Extracting stability increases the SNP heritability of emotional problems in young people

Twin studies have shown that emotional problems (anxiety and depression) in childhood and adolescence are moderately heritable (~20-50%). In contrast, DNA-based ‘SNP heritability’ estimates are generally [ view full abstract ]

Twin studies have shown that emotional problems (anxiety and depression) in childhood and adolescence are moderately heritable (~20-50%). In contrast, DNA-based ‘SNP heritability’ estimates are generally <15% and non-significant. One notable feature of emotional problems is that they can be somewhat transient, but the moderate stability seen across time and across raters is predominantly influenced by stable genetic influences. This suggests that by capturing what is in common across time and across raters, we might be more likely to tap into any underlying genetic vulnerability. We therefore hypothesised that a phenotype capturing the pervasive stability of emotional problems would show higher heritability. We fitted single-factor latent trait models using 12 emotional problems measures across ages 7, 12 and 16, rated by parents, teachers, and children themselves in the Twins Early Development Study sample. Twin and SNP heritability estimates for stable emotional problems (N=6110 pairs and unrelated individuals, respectively) were compared to those for individual measures. Twin heritability increased from 45% on average for individual measures to 76% (se=0.023) by focusing on stable trait variance. SNP heritability rose from 5% on average (n.s.) to 14% (se=0.049; p= 0.002). Polygenic scores for both adult anxiety and depression significantly predicted variance in stable emotional problems (0.4%; p=0.0001). The variance explained was twice that in most individual measures. Stable emotional problems also showed significant genetic correlation with adult depression and anxiety (average=52%). These results demonstrate the value of examining stable emotional problems in gene-finding and prediction studies. We suggest that future genomic studies of emotional problems could benefit from adopting a lifelong approach, using measures of adult case/control status as well as childhood dimensions. We are currently testing whether these findings replicate in two other samples (NTR and TCHAD).