A novel method for objective quantification of apathy based on gaze and physiological reactivity to stimuli presented in a virtual reality environment

Abstract INTRODUCTION We developed a tool for objective quantification of apathy. METHODS Participants ( n = 97; 67 with cognitive impairment, 30 cognitively normal; mean age = 74.3 ± 6.2 years, 56.7% females) were exposed to emotional and cognitive stimuli in a virtual reality environment. Gaze metrics (time to first fixation [TTFF] and total fixation duration [TFD]) and autonomic nervous system (ANS) reactivity were measured. Apathy and depression were clinically assessed using the Lille Apathy Rating Scale short version and the Geriatric Depression Scale 15‐item version, respectively. Cutoffs of ≥ –7 and ≥ 5 were used to define apathy and depression, respectively. RESULTS The sample comprised 14 participants with apathy only, 9 with depression only, 10 with both, 63 with neither, and 1 with missing data. For all emotional stimuli, participants with apathy only showed longer TTFF ( P = 0.039, effect sizes [ES] = 0.798), and shorter TFD ( P = 0.023, ES = 0.578) compared to those without apathy or depression. ANS reactivity was not associated with apathy. DISCUSSION Apathy is associated with decreased gaze engagement at emotional stimuli. Highlights Apathy measurement via questionnaires is limited by subjectivity biases. Apathy measurement via questionnaires is limited by simplistic scoring. We present a novel method for objective measurement of apathy. Gaze characteristics reflect the emotional and cognitive components of apathy.