Meta-analysis Report
Basic Info
| Reference |
Nikolaidis A, 201020019071
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| Citation |
Nikolaidis A. and Gray J. R. (2010) "ADHD and the DRD4 exon III 7-repeat polymorphism: an international meta-analysis." Soc Cogn Affect Neurosci, 5(2-3): 188-93.
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| Study Type |
Candidate association study |
| Summary |
They sought to elucidate the relationship of ADHD (Attention-Deficit Hyperactivity Disorder) to the DRD4 exon III VNTR 7R allele worldwide using analytic techniques and to relate these findings to the field of cultural neuroscience. To focus on a potential moderating role of race/ethnicity, they excluded over 30 papers that have explored the relationship between the DRD4 7R and ADHD but had unclear or lax racial-ethnic inclusion criteria. The papers in this meta-analysis were only included if a single race made up 95% or more of their sample. They searched for and translated papers not published in English, and found a significant difference in the relationship of ADHD and DRD4 7R in people of European-Caucasian and South American descent vs people of Middle Eastern ancestry. They also examined the moderating effect of differing ADHD diagnoses, subject recruitment, control recruitment and male to female ratio. Finally, they consider the implications of these data for cultural neuroscience. |
Detail Info
| Samples |
They identified papers related to ADHD and DRD4 by searching through papers available on PubMed and Google Scholar, and by searching through meta analyses already written on the topic of ADHD and DRD4. They then narrowed the search by selecting papers that were directly related to the 7 repeat DRD4 allele (exon III VNTR). From over 3200 papers retrieved from PubMed and Google Scholar, they retained 600 abstracts on topics related to DRD4 and ADHD. Of these, they identified 61 papers relating directly to DRD4 7R and ADHD and 24 needing translation. Since the 7R allele is highly variant among races (Chang et al., 1996), they decided to include papers with 95% or greater racial homogeneity. All of the 23 papers included in the final analyses were published in journals. |
| Statistic Method |
These data were analyzed using Comprehensive Meta-analysis (Biostat, 2005), a software program that can compute a large variety of meta analytical statistics, and used it to compute all statistics. I squared is a test for percentage of variability between studies due to heterogeneity of the studies themselves rather than sampling error. |
| Basic Result |
There is a significant difference in the relationship of ADHD and DRD4 7R in people of European-Caucasian and South American descent vs people of Middle Eastern ancestry. |
Genes reported by this study: 1
| Gene |
Statistical Values/Author Comments |
Result of Statistical Analysis |
| DRD4 |
the Caucasian group showed a positive relationship between A......
the Caucasian group showed a positive relationship between ADHD and the DRD4 7R allele; the Middle Eastern group showed a negative relationship between ADHD and the DRD4 7R allele; The South American group also demonstrated a positive relationship between ADHD and the DRD4 7R allele; The Asian group demonstrated a positive relationship between the DRD4 2R allele and ADHD, but the results were insignificant
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Significant
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