Jyutika Mehta

Toxicity biomarkers in autism spectrum disorder: A blinded study of urinary porphyrins

Background:  Recent studies suggest that children diagnosed with an autism spectrum disorder (ASD) have significantly increased levels of urinary porphyrins associated with mercury (Hg) toxicity, including pentacarboxyporphyrin (5cxP), precoproporphyrin (prcP), and coproporphyrin (cP), compared to typically developing controls. However, these initial studies were criticized because the controls were not age‐ and gender‐matched to the children diagnosed with an ASD.

Toxicity biomarkers among US children compared to a similar cohort in France: A blinded study measuring urinary porphyrins

The purpose of this blinded study was to evaluate potential environmental toxicity in a cohort of neurotypical children (n = 28) living in a suburban area of north-central Texas in the United States (US) with a comparable age- and gender-matched cohort of neurotypical children (n = 28) living in a suburban area of southeastern France using urinary porphyrin testing: uroporphyrin (uP), heptacarboxyporphyrin (7cxP), hexacarboxyporphyrin (6cxP), pentacarboxyporphyrin (5cxP), precoproporphyrin (prcP), and coproporphyrin (cP). Results showed significantly elevated 6cxP, prcP (an atypical, mercury-specific porphyrin), and cP levels, and increasing trends in 5cxP levels, among neurotypical children in the USA compared to children in France. Data suggest that in US neurotypical children, there is a significantly increased body-burden of mercury (Hg) compared to the body-burden of Hg in the matched neurotypical children in France. The presence of lead contributing to the higher levels of cP also needs to be considered. Further, other factors including genetics can not be completely ruled out.

Transcranial direct current stimulation lessens dual task cost in people with Parkinson’s disease

BACKGROUND Parkinsons disease (PD) progressively impairs motor and cognitive function. Gait dysfunction in PD is exacerbated during dual task gait. Transcranial direct current stimulation (tDCS) may therapeutically benefit motor and cognitive deficits. We examined the effect of a bilateral tDCS protocol on dual task gait in people with PD. MATERIAL AND METHODS Participants with PD between 50 and 80 years received two sessions of tDCS protocol (1 active, 1 sham) separated by 7days. tDCS protocols were randomized and blinded to participants. After each tDCS protocol, participants performed single and dual task gait. Single 20-min session of bilateral tDCS (dorsolateral prefrontal cortex; left=anode, right=cathode) at 2mA and one sham session. Each participant was assessed at baseline for disease severity [Unified Parkinsons Disease Rating Scale (UPDRS)] and executive function [Repeatable Battery for the Assessment of Neuropsychological Status (RBANS)]. Following each tDCS condition (active and sham), participants performed Timed Up and Go (TUG) single and dual task conditions (TUGalone, TUGmotor, TUGcognitive) and PDQ-39. RESULTS Ten participants average age of 68.7 years (±10.2) and average PD duration average 7.9 years (±7.1) were included. The UPDRS (M=37) and RBANS (M=13%ile) were administered prior to testing. No differences were observed on dependent t-test for TUG conditions or PDQ-39. Dual task cost TUGmotor was -20.95% (tDCSactive) versus -22.58% (tDCSsham) and TUGcognitive was -25.24% (tDCSactive) versus -41.85% (tDCSsham). CONCLUSIONS Our bilateral tDCS protocol in people with PD did not significantly improve dual task gait. However, dual task cost following tDCS was lessened, most dramatically in the presence of a cognitive distractor. A larger sample size is warranted to draw further conclusions about our bilateral tDCS approach.

An exploratory study of visual sequential processing in children with cochlear implants

OBJECTIVE The objective of the study was to compare visual sequential processing in school-age children with cochlear implants (CIs) and their normal-hearing (NH) peers. Visual sequential processing was examined using both behavioral and an event-related potential (ERP) measures. METHODS Eighteen children with CIs and nineteen children who had hearing within normal limits (NH) participated in the behavioral study. Subtests from the Test of Visual Perceptual Skills and the Sensory Integration and Praxis Test were administered to all children. ERP measures were collected from five children with CI and five age-matched peers. Peak latencies (N200 and P300) and reaction times for visual sequential processing were compared in these two groups. RESULTS The findings of the study revealed significant group differences in visual sequential memory and visuo-motor sequencing tasks suggesting that children with severe-profound hearing loss may have difficulties in visual sequential tasks. The study also revealed longer P300 latencies and longer reaction times for a visual sequential matching task in children with CI when compared to their NH peers suggesting slower or delayed processing of visual sequential stimuli. CONCLUSIONS This exploratory study involving behavioral and ERP measures showed that as a group, children with prelingual, severe-profound hearing loss who use CIs have difficulties with visual sequential processing. These findings may have implications for rehabilitation for children with hearing loss in the light of recent evidence that accurate and efficient processing of sequentially presented visual stimuli is important for language and reading outcomes.

Imitation Therapy for Non-Verbal Toddlers.

When imitation skills are not present in young children, speech and language skills typically fail to emerge. There is little information on practices that foster the emergence of imitation skills in general and verbal imitation skills in particular. The present study attempted to add to our limited evidence base regarding accelerating the development of speech/language in young children who have failed to achieve expected language milestones. Imitation therapy (Zedler, 1972) was utilized for five non-verbal 18—19-month-old children to determine if imitative behavior in the form of sound production could be initiated and increased. Treatment was administered until children reached criteria for consistent imitative sound productions. Following 8—9 weeks of therapy, all five children exhibited significant increases in both the number of vocalizations and the variety of phonemes produced, and they demonstrated regular spontaneous verbal imitation and emergence of phonetically consistent forms. Imitation therapy appears to be a promising practice that merits further investigation.

Auditory-cognitive interactions underlying interaural asymmetry in an adult listener: A case study

Abstract Objective: Abnormal interaural asymmetry on tests of dichotic listening is commonly observed in individuals suspected of auditory processing disorder (APD). Although a structural basis for the abnormality has been widely accepted, the influence of cognitive variables on the degree of observed asymmetry has gained increasing attention. To study this issue, we manipulated cognitive influences on interaural asymmetry in an adult with the auditory complaints typically associated with APD. Study sample: A 55 year-old woman with complaints of difficulty understanding speech in noisy environments despite normal audiometric levels. Design: Several experimental dichotic procedures were administered. Each procedure was characterized by the manipulation of cognitive task demands. Results: Interaural asymmetry was greatest when the demands on attention and/or memory were maximal. Electrophysiological data revealed interaural asymmetry on later stages of information processing. Conclusions: Results are discussed in relation to auditory-specific outcomes on clinical tests for APD.

Variation in semantic priming across age groups: An AERP study

Abstract Objective: To study the semantic priming effect on words across the life span by means of auditory event-related potentials (AERPs). Design: Participants heard a series of three words (S1, S2, and S3). The task was to indicate whether S2 was in the same semantic category as S3. Semantic priming was quantified as the difference between AERPs to the second word when it was semantically related to the first word (S2-R) or unrelated to the first word (S2-UR). Interest was focused entirely on the processing negativity (PN) component of the AERP to S2. The purpose of S3 was to delay the task decision so that the LPC generated by the decision would not confound the measurement of the PN component to S2. Sample: Ten children (9–11 years), 11 young adults (20–30 years), and 10 seniors (60–70 years). Results: The semantic priming effect was evident in the difference between peak amplitude of the PN component of the AERP to S2R and S2UR in all three groups. Children showed a clear asymmetry favoring the left hemisphere. In young adults, the asymmetry still favored the left hemisphere, but the degree of asymmetry was less robust. In the case of seniors, the priming effect was greater over the right hemisphere. Conclusion: Results suggest that all age groups benefit from contextual support, as evidenced by the semantic priming effect. However, differences in hemispheric asymmetry of activation indicate that perhaps seniors may need to recruit additional, but somewhat different brain resources to manage otherwise largely automatic tasks.