Our knowledge of the organisation of the human brain at the population-level
is yet to translate into power to predict functional differences at the
individual-level, limiting clinical applications, and casting doubt on the
generalisability of inferred mechanisms. It remains unknown whether the
difficulty arises from the absence of individuating biological patterns within
the brain, or from limited power to access them with the models and compute at
our disposal. Here we comprehensively investigate the resolvability of such
patterns with data and compute at unprecedented scale. Across 23810 unique
participants from UK Biobank, we systematically evaluate the predictability of
25 individual biological characteristics, from all available combinations of
structural and functional neuroimaging data. Over 4526 GPU*hours of
computation, we train, optimize, and evaluate out-of-sample 700 individual
predictive models, including multilayer perceptrons of demographic,
psychological, serological, chronic morbidity, and functional connectivity
characteristics, and both uni- and multi-modal 3D convolutional neural network
models of macro- and micro-structural brain imaging. We find a marked
discrepancy between the high predictability of sex (balanced accuracy 99.7%),
age (mean absolute error 2.048 years, R2 0.859), and weight (mean absolute
error 2.609Kg, R2 0.625), for which we set new state-of-the-art performance,
and the surprisingly low predictability of other characteristics. Neither
structural nor functional imaging predicted individual psychology better than
the coincidence of common chronic morbidity (p<0.05). Serology predicted common
morbidity (p<0.05) and was best predicted by it (p<0.001), followed by
structural neuroimaging (p<0.05). Our findings suggest either more informative
imaging or more powerful models will be needed to decipher individual level
characteristics from the brain.

人脑组织、功能差异、可解决性、预测模型、个体特征解析需要更具信息量的成像或更强大的模型。