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Mood disorders (e.g. depression, apathy, and anxiety) are often observed in stroke patients, exhibiting a negative impact on functional recovery associated with various physical disorders and cognitive dysfunction. Consequently, post-stroke symptoms are complex and difficult to understand. In this study, we aimed to clarify the cross-sectional relationship between mood disorders and motor/cognitive functions in stroke patients. An artificial neural network architecture was devised to predict three types of mood disorders from 36 evaluation indices obtained from functional, physical, and cognitive tests on 274 patients. The relationship between mood disorders and motor/cognitive functions were comprehensively analysed by performing input dimensionality reduction for the neural network. The receiver operating characteristic curve from the prediction exhibited a moderate to high area under the curve above 0.85. Moreover, the input dimensionality reduction retrieved the evaluation indices that are more strongly related to mood disorders. The analysis results suggest a stress threshold hypothesis, in which stroke-induced lesions promote stress vulnerability and may trigger mood disorders.

The effect of the change in cerebrovascular reactivity (CVR) in each brain area on cognitive function after extracranial-intracranial bypass (EC-IC bypass) was examined. Eighteen patients who underwent EC-IC bypass for severe unilateral steno-occlusive disease were included. Single-photon emission CT (SPECT) for evaluating CVR and the visual cancellation (VC) task were performed before and after surgery. The accuracy of VC was expressed by the arithmetic mean of the age-matched correct answer rate and the accurate answer rate, and the averages of the time (time score) and accuracy (accuracy score) of the four VC subtests were used. The speed of VC tended to be slower, whereas accuracy was maintained before surgery. The EC-IC bypass improved CVR mainly in the cerebral hemisphere on the surgical side. On bivariate analysis, when CVR increased post-operatively, accuracy improved on both surgical sides, but the time score was faster on the left and slower on the right surgical side. Stepwise multiple regression analysis showed that the number of the brain regions associated with the time score was 5 and that associated with the accuracy score was 4. In the hemodynamically ischemic brain, processing speed might be adjusted so that accuracy would be maintained based on the speed-accuracy trade-off mechanism that may become engaged separately in the left and right cerebral hemispheres when performing VC. When considering the treatment for hemodynamic ischemia, the relationship between CVR change and the speed-accuracy trade-off in each brain region should be considered.

The effect of the change in cerebrovascular reactivity (CVR) in each brain area on cognitive function after extracranial-intracranial bypass was examined as a preliminary study in 20 patients with severe steno-occlusive disease. CVR studies and the visual cancellation task (VC) were performed before and after surgery. The Speed and Accuracy scores of the VC, which increased with improvement after the operation, were evaluated. CVR increased postoperatively both ipsilaterally and contralaterally to the surgery. Before surgery VC completion time was delayed, but accuracy was relatively maintained. In stepwise and least absolute shrinkage and selection operator (LASSO) regression models, two regions (right inferior frontal gyrus and right uncus) for the Speed score and one region (right superior occipital gyrus) for the Accuracy score were common brain regions associated with CVR change after surgery. The Speed and Accuracy scores of brain regions of the right cerebral hemisphere, which may be anatomically distant from the blood vessel anastomosis, were related to CVR change. Moreover, in the ischemic stage, with reduced CVR but no cerebral infarction, processing speed might decrease to maintain accuracy, and revascularization might increase the processing speed. In revascularization, the relationship between CVR change and the speed-accuracy trade-off in each brain region should be considered.