Aisha Dickerson | The University of Texas Health Science Center at Houston (original) (raw)

Papers by Aisha Dickerson

Research paper thumbnail of Synergic effect of GSTP1 and blood manganese concentrations in Autism Spectrum Disorder

Research in autism spectrum disorders, 2015

We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to inv... more We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to investigate whether there is an interaction between glutathione-S-transferase (GST) genes and blood manganese concentrations (BMC) in relation to Autism Spectrum Disorder (ASD). Our findings, indicate that among children who had the Ile/Ile genotype for GST pi 1 (GSTP1), those with BMC ≥ 12µg/L had about 4 times higher odds of ASD than those with BMC < 12µg/L, (P=0.03) under a co-dominant genetic model. After adjusting for potential confounders, among the subgroup of children with genotype Ile/Ile, those with BMC ≥ 12µg/L had about six times higher odds of ASD than those with BMC < 12µg/L, (P=0.04). The results were similar when a recessive genetic model was used. These findings suggest a possible synergic effect of BMC and GSTP1 in ASD. Since our analysis included a variety of genetic models and was not adjusted for multiple testing, replication in other populations is warranted.

Research paper thumbnail of Synergic effect of GSTP1 and blood manganese concentrations in Autism Spectrum Disorder

Research in Autism Spectrum Disorders, 2015

We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to inv... more We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to investigate whether there is an interaction between glutathione-S-transferase (GST) genes and blood manganese concentrations (BMC) in relation to Autism Spectrum Disorder (ASD). Our findings, indicate that among children who had the Ile/Ile genotype for GST pi 1 (GSTP1), those with BMC ≥ 12µg/L had about 4 times higher odds of ASD than those with BMC &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 12µg/L, (P=0.03) under a co-dominant genetic model. After adjusting for potential confounders, among the subgroup of children with genotype Ile/Ile, those with BMC ≥ 12µg/L had about six times higher odds of ASD than those with BMC &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 12µg/L, (P=0.04). The results were similar when a recessive genetic model was used. These findings suggest a possible synergic effect of BMC and GSTP1 in ASD. Since our analysis included a variety of genetic models and was not adjusted for multiple testing, replication in other populations is warranted.

Research paper thumbnail of Methodological issues for designing and conducting a multicenter, international clinical trial in Acute Stroke: Experience from ARTSS-2 trial

Contemporary Clinical Trials, 2015

We describe innovations in the study design and the efficient data coordination of a randomized m... more We describe innovations in the study design and the efficient data coordination of a randomized multicenter trial of Argatroban in Combination with Recombinant Tissue Plasminogen Activator for Acute Stroke (ARTSS-2). ARTSS-2 is a 3-arm, multisite/multiregional randomized controlled trials (RCTs) of two doses of Argatroban injection (low, high) in combination with recombinant tissue plasminogen activator (rt-PA) in acute ischemic stroke patients and rt-PA alone. We developed a covariate adaptive randomization program that balanced the study arms with respect to study site as well as hemorrhage after thrombolysis (HAT) score and presence of distal internal carotid artery occlusion (DICAO). We used simulation studies to validate performance of the randomization program before making any adaptations during the trial. For the first 90 patients enrolled in ARTSS-2, we evaluated performance of our randomization program using chi-square tests of homogeneity or extended Fisher&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s exact test. We also designed a four-step partly Bayesian safety stopping rule for low and high dose Argatroban arms. Homogeneity of the study arms was confirmed with respect to distribution of study site (UK sites vs. US sites, P=0.98), HAT score (0-2 vs. 3-5, P =1.0), and DICAO (N/A vs. No vs. Yes, P=0.97). Our stopping thresholds for safety of low and high dose Argatroban were not crossed. Despite challenges, data quality was assured. We recommend adaptive designs for randomization and Bayesian safety stopping rules for multisite phase I/II RCTs for maintaining additional flexibility. Efficient data coordination could lead to improved data quality.

Research paper thumbnail of Autism spectrum disorder prevalence and proximity to industrial facilities releasing arsenic, lead or mercury

Science of The Total Environment, 2015

Prenatal and perinatal exposures to air pollutants have been shown to adversely affect birth outc... more Prenatal and perinatal exposures to air pollutants have been shown to adversely affect birth outcomes in offspring and may contribute to prevalence of autism spectrum disorder (ASD). For this ecologic study, we evaluated the association between ASD prevalence, at the census tract level, and proximity of tract centroids to the closest industrial facilities releasing arsenic, lead or mercury during the 1990s. We used 2000 to 2008 surveillance data from five sites of the Autism and Developmental Disabilities Monitoring (ADDM) network and 2000 census data to estimate prevalence. Multi-level negative binomial regression models were used to test associations between ASD prevalence and proximity to industrial facilities in existence from 1991 to 1999 according to the US Environmental Protection Agency Toxics Release Inventory (USEPA-TRI). Data for 2489 census tracts showed that after adjustment for demographic and socio-economic area-based characteristics, ASD prevalence was higher in census tracts located in the closest 10th percentile compared of distance to those in the furthest 50th percentile (adjusted RR=1.27, 95% CI: (1.00, 1.61), P=0.049). The findings observed in this study are suggestive of the association between urban residential proximity to industrial facilities emitting air pollutants and higher ASD prevalence.

Research paper thumbnail of Waiver of consent in noninterventional, observational emergency research: the PROMMTT experience

The journal of trauma and acute care surgery, 2013

In the PRospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study, waiver of ... more In the PRospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study, waiver of consent was used because previous literature reported low response rates and subsequent bias. The goal of this article was to examine the rationale and tradeoffs of using waiver of consent in PROMMTT. PROMMTT enrolled trauma patients receiving at least 1 U of red blood cells within 6 hours after admission at 10 US Level 1 trauma centers. Local institutional review boards (IRBs) from all sites approved the study. Site 8 was required by their IRB to attempt consent but was allowed to retain data on patients unable to be consented. Of 121 subjects enrolled at Site 8, 55 consents were obtained (46%), and no patient or legally authorized representative refused to give consent. Of the patients, 36 (30%) died, and 6 (5%) were discharged before consent could be attempted. Consent was attempted but not possible among 24 patients (20%). Of the 10 clinical sites, 6 of the local IRBs approved collec...

Research paper thumbnail of Concentration of Lead, Mercury, Cadmium, Aluminum, Arsenic and Manganese in Umbilical Cord Blood of Jamaican Newborns

International Journal of Environmental Research and Public Health, 2015

The objective of this study was to characterize the concentrations of lead, mercury, cadmium, alu... more The objective of this study was to characterize the concentrations of lead, mercury, cadmium, aluminum, and manganese in umbilical cord blood of Jamaican newborns and to explore the possible association between concentrations of these elements and certain birth outcomes. Based on data from 100 pregnant mothers and their 100 newborns who were enrolled from Jamaica in 2011, the arithmetic mean (standard deviation) concentrations of cord blood lead, mercury, aluminum, and manganese were 0.8 (1.3 μg/dL), 4.4 (2.4 μg/L), 10.9 (9.2 μg/L), and 43.7 (17.7 μg/L), respectively. In univariable General Linear Models, the geometric mean cord blood aluminum concentration was higher for children whose mothers had completed their education up to high school compared to those whose mothers had any education beyond high school (12.2 μg/L vs. 6.4 μg/L; p < 0.01). After controlling for maternal education level and socioeconomic status (through ownership of a family car), the cord blood lead concentration was significantly associated with head circumference (adjusted p < 0.01). Our results not only provide levels of arsenic and the aforementioned metals in cord blood that could serve as a reference for the Jamaican population, but also replicate previously reported significant associations between cord blood lead concentrations and head circumference at birth in other populations.

Research paper thumbnail of Role of parental occupation in autism spectrum disorder diagnosis and severity

Research in Autism Spectrum Disorders, 2014

Research paper thumbnail of Interaction between GSTT1 and GSTP1 allele variants as a risk modulating-factor for autism spectrum disorders

Research in Autism Spectrum Disorders, 2015

We investigated the role of glutathione S-transferase (GST) genes in Autism Spectrum Disorder (AS... more We investigated the role of glutathione S-transferase (GST) genes in Autism Spectrum Disorder (ASD). We used data from 111 pairs of age- and sex-matched ASD cases and typically developing (TD) controls between 2-8 years of age from Jamaica to investigate the role of GST pi 1 (GSTP1), GST theta 1 (GSTT1), and GST mu 1 (GSTM1) polymorphisms in susceptibility to ASD. In univariable conditional logistic regression models we did not observe significant associations between ASD status and GSTT1, GSTM1, or GSTP1 genotype (all P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.15). However, in multivariable conditional logistic regression models, we identified a significant interaction between GSTP1 and GSTT1 in relation to ASD. Specifically, in children heterozygous for the GSTP1 Ile105Val polymorphism, the odds of ASD was significantly higher in those with the null GSTT1 genotype than those with the other genotypes [Matched Odds Ratio (MOR) = 2.97, 95% CI (1.09, 8.01), P = 0.03]. Replication in other populations is warranted.

Research paper thumbnail of Role of fruits, grains, and seafood consumption in blood cadmium concentrations of Jamaican children with and without Autism Spectrum Disorder

Research in Autism Spectrum Disorders, 2014

Human exposure to cadmium has adverse effects on the nervous system. Utilizing data from 110 age-... more Human exposure to cadmium has adverse effects on the nervous system. Utilizing data from 110 age-and sex-matched case-control pairs (220 children) ages 2-8 years in Kingston, Jamaica, we compared the 75th percentile of blood cadmium concentrations in children with and without Autism Spectrum Disorder (ASD). In both univariable and multivariable Quantile Regression Models that controlled for potential confounding factors, we did not find any significant differences between ASD cases and typically developing (TD) controls with respect to the 75th percentile of blood cadmium concentrations (P > 0.22). However, we found a significantly higher 75th percentile of blood cadmium concentrations in TD Jamaican children who consumed shellfish (lobsters, crabs) (P < 0.05), fried plantain (P < 0.01), and boiled dumpling (P < 0.01). We also observed that children living in Jamaica have an arithmetic mean blood cadmium concentration of 0.16 mg/L which is similar to that of the children in developed countries and much lower than that of children in developing countries. Although our results do not support an association between blood cadmium concentrations and ASD, to our knowledge, this study is the first to report levels of blood cadmium in TD children as well as those with ASD in Jamaica. ß

Research paper thumbnail of Blood Lead Concentrations in Jamaican Children with and without Autism Spectrum Disorder

International Journal of Environmental Research and Public Health, 2014

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder manifesting by early childhood. L... more Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder manifesting by early childhood. Lead is a toxic metal shown to cause neurodevelopmental disorders in children. Several studies have investigated the possible association between exposure to lead and ASD, but their findings are conflicting. Using data from 100 ASD cases (2-8 years of age) and their age-and sex-matched typically developing controls, we investigated the association between blood lead concentrations (BLC) and ASD in Jamaican children. We administered a questionnaire to assess demographic and socioeconomic information as well as exposure to potential lead sources. We used General Linear Models (GLM) to assess the association of BLC with ASD status as well as with sources of exposure to lead. In univariable GLM, we found a significant difference between geometric mean blood lead concentrations of ASD cases and controls (2.25 μg/dL cases vs. 2.73 μg/dL controls, p < 0.05). However, after controlling for potential confounders, there were no significant differences between adjusted geometric mean blood lead concentrations of ASD cases and controls (2.55 μg/dL vs. 2.72 μg/dL, p = 0.64). Our results do not support an association between BLC and ASD in Jamaican children. We have identified significant confounders when assessing an association between ASD and BLC.

Research paper thumbnail of Role of Metabolic Genes in Blood Arsenic Concentrations of Jamaican Children with and without Autism Spectrum Disorder

International Journal of Environmental Research and Public Health, 2014

Arsenic is a toxic metalloid with known adverse effects on human health. Glutathione-S-transferas... more Arsenic is a toxic metalloid with known adverse effects on human health. Glutathione-S-transferase (GST) genes, including GSTT1, GSTP1, and GSTM1, play a major role in detoxification and metabolism of xenobiotics. We investigated the association between GST genotypes and whole blood arsenic concentrations (BASC) in Jamaican children with and without autism spectrum disorder (ASD). We used data from 100 ASD cases and their 1:1 age-and sex-matched typically developing (TD) controls (age 2-8 years) from Jamaica. Using log-transformed BASC as the dependent variable in a General Linear Model, we observed a significant interaction between GSTP1 and ASD case status while controlling for several confounding variables. However, for GSTT1 and GSTM1 we did not observe any significant associations with BASC. Our findings indicate that TD children who had the Ile/Ile or Ile/Val genotype for GSTP1 had a significantly higher geometric mean BASC than those with genotype Val/Val (3.67 µg/L vs. 2.69 µg/L, p < 0.01). Although, among the ASD cases, this difference was not statistically significant, the direction of the observed difference was consistent with that of the TD control children. These findings suggest a possible role of GSTP1 in the detoxification of arsenic.

Research paper thumbnail of The role of drinking water sources, consumption of vegetables and seafood in relation to blood arsenic concentrations of Jamaican children with and without Autism Spectrum Disorders

Science of The Total Environment, 2012

Arsenic is a toxic metal with harmful effects on human health, particularly on cognitive function... more Arsenic is a toxic metal with harmful effects on human health, particularly on cognitive function. Autism Spectrum Disorders (ASDs) are lifelong neurodevelopmental and behavioral disorders manifesting in infancy or early childhood. We used data from 130 children between 2-8 years (65 pairs of ASD cases with age-and sex-matched control), to compare the mean total blood arsenic concentrations in children with and without ASDs in Kingston, Jamaica. Based on univariable analysis, we observed a significant difference between ASD cases and controls (4.03μg/L for cases vs. 4.48μg/L for controls, P < 0.01). In the final multivariable General Linear Model (GLM), after controlling for car ownership, maternal age, parental education levels, source of drinking water, consumption of "yam, sweet potato, or dasheen", "carrot or pumpkin", "callaloo, broccoli, or pak choi", cabbage, avocado, and the frequency of seafood consumption per week, we did not find a significant association between blood arsenic concentrations and ASD status (4.36μg/L for cases vs. 4.65μg/L for controls, P = 0.23). Likewise, in a separate final multivariable GLM, we found that source of drinking water, eating avocado, and eating "callaloo, broccoli, or pak choi" were significantly associated with higher blood arsenic concentrations (all three P < 0.05). Based on our findings, we recommend assessment of arsenic levels in water, fruits, and vegetables, as well as increased awareness among the Jamaican population regarding potential risks for various exposures to arsenic.

Research paper thumbnail of Factors associated with blood lead concentrations of children in Jamaica

Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering, Jan 12, 2015

Lead is a heavy metal known to be detrimental to neurologic, physiologic, and behavioral health o... more Lead is a heavy metal known to be detrimental to neurologic, physiologic, and behavioral health of children. Previous studies from Jamaica reported that mean lead levels in soil are four times that of lead levels in some other parts of the world. Other studies detected lead levels in fruits and root vegetables, which were grown in areas with lead contaminated soil. In this study, we investigate environmental factors associated with blood lead concentrations in Jamaican children. The participants in this study comprised 125 typically developing (TD) children (ages 2-8 years) who served as controls in an age- and sex-matched case-control study that enrolled children from 2009-2012 in Jamaica. We administered a questionnaire to assess demographic and socioeconomic information as well as potential exposures to lead through food. Using General Linear Models (GLMs), we identified factors associated with blood lead concentrations in Jamaican children. The geometric mean blood lead concentr...

Research paper thumbnail of Synergic effect of GSTP1 and blood manganese concentrations in Autism Spectrum Disorder

Research in autism spectrum disorders, 2015

We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to inv... more We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to investigate whether there is an interaction between glutathione-S-transferase (GST) genes and blood manganese concentrations (BMC) in relation to Autism Spectrum Disorder (ASD). Our findings, indicate that among children who had the Ile/Ile genotype for GST pi 1 (GSTP1), those with BMC ≥ 12µg/L had about 4 times higher odds of ASD than those with BMC < 12µg/L, (P=0.03) under a co-dominant genetic model. After adjusting for potential confounders, among the subgroup of children with genotype Ile/Ile, those with BMC ≥ 12µg/L had about six times higher odds of ASD than those with BMC < 12µg/L, (P=0.04). The results were similar when a recessive genetic model was used. These findings suggest a possible synergic effect of BMC and GSTP1 in ASD. Since our analysis included a variety of genetic models and was not adjusted for multiple testing, replication in other populations is warranted.

Research paper thumbnail of Synergic effect of GSTP1 and blood manganese concentrations in Autism Spectrum Disorder

Research in Autism Spectrum Disorders, 2015

We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to inv... more We used data from 100 age- and sex-matched case-control pairs (age 2-8 years) from Jamaica to investigate whether there is an interaction between glutathione-S-transferase (GST) genes and blood manganese concentrations (BMC) in relation to Autism Spectrum Disorder (ASD). Our findings, indicate that among children who had the Ile/Ile genotype for GST pi 1 (GSTP1), those with BMC ≥ 12µg/L had about 4 times higher odds of ASD than those with BMC &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 12µg/L, (P=0.03) under a co-dominant genetic model. After adjusting for potential confounders, among the subgroup of children with genotype Ile/Ile, those with BMC ≥ 12µg/L had about six times higher odds of ASD than those with BMC &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 12µg/L, (P=0.04). The results were similar when a recessive genetic model was used. These findings suggest a possible synergic effect of BMC and GSTP1 in ASD. Since our analysis included a variety of genetic models and was not adjusted for multiple testing, replication in other populations is warranted.

Research paper thumbnail of Methodological issues for designing and conducting a multicenter, international clinical trial in Acute Stroke: Experience from ARTSS-2 trial

Contemporary Clinical Trials, 2015

We describe innovations in the study design and the efficient data coordination of a randomized m... more We describe innovations in the study design and the efficient data coordination of a randomized multicenter trial of Argatroban in Combination with Recombinant Tissue Plasminogen Activator for Acute Stroke (ARTSS-2). ARTSS-2 is a 3-arm, multisite/multiregional randomized controlled trials (RCTs) of two doses of Argatroban injection (low, high) in combination with recombinant tissue plasminogen activator (rt-PA) in acute ischemic stroke patients and rt-PA alone. We developed a covariate adaptive randomization program that balanced the study arms with respect to study site as well as hemorrhage after thrombolysis (HAT) score and presence of distal internal carotid artery occlusion (DICAO). We used simulation studies to validate performance of the randomization program before making any adaptations during the trial. For the first 90 patients enrolled in ARTSS-2, we evaluated performance of our randomization program using chi-square tests of homogeneity or extended Fisher&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s exact test. We also designed a four-step partly Bayesian safety stopping rule for low and high dose Argatroban arms. Homogeneity of the study arms was confirmed with respect to distribution of study site (UK sites vs. US sites, P=0.98), HAT score (0-2 vs. 3-5, P =1.0), and DICAO (N/A vs. No vs. Yes, P=0.97). Our stopping thresholds for safety of low and high dose Argatroban were not crossed. Despite challenges, data quality was assured. We recommend adaptive designs for randomization and Bayesian safety stopping rules for multisite phase I/II RCTs for maintaining additional flexibility. Efficient data coordination could lead to improved data quality.

Research paper thumbnail of Autism spectrum disorder prevalence and proximity to industrial facilities releasing arsenic, lead or mercury

Science of The Total Environment, 2015

Prenatal and perinatal exposures to air pollutants have been shown to adversely affect birth outc... more Prenatal and perinatal exposures to air pollutants have been shown to adversely affect birth outcomes in offspring and may contribute to prevalence of autism spectrum disorder (ASD). For this ecologic study, we evaluated the association between ASD prevalence, at the census tract level, and proximity of tract centroids to the closest industrial facilities releasing arsenic, lead or mercury during the 1990s. We used 2000 to 2008 surveillance data from five sites of the Autism and Developmental Disabilities Monitoring (ADDM) network and 2000 census data to estimate prevalence. Multi-level negative binomial regression models were used to test associations between ASD prevalence and proximity to industrial facilities in existence from 1991 to 1999 according to the US Environmental Protection Agency Toxics Release Inventory (USEPA-TRI). Data for 2489 census tracts showed that after adjustment for demographic and socio-economic area-based characteristics, ASD prevalence was higher in census tracts located in the closest 10th percentile compared of distance to those in the furthest 50th percentile (adjusted RR=1.27, 95% CI: (1.00, 1.61), P=0.049). The findings observed in this study are suggestive of the association between urban residential proximity to industrial facilities emitting air pollutants and higher ASD prevalence.

Research paper thumbnail of Waiver of consent in noninterventional, observational emergency research: the PROMMTT experience

The journal of trauma and acute care surgery, 2013

In the PRospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study, waiver of ... more In the PRospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study, waiver of consent was used because previous literature reported low response rates and subsequent bias. The goal of this article was to examine the rationale and tradeoffs of using waiver of consent in PROMMTT. PROMMTT enrolled trauma patients receiving at least 1 U of red blood cells within 6 hours after admission at 10 US Level 1 trauma centers. Local institutional review boards (IRBs) from all sites approved the study. Site 8 was required by their IRB to attempt consent but was allowed to retain data on patients unable to be consented. Of 121 subjects enrolled at Site 8, 55 consents were obtained (46%), and no patient or legally authorized representative refused to give consent. Of the patients, 36 (30%) died, and 6 (5%) were discharged before consent could be attempted. Consent was attempted but not possible among 24 patients (20%). Of the 10 clinical sites, 6 of the local IRBs approved collec...

Research paper thumbnail of Concentration of Lead, Mercury, Cadmium, Aluminum, Arsenic and Manganese in Umbilical Cord Blood of Jamaican Newborns

International Journal of Environmental Research and Public Health, 2015

The objective of this study was to characterize the concentrations of lead, mercury, cadmium, alu... more The objective of this study was to characterize the concentrations of lead, mercury, cadmium, aluminum, and manganese in umbilical cord blood of Jamaican newborns and to explore the possible association between concentrations of these elements and certain birth outcomes. Based on data from 100 pregnant mothers and their 100 newborns who were enrolled from Jamaica in 2011, the arithmetic mean (standard deviation) concentrations of cord blood lead, mercury, aluminum, and manganese were 0.8 (1.3 μg/dL), 4.4 (2.4 μg/L), 10.9 (9.2 μg/L), and 43.7 (17.7 μg/L), respectively. In univariable General Linear Models, the geometric mean cord blood aluminum concentration was higher for children whose mothers had completed their education up to high school compared to those whose mothers had any education beyond high school (12.2 μg/L vs. 6.4 μg/L; p < 0.01). After controlling for maternal education level and socioeconomic status (through ownership of a family car), the cord blood lead concentration was significantly associated with head circumference (adjusted p < 0.01). Our results not only provide levels of arsenic and the aforementioned metals in cord blood that could serve as a reference for the Jamaican population, but also replicate previously reported significant associations between cord blood lead concentrations and head circumference at birth in other populations.

Research paper thumbnail of Role of parental occupation in autism spectrum disorder diagnosis and severity

Research in Autism Spectrum Disorders, 2014

Research paper thumbnail of Interaction between GSTT1 and GSTP1 allele variants as a risk modulating-factor for autism spectrum disorders

Research in Autism Spectrum Disorders, 2015

We investigated the role of glutathione S-transferase (GST) genes in Autism Spectrum Disorder (AS... more We investigated the role of glutathione S-transferase (GST) genes in Autism Spectrum Disorder (ASD). We used data from 111 pairs of age- and sex-matched ASD cases and typically developing (TD) controls between 2-8 years of age from Jamaica to investigate the role of GST pi 1 (GSTP1), GST theta 1 (GSTT1), and GST mu 1 (GSTM1) polymorphisms in susceptibility to ASD. In univariable conditional logistic regression models we did not observe significant associations between ASD status and GSTT1, GSTM1, or GSTP1 genotype (all P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.15). However, in multivariable conditional logistic regression models, we identified a significant interaction between GSTP1 and GSTT1 in relation to ASD. Specifically, in children heterozygous for the GSTP1 Ile105Val polymorphism, the odds of ASD was significantly higher in those with the null GSTT1 genotype than those with the other genotypes [Matched Odds Ratio (MOR) = 2.97, 95% CI (1.09, 8.01), P = 0.03]. Replication in other populations is warranted.

Research paper thumbnail of Role of fruits, grains, and seafood consumption in blood cadmium concentrations of Jamaican children with and without Autism Spectrum Disorder

Research in Autism Spectrum Disorders, 2014

Human exposure to cadmium has adverse effects on the nervous system. Utilizing data from 110 age-... more Human exposure to cadmium has adverse effects on the nervous system. Utilizing data from 110 age-and sex-matched case-control pairs (220 children) ages 2-8 years in Kingston, Jamaica, we compared the 75th percentile of blood cadmium concentrations in children with and without Autism Spectrum Disorder (ASD). In both univariable and multivariable Quantile Regression Models that controlled for potential confounding factors, we did not find any significant differences between ASD cases and typically developing (TD) controls with respect to the 75th percentile of blood cadmium concentrations (P > 0.22). However, we found a significantly higher 75th percentile of blood cadmium concentrations in TD Jamaican children who consumed shellfish (lobsters, crabs) (P < 0.05), fried plantain (P < 0.01), and boiled dumpling (P < 0.01). We also observed that children living in Jamaica have an arithmetic mean blood cadmium concentration of 0.16 mg/L which is similar to that of the children in developed countries and much lower than that of children in developing countries. Although our results do not support an association between blood cadmium concentrations and ASD, to our knowledge, this study is the first to report levels of blood cadmium in TD children as well as those with ASD in Jamaica. ß

Research paper thumbnail of Blood Lead Concentrations in Jamaican Children with and without Autism Spectrum Disorder

International Journal of Environmental Research and Public Health, 2014

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder manifesting by early childhood. L... more Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder manifesting by early childhood. Lead is a toxic metal shown to cause neurodevelopmental disorders in children. Several studies have investigated the possible association between exposure to lead and ASD, but their findings are conflicting. Using data from 100 ASD cases (2-8 years of age) and their age-and sex-matched typically developing controls, we investigated the association between blood lead concentrations (BLC) and ASD in Jamaican children. We administered a questionnaire to assess demographic and socioeconomic information as well as exposure to potential lead sources. We used General Linear Models (GLM) to assess the association of BLC with ASD status as well as with sources of exposure to lead. In univariable GLM, we found a significant difference between geometric mean blood lead concentrations of ASD cases and controls (2.25 μg/dL cases vs. 2.73 μg/dL controls, p < 0.05). However, after controlling for potential confounders, there were no significant differences between adjusted geometric mean blood lead concentrations of ASD cases and controls (2.55 μg/dL vs. 2.72 μg/dL, p = 0.64). Our results do not support an association between BLC and ASD in Jamaican children. We have identified significant confounders when assessing an association between ASD and BLC.

Research paper thumbnail of Role of Metabolic Genes in Blood Arsenic Concentrations of Jamaican Children with and without Autism Spectrum Disorder

International Journal of Environmental Research and Public Health, 2014

Arsenic is a toxic metalloid with known adverse effects on human health. Glutathione-S-transferas... more Arsenic is a toxic metalloid with known adverse effects on human health. Glutathione-S-transferase (GST) genes, including GSTT1, GSTP1, and GSTM1, play a major role in detoxification and metabolism of xenobiotics. We investigated the association between GST genotypes and whole blood arsenic concentrations (BASC) in Jamaican children with and without autism spectrum disorder (ASD). We used data from 100 ASD cases and their 1:1 age-and sex-matched typically developing (TD) controls (age 2-8 years) from Jamaica. Using log-transformed BASC as the dependent variable in a General Linear Model, we observed a significant interaction between GSTP1 and ASD case status while controlling for several confounding variables. However, for GSTT1 and GSTM1 we did not observe any significant associations with BASC. Our findings indicate that TD children who had the Ile/Ile or Ile/Val genotype for GSTP1 had a significantly higher geometric mean BASC than those with genotype Val/Val (3.67 µg/L vs. 2.69 µg/L, p < 0.01). Although, among the ASD cases, this difference was not statistically significant, the direction of the observed difference was consistent with that of the TD control children. These findings suggest a possible role of GSTP1 in the detoxification of arsenic.

Research paper thumbnail of The role of drinking water sources, consumption of vegetables and seafood in relation to blood arsenic concentrations of Jamaican children with and without Autism Spectrum Disorders

Science of The Total Environment, 2012

Arsenic is a toxic metal with harmful effects on human health, particularly on cognitive function... more Arsenic is a toxic metal with harmful effects on human health, particularly on cognitive function. Autism Spectrum Disorders (ASDs) are lifelong neurodevelopmental and behavioral disorders manifesting in infancy or early childhood. We used data from 130 children between 2-8 years (65 pairs of ASD cases with age-and sex-matched control), to compare the mean total blood arsenic concentrations in children with and without ASDs in Kingston, Jamaica. Based on univariable analysis, we observed a significant difference between ASD cases and controls (4.03μg/L for cases vs. 4.48μg/L for controls, P < 0.01). In the final multivariable General Linear Model (GLM), after controlling for car ownership, maternal age, parental education levels, source of drinking water, consumption of "yam, sweet potato, or dasheen", "carrot or pumpkin", "callaloo, broccoli, or pak choi", cabbage, avocado, and the frequency of seafood consumption per week, we did not find a significant association between blood arsenic concentrations and ASD status (4.36μg/L for cases vs. 4.65μg/L for controls, P = 0.23). Likewise, in a separate final multivariable GLM, we found that source of drinking water, eating avocado, and eating "callaloo, broccoli, or pak choi" were significantly associated with higher blood arsenic concentrations (all three P < 0.05). Based on our findings, we recommend assessment of arsenic levels in water, fruits, and vegetables, as well as increased awareness among the Jamaican population regarding potential risks for various exposures to arsenic.

Research paper thumbnail of Factors associated with blood lead concentrations of children in Jamaica

Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering, Jan 12, 2015

Lead is a heavy metal known to be detrimental to neurologic, physiologic, and behavioral health o... more Lead is a heavy metal known to be detrimental to neurologic, physiologic, and behavioral health of children. Previous studies from Jamaica reported that mean lead levels in soil are four times that of lead levels in some other parts of the world. Other studies detected lead levels in fruits and root vegetables, which were grown in areas with lead contaminated soil. In this study, we investigate environmental factors associated with blood lead concentrations in Jamaican children. The participants in this study comprised 125 typically developing (TD) children (ages 2-8 years) who served as controls in an age- and sex-matched case-control study that enrolled children from 2009-2012 in Jamaica. We administered a questionnaire to assess demographic and socioeconomic information as well as potential exposures to lead through food. Using General Linear Models (GLMs), we identified factors associated with blood lead concentrations in Jamaican children. The geometric mean blood lead concentr...