Figure 1.

Principal factors governing reward behavioural changes in the study cohort. The plot aligns reward behavioural response categories or ‘features’ aligned to principal factors for all 161 participants, based on an MCA of the reward symptom survey. Factor 1 is presented on the x-axis and factor 2 on the y-axis. The (x, y) coordinates of each reward survey response category or feature (dots) represent the factor score (in arbitrary units) of that feature for factor 1 and factor 2, respectively (see also Supplementary Table 4). The factor score quantifies the contribution of that feature to the factor. Increasing discrimination between features corresponds to increasing distance along each axis; the greater separation of features along the x-axis (note change of scale) indicates that factor 1 accounts for most of the variance in reward behavioural features in the participant cohort, discriminating presence from absence of altered reward behaviours. Altered responsiveness to sex, music, religion and colour are relatively well discriminated by factor 2 (y-axis). Reward features that aggregate tend to co-occur in the same participants or group of participants. Features that are more distant from the origin are less frequently reported and signify deviation from average cohort behaviour. Diagnostic group features are visualized in this plot as supplementary variables (triangles); their coordinates were derived by projecting them onto principal factors 1 and 2. The positioning of the bvFTD and HC diagnostic groups at opposite ends of the x-axis relates to their strong association with factor 1 (i.e. discriminating presence from absence of altered reward behaviours); the positioning of the svPPA and lvPPA groups at opposite ends of the y-axis relates to their strong association with factor 2 (i.e. discriminating the direction of altered reward behaviours). AD, patient group with typical Alzheimer’s disease; Appetite ±, appetite increased/decreased; Art ±, art responsiveness increased/decreased; bvFTD, patient group with behavioural variant frontotemporal dementia; Colour +, increased responsiveness to colours; HC: healthy control group; lvPPA, patient group with logopenic variant primary progressive aphasia; Music ±, music responsiveness increased/decreased; NC, no change; nfvPPA, patient group with non-fluent/agrammatic variant primary progressive aphasia; Religious +, increased religiosity; Sex ±, libido increased/decreased; svPPA, semantic variant primary progressive aphasia; Sweet +, increased sweet tooth.