The Microsoft Kinect camera is a possible option for contactlessly capturing human gait, which could reflect the walkers' mental state. 
Microsoft Kinect
Fast Fourier Transforms (FFT) were conducted to extract features from the Kinect-captured gait data after preprocessing, and different machine learning algorithms were used to train the regression models recognizing anxiety and depression levels, and the classification models detecting the cases with specific depressive symptoms. 
Fast Fourier Transforms (FFT)