[previously: et al 2022] Numerous neuroimaging studies have investigated the neural basis of interindividual differences but the replicability of brain-phenotype associations remains largely unknown.
We used the UK Biobank neuroimaging dataset (n = 37,447) to examine associations with 6 variables related to physical and mental health: age, body mass index, intelligence, memory, neuroticism and alcohol consumption. We assessed the improvement of replicability for brain-phenotype associations with increasing sampling sizes [by internal subsampling].
Age may require only 300 individuals to provide highly replicable associations but other phenotypes required 1,500–3,900 individuals. The required sample size showed a negative power law relation with the estimated effect size. When only comparing the upper and lower quarters, the minimally required sample sizes for imaging decreased by 15–75%.
Our findings demonstrate that large-scale neuroimaging data are required for replicable brain-phenotype associations, that this can be mitigated by pre-selection of individuals and that small-scale studies may have reported false positive findings.
![Figure 2: Improvement of global replicability with increasing sample size. (a, d) The ICC (a) and Jaccard index (d) for CSA [cortical surface area]. (b, e) The ICC (b) and Jaccard index (e) for CT [cortical thickness]. (c, f) The ICC (c) and Jaccard index (f) for FC [functional connectivity]. The dotted lines indicate good and moderate replicability levels (0.75 and 0.5).](/doc/psychology/neuroscience/2023-liu-figure2-poweranalysiscurveofincreasingcorrelationofukbbfmribrainimagingdatawith6phenotypesagebmiintelligencenumericmemoryneuroticismalcoholobirthmonth.jpg)
(b,e) The ICC (b) and Jaccard index (e) for CT [cortical thickness].
(c,f) The ICC (c) and Jaccard index (f) for FC [functional connectivity]. The dotted lines indicate good and moderate replicability levels (0.75 and 0.5).