Cognitive processing speed and accuracy are intrinsically different in genetic architecture and brain phenotypes

Since the birth of cognitive science, researchers have used reaction time and accuracy to measure cognitive ability. The initial use of these two measures is probably a generalization from empiricism, but it also implies that most cognitive behavior has two fundamental dimensions, namely cognitive processing speed (CPS) and accuracy (CPA). In this study, we used genomic-wide association studies (GWAS) data from 14 cognitive traits to show the presence of those two factors and revealed the specific neurobiological basis underlying them. We found distinct neuroimaging signatures for CPS and CPA that white matter microstructures were predominantly associated with CPS, while cortical volumes were preferably related to CPA. We also identified specific neurobiological bases (e.g. excitatory neurons) and developmental periods (i.e. late infancy) associated with the CPS but not the CPA, suggesting the association between CPS and white matter function. Moreover, those two factors showed differential associations with other health-related traits such as screen exposure and sleep status, and a significant causal relationship with psychiatric disorders such as major depressive disorder and schizophrenia. Utilizing an independent cohort from the Adolescent Brain Cognitive Development (ABCD) study, we also uncovered the distinct contributions of those two factors on the cognitive development of young adolescents. These findings revealed two fundamental factors underlying various cognitive abilities, elucidated the distinct brain structural fingerprint and genetic architecture of CPS and CPA, and hinted at the complex interrelationship between cognitive ability, lifestyle, and mental health.