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Biomedical subjects

Ronald G Barr

Publications and source records attributed to Ronald G Barr.

16 recordsLinked to original sources
PubMed2006

Age-related incidence curve of hospitalized Shaken Baby Syndrome cases: convergent evidence for crying as a trigger to shaking.

OBJECTIVE: To determine whether there is an age-specific incidence of hospitalized cases of Shaken Baby Syndrome (SBS) that has similar properties to the previously reported "normal crying curve," as a form of indirect evidence that crying is an important stimulus for SBS. DESIGN AND SETTING: The study analyzed cases of Shaken Baby Syndrome by age at hospitalization from hospital discharge data for California hospitals from October 1996 through December 2000. PATIENTS: All cases of children less than 18 months (78 weeks) of age for whom the diagnostic code for Shaken Baby Syndrome (995.55) in the International Classification of Disease, Ninth Edition, Clinical Modification was assigned. RESULTS: There were 273 hospitalizations for SBS. Like the "normal crying curve," the curve of age-specific incidence starts at 2-3 weeks, has a clear peak, and declines to baseline by about 36 weeks of age. In contrast to the normal crying curve that peaks at 5-6 weeks, the peak of SBS hospitalizations occurs at 10-13 weeks. CONCLUSIONS: The age-specific incidence curve of hospitalized SBS cases has a similar starting point and shape to the previously reported normal crying curve but the peak occurs about 4-6 weeks later. Of the likely predisposing causes, this pattern is only consistent with the properties of early crying. There are numerous explanations for the lag in the peaks between crying and SBS hospitalizations, including the possibility of repeat shakings prior to hospitalization. The importance of crying as a stimulus to SBS may provide an opportunity for preventive intervention.

Age Factors↗
PubMed2006

Glucose enhances newborn memory for spoken words.

The effect of a 2 g/kg glucose feed was compared with a water feed on retention of a spoken word in 2-4 days old infants in a between group randomized trial. Infants heard a word in 30-s trials until they demonstrated orientation (head turns towards the sound) and habituation. After a 100 s delay, infants who received glucose turned toward the word less often than infants receiving water (means 31.8 vs. 57.7%, t = 2.8, p < 0.01) implying that they remembered the word better. There were no differences between groups in measures of attention to or rate of learning of the word. Only infants who subsequently oriented towards a different word, indicating that they remained alert, were used in the data analysis. The results suggest that glucose enhanced memory for a spoken word in neonates.

Acoustic Stimulation↗
PubMed2006

Association between sleep position and early motor development.

OBJECTIVE: To compare motor performance in infants sleeping in prone versus supine positions. STUDY DESIGN: Healthy 4-month-olds (supine: n = 71, prone: n = 12) and 6-month olds (supine: n = 50, prone: n = 22) were evaluated with the Alberta Infant Motor Scale (AIMS) and Peabody Developmental Motor Scale (PDMS), and parents completed a positioning diary. Infants were reassessed at 15 months. RESULTS: At 4 months, motor scores were lower in the supine group and were less likely to achieve prone extension (P < .05). At 6 months, there were wide discrepancies on the AIMS (supine: 44.5 +/- 21.6, prone: 60.0 +/- 18.8, P = .005) and the gross motor PDMS (supine: 85.7 +/- 7.6, prone: 90.2 +/- 9.5, P = .03). Motor delays were documented in 22% of babies sleeping supine. Prone sleep-positioned infants were more likely to sit and roll. Daily exposure to awake prone positioning was predictive of motor performance in infants sleeping supine. At 15 months, sleep position continued to predict motor performance. CONCLUSIONS: Infants sleeping supine may exhibit early motor lags, associated with less time in prone while awake. This has implications for accurate interpretation of assessment of infants at risk and prevention of inappropriate referrals. Rate of infant motor development appears influenced by extrinsic factors such as positioning practices.

Age Factors↗
PubMed2006

A typical feeding enhances memory for spoken words in healthy 2- to 3-day-old newborns.

OBJECTIVE: The objective of this study was to determine whether healthy 2- to 3-day-old newborns have better memory of a spoken word after a typical feeding (breast milk or formula) than before a feeding and, if so, whether memory is related to blood glucose. METHODS: A naturalistic study was conducted in which delayed recognition memory of a spoken word was examined in 60 healthy 2- to 3-day-old newborns either 120 minutes after their previous feeding (preprandial) or 30 minutes after their last feeding (postprandial). In this procedure, infants initially turn their head toward a novel word (orientation) and with repeated presentations cease turning toward it (habituation). Mean number of trials to reach orientation and habituation criteria provides measures of attention and rate of learning, respectively. After a 100-second delay, the word is presented again. Infants either turn toward it, indicating that they have forgotten it, or remain habituated, indicating that they remembered the word. Percentage of trials with head turns toward the word after the delay is the principal dependent measure. RESULTS: The postprandial group was split at the median for blood glucose to define high- and low-glucose groups. All 3 groups showed similar rates of orientation and habituation. On reexposure to the word during postdelay trials, the preprandial group displayed less retention than the postprandial high and low groups. No correlation was found between memory and blood glucose levels. The postprandial high blood glucose level differed statistically from the preprandial level, whereas the postprandial low level did not. CONCLUSIONS: Memory for spoken words in newborns is better after a typical milk feeding than before a feeding. This feeding effect is specific to memory and does not include attention or rate of learning. Also, it is not necessarily associated with increased blood glucose. It remains to be seen whether feeding enhances memory for other types of stimuli and what implications this may have for development.

Attention↗
PubMed2005

Executive functions and methylphenidate response in subtypes of attention-deficit/hyperactivity disorder.

BACKGROUND: Oculomotor tasks are a well-established means of studying executive functions and frontal-striatal functioning in both nonhuman primates and humans. Attention-deficit/hyperactivity disorder (ADHD) is thought to implicate frontal-striatal circuitry. We used oculomotor tests to investigate executive functions and methylphenidate response in two subtypes of ADHD. METHODS: Subjects were boys, aged 11.5-14 years, with ADHD-combined (n = 10), ADHD-inattentive (n = 12), and control subjects (n = 10). Executive functions assessed were motor planning (tapped with predictive saccades), response inhibition (antisaccades), and task switching (saccades-antisaccades mixed). RESULTS: The ADHD-combined boys were impaired relative to control subjects in motor planning (p < .003) and response inhibition (p < .007) but not in task switching (p > .92). They were also significantly impaired relative to ADHD-inattentive boys, making fewer predictive saccades (p < .03) and having more subjects with antisaccade performance in the impaired range (p < .04). Methylphenidate significantly improved motor planning and response inhibition in both subtypes. CONCLUSIONS: ADHD-combined but not ADHD-inattentive boys showed impairments on motor planning and response inhibition. These deficits might be mediated by brain structures implicated specifically in the hyperactive/impulsive symptoms. Methylphenidate improved oculomotor performance in both subtypes; thus, it was effective even when initial performance was not impaired.

Adolescent↗
PubMed2005

Influence of supine sleep positioning on early motor milestone acquisition.

This study aimed to determine whether supine sleep-positioned infants have delayed motor skills at age 4 and 6 months, and if delays are associated with decreased exposure to prone position. One 4 and one 6-month-old sample of healthy infants born at term were recruited. Motor assessments included the Peabody Developmental Motor Scale (PDMS) and Alberta Infant Motor Scale (AIMS). Parents completed an infant behavior diary for 3 consecutive days. Seventy-one 4-month-old infants were assessed (38 males; mean age 4.4 mo, standard deviation [SD] 0.2). Mean motor scores were close to normative standards (AIMS 47.7, SD 19.6; PDMS gross motor quotient [GMQ] 96.3, SD 6.5; PDMS fine motor quotient [FMQ] 99.2, SD 4.8). No infant scored below cut-off values used to identify motor delay. Milestones less likely to be achieved included extended arm support in prone, hands to feet in supine, and sitting with arm support. Exposure to 'tummy time' while awake was correlated with AIMS scores (r = 0.38, p < 0.01). F i fty 6-month-old infants were assessed (21 males; mean age 6.4 mo, SD 0.4). Mean scores were shifted down for all scales, and as much as 1 SD for PDMS (AIMS 44.5, SD 21.6; PDMS GMQ 85.7, SD 7.6; PDMS FMQ 88.9, SD 9.0). Only 22% of 6-month-olds could sit without arm support versus 50% expected in a normative sample. Remarkably, 22% of our sample exhibited gross motor delays (quotient <78). Tummy time (awake) was significantly associated with the AIMS (r = 0.64) and PDMS GMQ (r = 0.55) and FMQ (r = 0.33) quotients, even after adjusting for confounders. Typically developing infants who were sleep-positioned in supine had delayed motor development by age 6 months, and this was significantly associated with limited exposure to awake prone positioning. This has important implications for interpreting motor assessments of infants at risk and for preventing inappropriate referrals.

Age Factors↗
PubMed2005

Prolonged and unsoothable crying bouts in infants with and without colic.

ABSTRACT.: The authors sought to determine which features of early distress were "excessive" and specific to the first months of life as described by diary recordings. In a short-term, longitudinal, controlled study, total daily amount, frequency, and bout duration of fussing, crying, and unsoothable crying were derived from validated diaries kept by parents of infants with and without diary-defined colic at 6 weeks and 5 months recruited from primary pediatrics practices. By definition, infants with colic demonstrated more distress at 6 weeks, but they also had a much greater reduction in distress by 5 months and more distress during the fifth month. However, bout frequencies and bout durations showed different patterns. Bout duration was longer for the colic group only at 6 weeks; the difference completely disappeared by 5 months. Bout frequency was higher for the colic group at 6 weeks and 5 months, but the reduction across ages was similar in infants with and without colic. These patterns were true for all distress modalities (fussing, crying, and unsoothable crying). Unsoothable crying was present in significant amounts only at 6 weeks but virtually disappeared by 5 months. The authors conclude that prolonged distress bouts and unsoothable crying are specific to the first few months and more common, though not unique, in infants with colic. This implies that our understanding of colic may depend more on why these infants cry longer once started than what makes infants cry. These features of parental experience may be important in preventive efforts to reduce negative impacts of early increased crying such as shaken baby syndrome.

Adult↗
PubMed2004

Stress during pregnancy affects general intellectual and language functioning in human toddlers.

Prenatal maternal stress has been shown to impair functioning in nonhuman primate offspring. Little is known about the effects of prenatal stress on intellectual and language development in humans because it is difficult to identify sufficiently large samples of pregnant women who have been exposed to an independent stressor. We took advantage of a natural disaster (January 1998 ice storm in Québec, Canada) to determine the effect of the objective severity of pregnant women's stress exposure on general intellectual and language development of their children. Bayley Mental Development Index (MDI) scores and parent-reported language abilities of 58 toddlers of mothers who were exposed to varying levels of prenatal stress were obtained at 2 y of age. The hierarchical multiple regression analyses indicated that the toddlers' birth weight and age at testing accounted for 12.0% and 14.8% of the variance in the Bayley MDI scores and in productive language abilities, respectively. More importantly, the level of prenatal stress exposure accounted for an additional 11.4% and 12.1% of the variance in the toddlers' Bayley MDI and productive language abilities and uniquely accounted for 17.3% of the variance of their receptive language abilities. The more severe the level of prenatal stress exposure, the poorer the toddlers' abilities. The level of prenatal stress exposure accounted for a significant proportion of the variance in the three dependent variables above and beyond that already accounted for by non-ice storm-related factors. We suspect that high levels of prenatal stress exposure, particularly early in the pregnancy, may negatively affect the brain development of the fetus, reflected in the lower general intellectual and language abilities in the toddlers.

Birth Weight↗
PubMed1999

Effects of methylphenidate on complex cognitive processing in attention-deficit hyperactivity disorder.

Three experiments were conducted to explore the effects of methylphenidate (MPH), attention-deficit hyperactivity disorder (ADHD) diagnosis, and age on performance on a complex visual-memory search task. Results showed that the effects of MPH varied with information load. On low-processing loads, all doses of MPH helped children with ADHD to improve accuracy with no cost to reaction time (RT), whereas on high loads, higher MPH doses improved error rates while slowing RT. Without medication, children with ADHD showed high error rates and slow RTs across both low and high loads, as did younger, normal control children. Because MPH slowed performance on only the most difficult, high-load conditions, it is argued that the drug improves self-regulatory ability, enabling children with ADHD to adapt differentially to high and low loads.

Adolescent↗
PubMed1994

The cold pressor test in children: methodological aspects and the analgesic effect of intraoral sucrose.

To determine whether intraoral sucrose has analgesic-like effects in pre-pubertal children and to explore the utility of an ethical and viable laboratory test of nociceptive stimulation in this age group, 8-11-year-olds (n = 42) underwent the cold pressor test (CPT) at 10 degrees C on each of 2 successive days, while holding either 24% sucrose or water in their months. Outcome measures used were threshold (time at which the arm first started to hurt), tolerance (when children removed their arms because they could not stand it any more) and visual analogue scale (VAS) ratings of the intensity of sensation. To ensure validity of the data obtained in this age group, some responses were rejected according to established decision rules and blind to group assignment. Each measure produced interesting data but also had limitations. Threshold data that did not meet validity criteria occurred more frequently with younger children. Tolerance data was not available for a significant proportion (57%) of children, since they left their arms in the water for the maximum time allowed (4 min). This occurred more frequently on the second day of testing and with younger children. Inability to perform adequately on the VAS also occurred, but was not related to age. Holding sucrose in the mouth was associated with a significant 35% prolongation of the children's threshold times relative to water, but there was no detectable effect on tolerance and intensity ratings. It is concluded that the analgesic properties of intraoral sucrose, seen previously in human newborns and rat pups, may also be present in pre-pubertal children.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1989

Psychophysiologic responses to a realistic laboratory abdominal pain stimulus.

Small doses of the carbohydrate lactulose are widely used in the clinical setting to assess small bowel transit time because lactulose is not absorbed by the small intestine and its arrival in the intestine can be detected non-invasively by breath hydrogen testing. In this study, doses of this safe, widely used substance higher than those typically administered for transit tests were given to 12 healthy young adult men to produce symptoms of gas and intestinal distention similar to those commonly experienced by patients with irritable bowel syndrome and recurrent abdominal pain. Comparison of subjective and physiological responses to the administration of 0 and 30 g of lactulose in a double-blind placebo-controlled trial demonstrated that the 30 g lactulose dose produced significant increases in a number of measures reflecting the intra-intestinal pain stimulus. The results of the present study indicate that lactulose is a realistic and ethically acceptable stimulus for the production of transient mild abdominal pain in the laboratory.

Abdomen↗
PubMed1982

Potential biobehavioral mechanisms of recurrent abdominal pain in children.

To explain why otherwise healthy children experience recurrent episodes of abdominal pain (the recurrent abdominal pain syndrome, or RAP), it has been hypothesized that the child with RAP demonstrates: (1) a deficit in autonomic nervous system recovery to stress, and/or (2) an enhanced behavioral and subjective response to pain. To evaluate the validity of these assumptions, children with RAP (9-14 years) and hospital and healthy controls matched for age, sex, ethnicity and SES were exposed to a cold pressor stimulus (0 +/- 1 degree C). Autonomic (peripheral vasomotor and heart rate), somatic (forearm EMG), subjective (pain intensity and distress), and behavioral (facial expression) responses were recorded during baseline, stressor and recovery periods. At all 4 levels of observation, the cold pressor stimulus resulted in significant autonomic, somatic, subjective and behavioral arousal. However, no significant differential response across the 3 groups was noted for any measure and, in particular, no recovery deficit in autonomic arousal was demonstrated. These findings do not support the assumption of a differential response to an acute laboratory induced stress in children with RAP compared to control children.

Abdomen↗