calculation of linear regression slopes such as V˙O2/ΔHR and ΔV˙E/ΔV˙CO2. Lean body mass (LBM) was measured with dual X‐ray absorptiometry. We tested a novel TM CPET estimate of work rate based on TM velocity2, incline, and body mass (VIM). Like the linear relationship between V˙O2 and work rate in CE CPET, V˙O2 increased linearly with TM VIM. TM ΔV˙O2/ΔHR was highly correlated with CE (r = 0.92), and each increased substantially with LBM (P < 0.0001 for TM and CE). ΔV˙O2/ΔHR was to a small (~8.7%) but significant extent larger in TM (1.6 mL/min/beat, P = 0.04). In contrast, TM and CE ΔV˙E/ΔV˙CO2 decreased significantly with LBM, supporting earlier observations from CE CPET. For both CE and TM, males had significantly higher ΔV˙O2/ΔHR but lower ΔV˙E/ΔV˙CO2 than females. Novel TM CPET biomarkers such as ΔVIM/ΔHR and ∆V˙O2/ΔVIM paralleled effects of LBM observed in CE CPET. TM and CE CPET submaximal biomarkers are not interchangeable, but similarly reflect maturation during critical periods. CPET analysis that utilizes data actually measured (rather than estimated) may improve the clinical value of TM and CE CPET.
Treadmill (TM) and cycle ergometer (CE) CPET submaximal biomarkers are not interchangeable, but similarly reflect maturation during critical periods. CPET analysis that utilizes data actually measured (in a novel way) may improve the clinical value of TM and CE CPET.
Background
Inconsistent findings exist regarding long‐term substance use (SU) risk for children diagnosed with attention‐deficit/hyperactivity disorder (ADHD). The observational follow‐up of the ...Multimodal Treatment Study of Children with ADHD (MTA) provides an opportunity to assess long‐term outcomes in a large, diverse sample.
Methods
Five hundred forty‐seven children, mean age 8.5, diagnosed with DSM‐IV combined‐type ADHD and 258 classmates without ADHD (local normative comparison group; LNCG) completed the Substance Use Questionnaire up to eight times from mean age 10 to mean age 25.
Results
In adulthood, weekly marijuana use (32.8% ADHD vs. 21.3% LNCG) and daily cigarette smoking (35.9% vs. 17.5%) were more prevalent in the ADHD group than the LNCG. The cumulative record also revealed more early substance users in adolescence for ADHD (57.9%) than LNCG (41.9%), including younger first use of alcohol, cigarettes, marijuana, and illicit drugs. Alcohol and nonmarijuana illicit drug use escalated slightly faster in the ADHD group in early adolescence. Early SU predicted quicker SU escalation and more SU in adulthood for both groups.
Conclusions
Frequent SU for young adults with childhood ADHD is accompanied by greater initial exposure at a young age and slightly faster progression. Early SU prevention and screening is critical before escalation to intractable levels.
Heart Rate (HR) is widely used for erobic exercise intensity prescriptions and/or studies of exercise training. It is often assumed that exercising at a given HR results in similar physiological ...response, regardless of exercise modality. This study aimed to gauge cellular immune mobilization to submaximal exercise at a given target HR on a cycle ergometer (CE) and treadmill (TM). Thirteen healthy male adults (23.2 ± 3.5 y.o) completed 4 laboratory visits. Participants performed two graded exercise tests to exhaustion on CE and TM and two 30‐min constant exercise challenges at 70% HR reserve on CE or TM in random order. Rating of Perceived Exertion (RPE) was recorded every 5 min, and blood was drawn before and after exercise to measure leukocytes subpopulation levels, lactate, and IL‐6. HR was successfully “clamped” during the exercise in CE and TM (CE 156.7 ± 1.1; TM 159.3 ± 1.6 bpm). Cycling was perceived as more strenuous than running and was accompanied by a greater increase in lactate post‐exercise (p < 0.0001; 6.2 ± 0.3 vs. 2.9 ± 0.3 mmol/L). IL‐6 and leukocytes subpopulations were significantly elevated post‐exercise (p < 0.003) with no difference between exercise modalities (monocytes; CE 57.6% TM 61.2%, granulocytes; CE 41.37%, TM 50.1%, lymphocytes; CE 91.03%, TM 78.8%). The findings revealed that HR is not sufficient in and of itself to fully assess the metabolic stress associated with a given exercise modality. However, despite different metabolic and subjective stress, the IL‐6 and leukocyte counts relative changes were similar in the two modalities.
Highlights
These findings provide valuable insights into the leukocytes and lactate responses to cycling and running at the same target heart rate. The study further elaborates on the shared patterns and distinctions in physiological and metabolic responses and their implications for designing targeted training programs.
At the same target heart rate, running resulted in significantly lower lactate levels and subjective rate of perceived exertion (RPE) while yielding higher VO2 levels compared to cycling.
Leukocytes and IL‐6 increases post‐exercise were not different between running and cycling, indicating that they did not reflect the distinct metabolic and subjective perceived loads associated with cycling and running.
Since heart rate in and of itself is not sufficient to fully characterize the metabolic stress induced by a specific exercise modality, it is important to consider the modality of exercise when prescribing training programs for improving cardiovascular fitness or achieving target energy expenditure through heart rate monitoring.
Abstract
Introduction
Aerobic fitness facilitates brain synaptic plasticity, which influences global and local sleep expression. While it is known that sleep patterns/behavior and non-rapid eye ...movement (NREM) sleep slow wave activity (SWA) tracks brain maturation, little is known about how aerobic fitness and sleep interact during development in youth. The aim of this pilot was to characterize relationships among aerobic fitness, measures of global/local sleep expression, and habitual sleep patterns in children and adolescents. We hypothesized that greater aerobic fitness would be associated with better sleep quality, indicated by increased SWA.
Methods
20 adolescents (mean age=14.6±2.3 years old, range 11-17, 11 females) were evaluated for AF (peak VO2 assessed by ramp-type progressive cycle ergometry in the laboratory), habitual sleep duration and efficiency (continuous 7-14 day actigraphy with sleep diary), and topographic patterns of spectral power in slow wave, theta, and sleep spindle frequency ranges in non-rapid eye movement (NREM) sleep using overnight polysomnography with high-density electroencephalography (hdEEG, 128 channels).
Results
Significant relationships were observed between peak VO2 and habitual bedtime (r=-0.604, p=0.013) and wake-up time (r=-0.644, p=0.007), with greater fitness associated with an earlier sleep schedule (going to bed and waking up earlier). Peak VO2 was a significant predictor of slow oscillations (0.5-1Hz, p=0.018) and theta activity (4.5-7.5Hz, p=0.002) over anterior frontal and central derivations (p<0.001 and p=0.001, respectively) after adjusting for sex and pubertal development stage. Similar associations were detected for fast sleep spindle activity (13-16Hz, p=0.006), which was greater over temporo-parietal derivations.
Conclusion
Greater AF was associated with earlier habitual sleep times and with enhanced expression of developmentally-relevant sleep oscillations during NREM sleep. These data suggest that AF may 1) minimize the behavioral sleep delay commonly seen during adolescence, and 2) impact topographically-specific features of sleep physiology known to mechanistically support neuroplasticity and cognitive processes which are dependent on prefrontal cortex and hippocampal function in adolescents and adults.
Support (if any)
NCATS grant #UL1TR001414 & PERC Systems Biology Fund
Abstract
Introduction
Aerobic fitness facilitates brain synaptic plasticity, which influences global and local sleep expression. While it is known that sleep patterns/behavior and non-rapid eye ...movement (NREM) sleep slow wave activity (SWA) tracks brain maturation, little is known about how aerobic fitness and sleep interact during development in youth. The aim of this pilot was to characterize relationships among aerobic fitness, measures of global/local sleep expression, and habitual sleep patterns in children and adolescents. We hypothesized that greater aerobic fitness would be associated with better sleep quality, indicated by increased SWA.
Methods
20 adolescents (mean age=14.6±2.3 years old, range 11-17, 11 females) were evaluated for AF (peak VO2 assessed by ramp-type progressive cycle ergometry in the laboratory), habitual sleep duration and efficiency (continuous 7-14 day actigraphy with sleep diary), and topographic patterns of spectral power in slow wave, theta, and sleep spindle frequency ranges in non-rapid eye movement (NREM) sleep using overnight polysomnography with high-density electroencephalography (hdEEG, 128 channels).
Results
Significant relationships were observed between peak VO2 and habitual bedtime (r=-0.604, p=0.013) and wake-up time (r=-0.644, p=0.007), with greater fitness associated with an earlier sleep schedule (going to bed and waking up earlier). Peak VO2 was a significant predictor of slow oscillations (0.5-1Hz, p=0.018) and theta activity (4.5-7.5Hz, p=0.002) over anterior frontal and central derivations (p<0.001 and p=0.001, respectively) after adjusting for sex and pubertal development stage. Similar associations were detected for fast sleep spindle activity (13-16Hz, p=0.006), which was greater over temporo-parietal derivations.
Conclusion
Greater AF was associated with earlier habitual sleep times and with enhanced expression of developmentally-relevant sleep oscillations during NREM sleep. These data suggest that AF may 1) minimize the behavioral sleep delay commonly seen during adolescence, and 2) impact topographically-specific features of sleep physiology known to mechanistically support neuroplasticity and cognitive processes which are dependent on prefrontal cortex and hippocampal function in adolescents and adults.
Support (if any)
NCATS grant #UL1TR001414 & PERC Systems Biology Fund
Objective
Longitudinal studies of children diagnosed with ADHD report widely ranging ADHD persistence rates in adulthood (5–75%). This study documents how information source (parent vs. self‐report), ...method (rating scale vs. interview), and symptom threshold (DSM vs. norm‐based) influence reported ADHD persistence rates in adulthood.
Method
Five hundred seventy‐nine children were diagnosed with DSM‐IV ADHD‐Combined Type at baseline (ages 7.0–9.9 years) 289 classmates served as a local normative comparison group (LNCG), 476 and 241 of whom respectively were evaluated in adulthood (Mean Age = 24.7). Parent and self‐reports of symptoms and impairment on rating scales and structured interviews were used to investigate ADHD persistence in adulthood.
Results
Persistence rates were higher when using parent rather than self‐reports, structured interviews rather than rating scales (for self‐report but not parent report), and a norm‐based (NB) threshold of 4 symptoms rather than DSM criteria. Receiver‐Operating Characteristics (ROC) analyses revealed that sensitivity and specificity were optimized by combining parent and self‐reports on a rating scale and applying a NB threshold.
Conclusion
The interview format optimizes young adult self‐reporting when parent reports are not available. However, the combination of parent and self‐reports from rating scales, using an ‘or’ rule and a NB threshold optimized the balance between sensitivity and specificity. With this definition, 60% of the ADHD group demonstrated symptom persistence and 41% met both symptom and impairment criteria in adulthood.
Read the Commentary on this article at doi: 10.1111/jcpp.12758
Podcast link
Adolescents and young adults without childhood attention deficit hyperactivity disorder (ADHD) often present to clinics seeking stimulant medication for late-onset ADHD symptoms. Recent birth-cohort ...studies support the notion of late-onset ADHD, but these investigations are limited by relying on screening instruments to assess ADHD, not considering alternative causes of symptoms, or failing to obtain complete psychiatric histories. The authors address these limitations by examining psychiatric assessments administered longitudinally to the local normative comparison group of the Multimodal Treatment Study of ADHD.
Individuals without childhood ADHD (N=239) were administered eight assessments from comparison baseline (mean age=9.89 years) to young adulthood (mean age=24.40 years). Diagnostic procedures utilized parent, teacher, and self-reports of ADHD symptoms, impairment, substance use, and other mental disorders, with consideration of symptom context and timing.
Approximately 95% of individuals who initially screened positive on symptom checklists were excluded from late-onset ADHD diagnosis. Among individuals with impairing late-onset ADHD symptoms, the most common reason for diagnostic exclusion was symptoms or impairment occurring exclusively in the context of heavy substance use. Most late-onset cases displayed onset in adolescence and an adolescence-limited presentation. There was no evidence for adult-onset ADHD independent of a complex psychiatric history.
Individuals seeking treatment for late-onset ADHD may be valid cases; however, more commonly, symptoms represent nonimpairing cognitive fluctuations, a comorbid disorder, or the cognitive effects of substance use. False positive late-onset ADHD cases are common without careful assessment. Clinicians should carefully assess impairment, psychiatric history, and substance use before treating potential late-onset cases.
To estimate long-term stimulant treatment associations on standardized height, weight, and body mass index trajectories from childhood to adulthood in the Multimodal Treatment Study of ...Attention-Deficit/Hyperactivity Disorder (MTA).
Of 579 children with DSM-IV ADHD-combined type at baseline (aged 7.0-9.9 years) and 289 classmates (local normative comparison group LNCG), 568 and 258 respectively, were assessed 8 times over 16 years (final mean age = 24.7). Parent interview data established subgroups with self-selected Consistent (n = 53, 9%), Inconsistent (n = 374, 66%), and Negligible (n = 141, 25%) stimulant medication use, as well as patients starting stimulants prior to MTA entry (n = 211, 39%). Height and weight growth trajectories were calculated for each subgroup.
Height z scores trajectories differed among subgroups (F = 2.22, p < .0001) and by stimulant use prior to study entry (F = 2.22, p < .001). The subgroup-by-assessment interaction was significant (F = 2.81, p < .0001). Paired comparisons revealed significant subgroup differences at endpoint: Consistent was shorter than Negligible (-0.66 z units /-4.06 cm /1.6 inches, t = -3.17, p < 0.0016), Consistent shorter than Inconsistent (-0.45 z units /-2.74 cm /-1.08 inches, t = -2.39, p < .0172), and the Consistent shorter than LNCG (-0.54 z units/+3.34 cm/ 1.31 inches, t = -3.30, p < 0.001). Weight z scores initially diverged among subgroups, converged in adolescence, and then diverged again in adulthood when the Consistent outweighed the LNCG (+ 3.561 z units /+7.47 kg /+16.46 lb, p < .0001).
Compared with those negligibly medicated and the LNCG, 16 years of consistent stimulant treatment of children with ADHD in the MTA was associated with changes in height trajectory, a reduction in adult height, and an increase in weight and body mass index.
Multimodal Treatment Study of Children With Attention Deficit and Hyperactivity Disorder (MTA); https://clinicaltrials.gov/; NCT00000388.
Twelve patients with Alzheimer’s disease (AD) and 15 healthy elderly control subjects were shown sets of luminance-defined letters, texture-defined letters, luminance-defined squares, and ...texture-defined squares. They were asked to name the letters or point to the target square on each page. The stimuli were graded into four levels of difficulty based on the amount of contrast between the figure and the background. Performance was measured in terms of the maximum level of difficulty at which the participant correctly identified or located the three figures. Contrary to expectations, no significant difference was found between the performance of AD patients and control subjects on texture discrimination tasks vs. luminance discrimination tasks. However, results indicate that AD patients are impaired in performing a task requiring them to locate a texture-defined target of known shape in a noisy background field. By contrast, AD patients show no significant deficit in a task requiring them to locate a texture-defined shape in a known location. This argues that the observed deficit in the location task is not due to a failure in the system that discriminates target texture from background texture (since both location and identification tasks require the same textural discriminations), but rather to an impairment of the system responsible for “finding things” (i.e., locating known targets at unknown locations). This observation suggests that AD patients may suffer selective damage to the dorsal “Where” pathway, which is responsible for localizing objects in space.
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