Behavioural phenotypes of intrinsic motivation in schizophrenia determined by cluster analysis of objectively quantified real-world performance

Abstract

Intrinsic motivation deficits are a prominent feature of schizophrenia that substantially impacts functional outcome. This study used cluster analysis of innate real-world behaviours captured during two open-field tasks to dimensionally examine heterogeneity in intrinsic motivation in schizophrenia patients (SZ) and healthy controls (HC). Wireless motion capture quantified participants’ behaviours aligning with distinct aspects of intrinsic motivation: exploratory behaviour and effortful activity in the absence of external incentive. Cluster analysis of task-derived measures identified behaviourally differentiable subgroups, which were compared across standard clinical measures of general amotivation, cognition, and community functioning. Among 45 SZ and 47 HC participants, three clusters with characteristically different behavioural phenotypes emerged: low exploration (20 SZ, 19 HC), low activity (15 SZ, 8 HC), and high exploration/activity (10 SZ, 20 HC). Low performance in either dimension corresponded with similar increased amotivation. Within-cluster discrepancies emerged for amotivation (SZ > HC) within the low exploration and high performance clusters, and for functioning (SZ < HC) within all clusters, increasing from high performance to low activity to low exploration. Objective multidimensional characterization thus revealed divergent behavioural expression of intrinsic motivation deficits that may be conflated by summary clinical measures of motivation and overlooked by unidimensional evaluation. Deficits in either aspect may hinder general motivation and functioning particularly in SZ. Multidimensional phenotyping may help guide personalized remediation by discriminating between intrinsic motivation impairments that require amelioration versus unimpaired tendencies that may facilitate remediation.

Evaluation of a new intrinsic and extrinsic motivation scale in youth with psychosis spectrum symptoms

“…This result is also consistent with the meta-analytic finding that more recently-developed negative symptom scales like the CAINS, which incorporate more experiential elements, reveal more robust relationships to IM than older scales that focus more on directly-observable behaviors [ 24 ]. However, individuals with psychosis may lack insight into impairments in their motivation [ 89 , 90 ], and direct observation and objective behavioral measures provide an important complement to self-reports [ 38 , 54 ].…”

“…However, some effort task studies have not found abnormalities [ 28 , 29 ], and studies examining token economies and the impact of monetary incentives on cognitive test performance have shown beneficial effects in schizophrenia consistent with significant EM [ 30 – 34 ]. IM is harder to operationalize in laboratory studies than EM [ 35 ]; however, fMRI studies of putative neural correlates of IM point to reductions in schizophrenia and psychosis risk [ 16 , 36 , 37 ], as does a recent free-choice behavioral study in schizophrenia [ 38 ].…”