News Finding: Despite opposite treatments, amphetamine-liking SNPs reduced the risk for developing both diseases, suggesting that dopamine's role is more complex than hypothesized.
Paper Finding: We also found that the strength of enrichment among the discordant SNPs was slightly improved in this larger meta-analysis sample (P = 0.016) compared with the results from the PCG1 schizophrenia data.
News Context: These results provide unique genetic evidence for the role of dopamine in schizophrenia and ADHD. Despite opposite treatments, amphetamine-liking SNPs reduced the risk for developing both diseases, suggesting that dopamine's role is more complex than hypothesized. The study also offers a new direction for the analysis of a wide range of similar genetic studies, particularly ones with smaller sample sizes.
Paper Context: When considering only the Swedish schizophrenia sample, we observed borderline significant enrichment at the P ≤ 0.05 threshold (P = 0.067); when we performed the same analysis in the meta-analysis sample (PGC1 schizophrenia + Swedish schizophrenia), we found that the strength of enrichment improved (P = 0.021) compared with the same analysis in the PGC1 schizophrenia sample alone. We also found that the strength of enrichment among the discordant SNPs was slightly improved in this larger meta-analysis sample (P = 0.016) compared with the results from the PCG1 schizophrenia data. In this case, we did not observe a significant enrichment when using only the ADHD replication dataset (PGC2 ADHD); however, we did observe a nearly significant enrichment of discordant direction SNPs (P = 0.060).