Longitudinal caregiver-reported motor development in infants born at term and preterm

AIM

To examine the extent to which estimates of a latent trait or underlying construct of motor ability differ in infants born at term and preterm, based on caregiver ratings of the motor domain of PediaTrac v3.0.

METHOD

The sample consisted of 571 caregiver-infant dyads (331 born at term, 240 born preterm), 48% female, with 51.7% of caregivers identifying as an ethnic minority. Latent trait of motor ability was estimated based on item response theory modeling. Gestational group differences (term and preterm birth) were examined at the newborn/term-equivalent, 2-, 4-, 6-, 9-, and 12-month time points.

RESULTS

Caregiver ratings of latent trait of motor ability were reliably modeled across the range of abilities at each time point. While the group born preterm exhibited significantly more advanced motor abilities at the term-equivalent time point, by 6 months the group born at term was more advanced. Biological sex difference main and interaction effects were not significant.

INTERPRETATION

Caregivers provided reliable, longitudinal estimates of motor ability in infancy, reflecting important differences in the motor development of infants born at term and preterm. The findings suggest that significant motor development occurs in infants born preterm from birth to the term-equivalent time point and provide a foundation to examine motor growth trajectories as potential predictors in the early identification of neurodevelopmental conditions and needs.

WHAT THIS PAPER ADDS

Longitudinal caregiver ratings of motor function in early infancy yielded reliable estimates of the latent trait of motor ability. Motor ability at the term-equivalent time point was higher in infants born preterm than infants born at term.

Measuring Early Relational Health Using PediaTrac TM in a Diverse Sample of Infant-Caregiver Dyads

OBJECTIVE

Early relational health (ERH) is a key developmental predictor and outcome in infancy and early childhood that reflects social-emotional well-being and promotes resilience throughout childhood. Currently, there is no gold-standard developmental screening tool for ERH in pediatric care settings. This study examined the psychometric properties of items assessing ERH that are part of a web-based, caregiver-report screening tool called PediaTrac TM . It was hypothesized that ERH could be reliably estimated and that second-order factors would be revealed within the latent construct ERH.

METHOD

Participants included 571 caregivers of term (n = 331; ≥37 weeks) and preterm (n = 240; <37 weeks) infants recruited shortly after birth from several academic medical centers and a community health clinic. Caregivers completed PediaTrac modules at birth and 2, 4, 6, 9, 12, 15, and 18 months; data for this study are from the newborn through 12-month periods.

RESULTS

Results from Item Response Theory Graded Response Modeling revealed excellent reliability for the PediaTrac ERH domain at all time points, ranging from 0.96 to 0.98. Exploratory factor analyses revealed 4 to 5 second-order factors, representing Parent-Child Relationship, Parent Distress, Parenting Stress, Parenting Efficacy, Sensitivity, and Perceptions of Child, depending on period.

CONCLUSION

The caregiver-report developmental screening tool, PediaTrac, reliably measures ERH during the first year of life. The measure has promising clinical utility in pediatric clinic settings for tracking ERH over time to ensure early social-emotional well-being and to identify concerns as early as possible.

Motor networks in children with autism spectrum disorder: a systematic review on EEG studies

Motor disturbance and altered motor networks are commonly reported in individuals with autism spectrum disorder (ASD). It has been suggested that electroencephalogram (EEG) can be used to provide exquisite temporal resolution for understanding motor control processes in ASD. However, the variability of study design and EEG approaches can impact our interpretation. Here, we conducted a systematic review on recent 11 EEG studies that involve motor observation and/or execution tasks and evaluated how these findings help us understand motor difficulties in ASD. Three behavior paradigms with different EEG analytic methods were demonstrated. The main findings were quite mixed: children with ASD did not always show disrupted neuronal activity during motor observation. Additionally, they might have intact ability for movement execution but have more difficulties in neuronal modulation during movement preparation. We would like to promote discussions on how methodological selections of behavioral tasks and data analytic approaches impact our interpretation of motor deficits in ASD. Future EEG research addressing the inconsistency across methodological approaches is necessary to help us understand neurophysiological mechanism of motor abnormalities in ASD.

Caregiver-reported newborn term and preterm motor abilities: psychometrics of the PediaTracTM Motor domain

BACKGROUND

Approximately 5-10% of children exhibit developmental deviations in motor skills or other domains; however, physicians detect less than one-third of these abnormalities. Systematic tracking and early identification of motor deviations are fundamental for timely intervention.

METHODS

Term and preterm neonates were prospectively assessed at the newborn (NB) period in a study of the psychometric properties of the Motor (MOT) domain of PediaTrac^TM v3.0, a novel caregiver-based development tracking instrument. Item response theory graded response modeling was used to model item parameters and estimate theta, an index of the latent trait, motor ability. Exploratory factor analysis (EFA) was conducted to examine the dimensionality and factor structure.

RESULTS

In a cohort of 571 caregiver/infant dyads (331 term, 240 preterm), NB MOT domain reliability was high (rho = 0.94). Item discrimination and item difficulty of each of the 15 items could be reliably modeled across the range of motor ability. EFA confirmed that the items constituted a single dimension with second-order factors, accounting for 43.20% of variance.

CONCLUSIONS

The latent trait, motor ability, could be reliably estimated at the NB period.

IMPACT

The caregiver-reported Motor domain of PediaTrac provides a reliable estimate of the latent trait of motor ability during the newborn period. This is the first known caregiver-reported instrument that can assess motor ability in the newborn period with high reliability in term and preterm infants. Item response theory methods were employed that will allow for future characterization of developmental subgroups and motor trajectories. The PediaTrac Motor domain can support early identification of at-risk infants. Including caregivers in digital reporting and child-centered monitoring of motor functioning may improve access to care.

A-142 The Impact of Temperament on Sleep in Term and Preterm Infants

Objective: Research has examined temperament’s effect on infant sleep. Poorer sleep has been associated with higher negative affectivity, lower surgency, and lower regulation. Limited research has examined gestational age in this association, despite findings that gestational age is individually related to temperament and infant sleep. Due to the increased risk associated with prematurity, we hypothesized that the aforementioned associations between temperament and poorer sleep would be stronger for children with lower gestational age.

Methods: Socioeconomically diverse term and preterm caregiver/infant dyads (N=571) were recruited in a longitudinal, multisite study. Temperament was measured at 9 months using the Infant Behavior Questionnaire. Infant sleep (IS) and parent perception of sleep (PP) were measured at 15 months using the Brief Infant Sleep Questionnaire. Correlational analyses examined associations between temperament and sleep, while regression analyses explored gestational age as a moderator in this association.

Results: Higher negative affectivity was associated with poorer IS and PP (r=-.18, r=-.20, respectively, p&lt;.01). Higher surgency was only associated with poorer IS (r=-.16, p&lt;.01), while higher regulation/orienting was only associated with better PP (r=.16, p&lt;.01). Gestational age was not a significant moderator.

Conclusion: Lack of moderation suggests gestational age does not differentially affect the association between temperament and sleep. Higher negative affectivity and higher surgency were associated with poorer IS, suggesting a target group for intervention. Children with higher negative affectivity may be more likely to receive intervention than those with higher surgency, as parents view their sleep as problematic. Children with higher surgency may require increased monitoring to receive intervention when warranted.

The influence of sociodemographic factors and response style on caregiver report of infant developmental status

Caregiver report is the most feasible way to assess early childhood development but is susceptible to the influences of response style and sociodemographic factors. In a sample of 571 caregiver-infant dyads (47.8% female; 48% White), we compared caregiver reports on the Ages and Stages Questionnaire-Third Edition (ASQ-3) with reports on a novel, web-based assessment, PediaTrac™. Ratings on PediaTrac correlated with ratings on the ASQ-3 at all time points (2, 4, 6, and 9 months). Caregiver age, response style, and sociodemographic factors accounted for significant variance on both measures. Developmental reporting of early childhood skills is influenced by caregiver response style and sociodemographic factors. These influences must be considered in order to ensure the accurate identification of infant developmental status.

PediaTrac V.3.0 protocol: a prospective, longitudinal study of the development and validation of a web-based tool to measure and track infant and toddler development from birth through 18 months

INTRODUCTION

The need for an efficient, low-cost, comprehensive measure to track infant/toddler development and treatment outcomes is critical, given the importance of early detection and monitoring. This manuscript describes the protocol for the development and testing of a novel measure, PediaTrac, that collects longitudinal, prospective, multidomain data from parents/caregivers to characterise infant/toddler developmental trajectories in term and preterm infants. PediaTrac, a web-based measure, has the potential to become the standard method for monitoring development and detecting risk in infancy and toddlerhood.

METHODS AND ANALYSES

Using a multisite, prospective design, primarcaregivers will complete PediaTrac V.3.0, a survey tool that queries core domains of early development, including feeding/eating/elimination, sleep, sensorimotor, social/sensory information processing, social/communication/cognition and early relational health. Information also will be obtained about demographic, medical and environmental factors and embedded response bias indices are being developed as part of the measure. Using an approach that systematically measures infant/toddler developmental domains during a schedule that corresponds to well-child visits (newborn, 2, 4, 6, 9, 12, 15, 18 months), we will assess 360 caregiver/term infant dyads and 240 caregiver/preterm infant dyads (gestational age <37 weeks). Parameter estimates of our items and latent traits (eg, sensorimotor) will be estimated by theta using item response theory-graded response modelling. Participants also will complete legacy (ie, established) measures of development and caregiver health and functioning, used to provide evidence for construct (discriminant) validity. Predictive validity will be evaluated by examining relationships between the PediaTrac domains and the legacy measures in the total sample and in a subsample of 100 participants who will undergo a neurodevelopmental assessment at 24 months of age.

ETHICS AND DISSEMINATION

This investigation has single Institutional Review Board (IRB) multisite approval from the University of Michigan (IRB HUM00151584). The results will be presented at prominent conferences and published in peer-reviewed scientific journals.

Differences in Sensorimotor Development Among U.S. Infants Receiving Breastmilk and/or Formula in the First 6-Months From the PediaTrac™ Project

Objectives

Achieving sensorimotor (SEM) milestones is one measure of early infant brain development promoted through higher docosahexaenoic acid (DHA) levels. Both breastmilk and formula contain DHA, with a global level of 0.32% in breastmilk and many formula brands. However, a 2017 study of Midwestern U.S. mothers found significantly lower breastmilk DHA levels. It was thus hypothesized that infants fed formula would have higher SEM scores. The objective of this study was to measure differences in SEM development between infants fed breastmilk, formula, or a combination in participants of the PediaTrac™ Project. PediaTrac is a web-based measure providing longitudinal, real time, multidomain data on infant and toddler growth and development at time periods corresponding to well child visits.

Methods

Using PediaTrac, data were collected from 548 caregiver-infant dyads across multiple Midwestern sites. Caregivers reported the primary nutrition source as breastfeeding, formula or combination. Their responses to gross and fine motor function questions were used to create a SEM composite, Percent of Maximum Possible (POMP) score at newborn (NB), 2-, 4- and 6-months. Data were analyzed via ANOVA and Tukey test using SPSS.

Results

Infants fed formula had statistically higher mean SEM scores at NB (M = 0.618Formula, M = 0.590Breast, p = 0.017), 2- (M = 0.706Formula, M = 0.680Breast, p = 0.006) and 6-months (M = 0.727Formula, M = 0.696Breast, p = 0.014) compared to breastfed infants. Mean SEM scores of combination fed infants were higher than breastfed infants at 2- (M = 0.701Combination, M = 0.680Breast, p = 0.184), 4- (M = 0.684Combination, M = 0.673Breast, p = 0.573) and 6-months (M = 0.704Combination, M = 0.696Breast, p = 0.895), despite no significant differences between scores.

Conclusions

Formula fed infants showed consistently higher SEM scores than breastfed infants in the first 6-months. These findings contradict previous research, indicating a need for further investigation into variables contributing to these discrepancies such as maternal breastmilk DHA concentrations, socioeconomic factors, site specific confounds, accuracy of parent reports of motor development, etc.

Funding Sources

Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health. EMU College of Health & Human Services Research Support Award.

Growth Changes in Pre-Term and Full-Term Infants over the First 6-months of Life from the PediaTrac™ Project

Objectives

Changes in body weight, length and head circumference have long been indicators of infant growth and development. PediaTrac™ is a web-based measure designed to engage caregivers in the gathering of longitudinal, real-time, multi-domain data on infant/toddler growth and development at time periods corresponding to well-child visits. The purpose of this study was to assess the changes in growth (weight, length, head circumference) between the newborn and 6 m time periods for both term and pre-term (&lt;37 weeks gestational age) infants as influenced by type of feeding (breast milk versus formula).

Methods

PediaTrac™ was used to gather data from caregivers and their infants across multiple sites (Michigan and Ohio).To date, 370 caregivers of both pre-term and term infants have completed PediaTrac™ regarding their infants’ growth and development. They reported their infant's body weight, length and head circumference, as well as the type of liquid nutrition their infants received at birth and 6 m. Caregiver responses were managed using REDCap, a secure platform for building and managing online databases and surveys. Data were analyzed using both R and SPSS.

Results

PediaTrac™ was used to gather data from caregivers and their infants across multiple sites (Michigan and Ohio). To date, 370 caregivers of both pre-term and term infants have completed PediaTrac™ regarding their infants’ growth and development. They reported their infant's body weight, length and head circumference, as well as the type of liquid nutrition their infants received at birth and 6 m. Caregiver responses were managed using REDCap, a secure platform for building and managing online databases and surveys. Data were analyzed using both R and SPSS.

Conclusions

By 6 m of age, fewer caregivers were feeding their infants breast milk. However, there were no significant differences in weight between infants fed breast milk and those fed formula.

Funding Sources

Eunice Kennedy Shriver National Institute of Child Health & Human Development of the National Institutes of Health. Eastern Michigan University College of Health and Human Services Research Support Award.

C-48 Attachment and SES at Newborn, Two, and Four Months Related to Communication Development at Nine and Twelve Months

Objective

Previous literature linked secure infant attachment to subsequent communication competency (Murray & Yingling, 2000). Less is known about that relationship in families of varying SES. This study explores how attachment and income at newborn, two, and four months correspond with communication development at nine and twelve months.

Methods

Longitudinal (n = 30) and cross-sectional (n = 102) reports from PediaTrac□, a parent-report web-based survey to track development (Lajiness-O’Neill, et al., 2018), were collected at newborn (NB; n = 41), two (2m; n = 38), four (4m; n = 37), nine (9m; n = 38), and twelve months (12m; n = 36). The cross-sectional sample had higher income (p = .01). Attachment was measured using PediaTrac□ and the Postpartum Bonding Questionnaire (PBQ; Brockington, Fraser & Wilson, 2006). Communication was measured using PediaTrac□.

Results

A linear regression model predicted communication development at 9m and 12m from attachment and income at NB, 2m, and 4m. PBQ attachment at 2m significantly predicted communication at 9m (b = 0.12, t = 2.28, p = .049). However, income was not significant, and neither attachment nor income at NB, 2m, or 4m predicted communication at 12m.

Conclusions

More secure attachment at two months was related to better communication outcomes at nine months regardless of SES. This finding highlights the importance of parent-infant relationships at two months of age on development, indicating further research on methods to promote secure attachment and positive parent-infant interaction in families of varying SES.

Potential Role of Cortisol in Social and Memory Impairments in Individuals with 22q11.2 Deletion Syndrome

22q11.2 Deletion syndrome is a genetic disorder characterized by physiological and psychological symptoms. This study investigated the role of cortisol on the social and cognitive impairments in children with 22q11.2. A total of 11 children with 22q11.2 were assessed for baseline cortisol levels and received broad neuropsychological testing. Results were compared with 11 controls. Children with 22q11.2 had significantly higher cortisol levels. A significant negative correlation was observed between the general memory and attention/concentration indices of the Wide Range Assessment of Memory and Learning, 2nd edition and cortisol concentrations in the control population. These data provide evidence of a possible causal mechanism that underlies social impairments in stress disorders.

Alterations in Memory and Impact on Academic Outcomes in Children Following Allogeneic Hematopoietic Cell Transplantation

The prevalence of late effects following allogeneic hematopoietic cell transplantation (HCT), a curative treatment for pediatric leukemia, is high: 79% of HCT recipients experience chronic medical conditions. The few extant studies of cognitive late effects have focused on intelligence and are equivocal about HCT neurotoxicity. In an archival study of 30 children (mean transplant age = 6 years), we characterize neuropsychological predictors of academic outcomes. Mean intellectual and academic abilities were average, but evidenced extreme variability, particularly on measures of attention and memory: ∼25% of the sample exhibited borderline performance or lower. Medical predictors of outcome revealed paradoxically better memory associated with more severe acute graft-versus-host disease (GVHD) and associated with steroid treatment. Processing speed and memory accounted for 69% and 61% of variance in mathematics and reading outcomes, respectively. Thus, our findings revealed neurocognitive areas of vulnerability in processing speed and memory following HCT that contribute to subsequent academic difficulties.

Visual attention shifting in autism spectrum disorders

INTRODUCTION

Abnormal visual attention has been frequently observed in autism spectrum disorders (ASD). Abnormal shifting of visual attention is related to abnormal development of social cognition and has been identified as a key neuropsychological finding in ASD. Better characterizing attention shifting in ASD and its relationship with social functioning may help to identify new targets for intervention and improving social communication in these disorders. Thus, the current study investigated deficits in attention shifting in ASD as well as relationships between attention shifting and social communication in ASD and neurotypicals (NT).

METHOD

To investigate deficits in visual attention shifting in ASD, 20 ASD and 20 age- and gender-matched NT completed visual search (VS) and Navon tasks with attention-shifting demands as well as a set-shifting task. VS was a feature search task with targets defined in one of two dimensions; Navon required identification of a target letter presented at the global or local level. Psychomotor and processing speed were entered as covariates. Relationships between visual attention shifting, set shifting, and social functioning were also examined.

RESULTS

ASD and NT showed comparable costs of shifting attention. However, psychomotor and processing speed were slower in ASD than in NT, and psychomotor and processing speed were positively correlated with attention-shifting costs on Navon and VS, respectively, for both groups. Attention shifting on VS and Navon were correlated among NT, while attention shifting on Navon was correlated with set shifting among ASD. Attention-shifting costs on Navon were positively correlated with restricted and repetitive behaviors among ASD.

CONCLUSIONS

Relationships between attention shifting and psychomotor and processing speed, as well as relationships between measures of different aspects of visual attention shifting, suggest inefficient top-down influences over preattentive visual processing in ASD. Inefficient attention shifting may be related to restricted and repetitive behaviors in these disorders.

Multimodal imaging of temporal processing in typical and atypical language development

New approaches to understanding language and reading acquisition propose that the human brain's ability to synchronize its neural firing rate to syllable-length linguistic units may be important to children's ability to acquire human language. Yet, little evidence from brain imaging studies has been available to support this proposal. Here, we summarize three recent brain imaging (functional near-infrared spectroscopy (fNIRS), functional magnetic resonance imaging (fMRI), and magnetoencephalography (MEG)) studies from our laboratories with young English-speaking children (aged 6-12 years). In the first study (fNIRS), we used an auditory beat perception task to show that, in children, the left superior temporal gyrus (STG) responds preferentially to rhythmic beats at 1.5 Hz. In the second study (fMRI), we found correlations between children's amplitude rise-time sensitivity, phonological awareness, and brain activation in the left STG. In the third study (MEG), typically developing children outperformed children with autism spectrum disorder in extracting words from rhythmically rich foreign speech and displayed different brain activation during the learning phase. The overall findings suggest that the efficiency with which left temporal regions process slow temporal (rhythmic) information may be important for gains in language and reading proficiency. These findings carry implications for better understanding of the brain's mechanisms that support language and reading acquisition during both typical and atypical development.

Memory and learning in pediatric traumatic brain injury: a review and examination of moderators of outcome

This article reviews empirically supported assessment methods to examine impairments in memory and learning following pediatric traumatic brain injury (TBI). Critical factors affecting outcome are explored with an emphasis on an examination of age at injury. The article closes with discussion of current evidence-based interventions for deficits in memory and learning following pediatric TBI.

Order of Conners' CPT-II administration within a cognitive test battery influences ADHD indices

OBJECTIVE

To study the effect of administration sequence on Conner's continuous performance test (CPT-II) scores in clients requesting psychological assessment. It was hypothesized that when administered at the end rather than beginning of a test battery, the test scores will show higher symptom severity. If present, order effects may cause the over- or underdiagnosing of ADHD.

METHOD

Participants were recruited at a Midwestern university's training clinic (16 men, 9 women; mean age = 22.4, SD = 10.2). The CPT-II was administered twice to each client: once at the beginning of the testing session and once at the end of their appointment. The clients completed at least a full Wechsler intelligence battery in between the CPT-II administrations.

RESULTS

Clients' ADHD index score (interpreted as percent confidence in an ADHD diagnosis) is more impaired at Time 2 (M = 53.3, SD = 29.0) compared to Time 1 (M = 39.4, SD = 22.5): t (24) = 3.93, p < .05, Cohen's d = .79. The number of T-scores above 60 on the subscales also changed from Time 1 (M = 1.92, SD = 1.73) to Time 2 (M = 3.12, SD = 2.05): t(24) = 3.47, p < .01, Cohen's d = .71.

CONCLUSIONS

If the CPT-II is administered later in a sequence of tests, it is more likely to yield scores in the impaired range. Order effects are more pronounced in individuals diagnosed with ADHD. Recommendations include the adoption of a standardized administration sequence, further research to investigate the nature of order effects, and a strategic use of order effects in ADHD assessment.

Treatment effects of Fast ForWord demonstrated by magnetoencephalography (MEG) in a child with developmental dyslexia

Treatment effects of Fast ForWord, hypothesized to ameliorate temporal processing deficits, were demonstrated by magnetoencephalography in a child with dyslexia using four paradigms: Word/Non-word Reading (NW), Grapheme-to-Phoneme Matching (GP), Verbal, and Spatial Working Memory (VWM, SWM). Shifts in brain activation from right inferior frontal and temporal to left frontal, bilateral supramarginal, and transverse temporal regions occurred during GP. During NW, shifts progressed from (1) right or bilateral anterior and superior to (2) left, inferior frontal, to (3) left, superior posterior temporoparietal, to (4) left, inferior, posterior temporooccipital regions. Reading and written language improvements were noted in passage comprehension and spelling.

Long-term estrogen replacement is associated with improved nonverbal memory and attentional measures in postmenopausal women

OBJECTIVE

To determine the cognitive domains improved or preserved by long-term hormone replacement therapy (HRT).

DESIGN

A comprehensive neuropsychological test battery was administered to healthy postmenopausal women who had been treated or not treated with long-term HRT without interruption since menopause.

SETTING

Women were recruited by advertisement from a university town and surrounding areas.

PATIENT(S)

Women 60 years or older were studied who were treated (n = 16) or not treated (n = 13) with HRT.

INTERVENTION(S)

Neuropsychological testing included tests of memory, verbal fluency, executive functions, attention and concentration, and psychomotor function. Tests of intellectual function, depressive symptoms, and emotional functioning assessed general functions and comparability of the groups.

MAIN OUTCOME MEASURE(S)

Neuropsychological testing scores were compared between groups.

RESULT(S)

No statistically significant differences between the groups were found for general demographic, intellectual, and psychological measures. Scores from both the Weschler Memory Scale Visual Reproduction (delayed recall) and the Digit Vigilance Test (attention) showed statistically significant better performance and fewer errors in the group of women on HRT.

CONCLUSION(S)

Long-term postmenopausal HRT is associated with higher scores in tests of nonverbal memory and attention.

Cognitive function in euthymic bipolar I disorder

Recent reports have suggested the presence of persistent cognitive impairments in patients diagnosed with Bipolar Disorder even after prolonged euthymic phases. In this work, various domains of cognitive function were examined in asymptomatic patients diagnosed with Bipolar I Disorder (BDI) in comparison with healthy subjects. Fifteen otherwise healthy BDI patients with a prior history of psychosis during mania completed a neuropsychological testing battery after a prolonged asymptomatic remission. Their scores were compared to those of individually matched healthy subjects with unpaired two-tailed t-tests at P<0.01. Relationships between cognitive performance measures and clinical variables related to illness severity were also examined with Pearson correlations, P<0.05. We detected poorer performance on measures of verbal learning, executive functioning and motor coordination in BDI patients compared to control volunteers. Scores on tests of executive functioning were negatively correlated with the number of episodes of mania and depression. Social and occupational scores were also associated with a poorer performance on measures of verbal learning and executive function. Euthymic BDI patients, therefore, demonstrate reductions in specific cognitive domains even after prolonged asymptomatic phases. Some of these deficits appear to be associated with a more severe course of illness and poorer social and occupational functioning.

Neuropsychological function and cerebral glucose utilization in isolated memory impairment and Alzheimer's disease

We hypothesized that 20 patients with isolated memory impairment (IMI) would demonstrate [18F]-2-fluoro-2-deoxy-D-glucose utilization and a progression of neuropsychological symptoms consistent with Alzheimer's disease (AD). IMI subjects performed similarly to AD in recall and verbal fluency, but comparable to normal subjects in other areas of cognitive functioning. A positron emission tomography (PET) diagnostic index based on parietal Z-scores categorized IMI patients into normal and abnormal metabolic patterns. Ten of the original 20 IMI patients (50%) reflected PET AD abnormalities. Clinical information was available for IMI patients at three-year follow-up. Ten (50%) had converted to AD, three were found to have pseudodementia and the seven remained IMI. Of the 10 IMI patients with an originally normal PET index, three (30%) were diagnosed with AD at three years. Of the 10 with an abnormal index originally, seven (70%) converted to AD. The finding that memory deficit in IMI was as pronounced as that in AD patients is consistent with the notion that memory is an initial symptom of AD. A substantial number of the IMI patients reflected regional hypometabolism similar to AD, suggesting that IMI is likely an early stage in progressive dementia. A large percentage of IMI patients converted clinically to AD within three years of initial study, though we observed impaired memory functioning well before a clinical diagnosis of AD could be made. In addition to potential clinical utility, IMI and PET represent an opportunity to study dementia in relation to brain chemistry at a time when brain pathology is in the process of development.

Technology in the assessment of learning disability

Recent neuroradiologic and brain imaging technologies, along with methods for displaying electrophysiologic data, have promulgated active exploration in the assessment of learning disability with attempts to improve diagnostic precision and elucidate the neurobiological substrates of learning disorders. The following article reviews these techniques and explores the research that has been conducted in this area over the past two decades. Initial investigations attempted to elucidate irregularities or abnormalities of brain morphology in individuals with learning disability utilizing computerized tomography (CT). The current standard for structural imaging of the brain is magnetic resonance (MR) imaging, which has allowed for greater specificity in identifying brain abnormalities. More recently, functional magnetic resonance imaging (fMRI) has been postulated as holding some promise in distinguishing anatomic/function differences in LD. Electrophysiological (EEG) and metabolic imaging techniques offer methods by which human brain activity can be studied during cognitive processes. Computerized EEG studies including evoked potentials (EP) or event-related potentials (ERP), spectral EEG analysis, and topographic EEG brain mapping have also identified a number of brain irregularities in individuals with learning disabilities, though no consistent exemplars have emerged. Studies with positron emission tomography (PET) and single photon emission computerized tomography (SPECT) have also demonstrated a number of abnormalities and inconsistencies in individuals with learning disabilities, but, again, no systematic research has demonstrated specific diagnostic abnormalities. Though inroads and some consistent patterns have begun to emerge in the assessment of learning disability with the preceding technologies, a number of challenges persist with neuroimaging and neurophysiological and metabolic imaging techniques. To date, no diagnostic conclusions have been drawn utilizing these methods in the assessment of the neurobiologic basis to LD.