Evidence indicates that Sickle Cell Disease (SCD) threatens neurodevelopmental outcome. Although children with SCD may be heterogeneously affected, neurocognitive impairment may already be present in toddlers. Neurocognitive functioning is an important determinant of adaptive daily life functioning later in life and is influenced by both the course of the disease and the often suboptimal environment in which afflicted children grow up. Early identification of children at the highest risk of neurocognitive impairment would enable the deployment of early interventions to mitigate the detrimental effects of SCD on the developing brain. In order to develop such interventions, a deeper understanding of the underlying pathophysiological mechanisms is required. Therefore the main aim is to study early neurocognitive functioning and development in children with SCD between the ages of 6 and 24 months old.
Objective: The main aim is to study early neurocognitive functioning and development in very young children with SCD. The secondary aims are to 1) (i) identify demographic, psychosocial and clinical determinants and (ii) identify biomarkers associated with early neurocognitive deficits in young children with SCD. 2) Analyze the association between early neurocognitive functioning and adaptive daily life functioning. Study design: Prospective observational study with an accelerated longitudinal design. The accelerated longitudinal design allows for the inclusion of children from a broad age range (6 - 24 months). During the total study period of 30 months, children can enroll in the study at the ages of 6, 12, 18 and 24 months. After enrollment, children will visit every 6 months until they reach the age of 24 months. This design spans the age range of interest in a shorter period of time and a smaller load on participants as compared to a conventional longitudinal design. Methods: Eye-tracking measurements will take place at every study visit. Demographic, psychosocial and clinical characteristics of the SCD group will be collected using prospective and structured clinical registration as part of regular clinical care. Demographic, psychosocial and clinical information of the control group will be collected using a parent questionnaire administered during the first and last study visit. Blood samples of children with SCD will be taken as part of regular blood checks at the age of 12 and/or 24 months (depending on the age of enrollment in the study). The Child Behavior Checklist, TNO AZL Preschool Children Quality of Life and the Bayley Scale of Infant and Child Development will be administered to all children at the age of 24 months. Main study parameters/endpoints: Neurocognitive functioning, as measured using eye-tracking. Secondary study parameters/ endpoints: The following determinants will be measured: Demographic, psychosocial and clinical characteristics, as measured as part of regular clinical care (SCD group) or via parent questionnaire (control group) and Biomarkers, as measured in blood (SCD group). Adaptive daily life functioning, as measured by quality of life, behavioural and emotional functioning questionnaire, and general (cognitive) development assessment.
Study Type
OBSERVATIONAL
Enrollment
93
Eye-tracking is an objective, non-invasive method and particularly suited to assess neurodevelopmental outcome in infants.
proteomics analyses methylation analyses
The strengths and difficulties questionnaire is a conventional instrument used to measure the presence of psychosocial problems, the child's strengths and the influence of psychosocial problems on daily functioning.
The TNO-AZL Preschool Children Quality of Life is a questionnaire that measures the health-related quality of life of children over the last three months
The Bayley Scale of Infant Development is a conventional instrument used to measure developmental outcome in infants
Amsterdam UMC
Amsterdam, Netherlands
Processing speed in the gap condition (Gap/Overlap task)
The speed of responding to a novel peripheral stimulus when the central stimulus disappears before the peripheral target appears. Measured as reaction time (RT) via eye-tracking in infants with sickle cell disease (SCD). Unit of Measure: Milliseconds (ms)
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Processing accuracy in the gap condition (Gap/Overlap task)
The precision of responding to a novel peripheral stimulus when the central stimulus disappears before the peripheral target appears. Measured as a binomial outcome (accurate/inaccurate) per trial via eye-tracking in infants with SCD. Unit of Measure: Proportion of accurate trials
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Orienting attention speed in the overlap condition (Gap/Overlap task)
The speed of orienting attention away from a central stimulus toward a peripheral target when the central stimulus remains on screen. Measured as RT in the overlap condition expressed as percentage change relative to mean RT in the gap condition, via eye-tracking in infants with SCD. Unit of Measure: Percentage (%)
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Orienting attention accuracy in the overlap condition (Gap/Overlap task)
The precision of orienting attention toward a peripheral target when the central stimulus remains on screen. Measured as a binomial outcome (accurate/inaccurate) per trial via eye-tracking in infants with SCD. Unit of Measure: Proportion of accurate trials
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Alerting attention without external cues (Gap/Overlap task)
The ability to maintain focus on the task without external attention-grabbing cues. Measured as a binomial outcome per trial (completed without attention grabber: yes/no) via eye-tracking in infants with SCD. Unit of Measure: Proportion of trials completed without attention grabber
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Sustained attention across trials (Gap/Overlap task)
The ability to attend to the task over a longer period. Measured as the number of trials completed expressed as a percentage of the total possible trials, via eye-tracking in infants with SCD. Unit of Measure: Percentage (%)
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Fixation duration during free viewing (Freeview task)
The amount of time the eyes remain stably focused on a specific location, defined as periods of stable gaze between successive saccades. Measured as mean fixation duration via eye-tracking in infants with SCD. Unit of Measure: Milliseconds (ms)
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Habituation (Habituation task)
The process of becoming accustomed to a repeatedly presented stimulus. Measured as the number of trials required to reach the pre-defined habituation criterion via eye-tracking in infants with SCD. Unit of Measure: Number of trials
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Recognition (Habituation task)
The ability to distinguish a previously presented stimulus from a novel one. Measured as the absolute difference in looking time toward the habituation stimulus versus the novel stimulus, via eye-tracking in infants with SCD. Unit of Measure: Percentage (%)
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Novelty preference (Habituation task)
The tendency to inspect a novel stimulus relative to a previously presented one. Measured as looking time toward the novel stimulus as a percentage of total looking time, via eye-tracking in infants with SCD. Unit of Measure: Percentage (%)
Time frame: T1 (age 6 months), T2 (age 12 months), T3 (age 18 months), T4 (age 24 months)
Demographic and perinatal characteristics assessed via parent-reported questionnaire
Demographic and perinatal information collected via a structured parent/caretaker questionnaire, including child age, sex, ethnicity, country of origin, parental education level (as proxy for socioeconomic status), and perinatal information (e.g. breastfeeding, birth characteristics). Clinical characteristics (e.g. SCD genotype, disease severity, treatment) are extracted from electronic health records. Unit of Measure: Categorical and continuous variables (reported descriptively)
Time frame: At study visit of 6, 12 18 or 24 months of age, depending on the enrollment age. The first visit in the study
Behavioral and emotional functioning assessed using the Strengths and Difficulties Questionnaire (SDQ)
Parent-reported behavioral and emotional functioning measured using the SDQ, a validated screening instrument. The SDQ assesses five domains: emotional symptoms, conduct problems, hyperactivity/inattention, peer relationship problems, and prosocial behavior. Scores are reported per subscale and as a total difficulties score. Unit of Measure: Scale score (0-40 total difficulties score)
Time frame: study visit at 24 months of age
Development assessed using the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III)
Standardized assessment of development administered by a trained examiner at age 24 months using the BSID-III (Cognitive and Motor Scale). Scores are reported as scaled scores with a normative mean of 10 (SD=3). Unit of Measure: Scaled score
Time frame: study visit at 24 months of age
Plasma proteomic biomarker profile assessed via blood sample in children with SCD
A blood sample is collected from children with SCD to identify plasma proteomic biomarkers related to disease severity and neurological functioning. Samples are analyzed using unbiased proteomics analyses to characterize protein expression profiles. Unit of Measure: Protein expression levels (reported as relative abundance)
Time frame: study visit at 12 months of age and study visit at 24 months of age
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