Abstract
Objective: To get better insights into emotion processing in patients with MSA-P compared to healthy controls (HCs) by using two different Eye-Tracking paradigms.
Background: MSA is a rare and fatal neurodegenerative disease. Hallmarks of the disease include rapid progression of parkinsonian or cerebellar symptoms combined with autonomic failure. The lack of emotion recognition in IPD has been previously described, however the knowledge in MSA patients is lacking.
Method: In this prospective, single-centre study, we included 14 patients with MSA-P and 15 age and sex matched HCs. Every participant was evaluated by using the UMSARS and MoCA score, answered the HADS-D and the Toronto Alexithymia Scale (TAS-20). Emotion recognition tasks and were carried out on an eye tracking device (Tobii TX 300). The modified Geneva Emotion Recognition Test showed 24 short videos of people expressing different emotions. In the second test, 63 static faces of three emotions (joy, anger, fear) partially morphed with a neutral expression were presented in 3 stages of intensity. We analysed fixations on predefined areas of interest (AOI; whole body, whole face, eye region, mouth and nose). Furthermore, the parameters total fixation duration (TFD) fixation count (FC) and time to first fixation (TTFF) were calculated for every AOI.
Results: MSA-P patients scored higher on HADS scale compared to HCs (P < 0.001). Both groups performed similar with 50.1% correct answers in the MSA-P group vs. 54.6% in the control group. We observed a significant difference for FC parameters in the face and body region (both P < 0.001). There were no other differences (all P values > 0.1). Bivariate correlation showed a significant correlation between HADS scores and FC body (P = 0.008) and FC face (P = 0.009) values.
At the static emotion test, TTFF face was significantly shorter in MSA-P (P = 0.021) and contrarily longer at TTFF eyes (P = 0.019). FC face scored higher and FC eyes lower (P < 0.001) in MSA-P. Furthermore, TFD of the eyes was shorter (P = 0.016) in MSA-P and longer at the nose region (P < 0.001).
Conclusion: Although MSA-P patients recognized emotions as well as HCs, there are differences regarding the gaze behaviour. MSA-P patients tend to avoid direct eye contact with lower FCs and a shorter TFD in the eye region compared to HCs. However, we cannot rule out the influence of higher depression scores in the MSA-P group that may have also influenced the gaze behaviour.