Abstract
Brain age prediction is a relatively new tool in neuro-medicine and the neurosciences. In research and clinical practice, it finds multiple use as a marker for biological age, for general health status of the brain and as an indicator for several brain-based disorders. Its utility in all these tasks depends on detecting outliers and thus failing to correctly predict chronological age. The indicative value of brain age prediction is generated by the gap between a brain’s chronological age and the predicted age, the brain age gap (BAG). This article shows how the clinical and research use of brain age prediction tacitly pathologizes the states that it is sensitive to. It will be argued that the tacit character of this transformation conceals the need for its explicit justification.