‘Mental time travel’ problems create apathy in schizophrenia
medwireNews: Patients with schizophrenia have difficulty imagining pleasant future events, which may contribute to the apathy often associated with the condition, research suggests.
"These results provide additional evidence of mental time travel impairments in schizophrenia that generalize to emotional events," say lead study author Stéphane Raffard (CHU Montpellier, France) and co-workers.
In general, the 25 schizophrenia patients in the study were less able to describe imagined future events than 25 mentally healthy controls. Their descriptions were less specific, and contained fewer sensory details and less contextual, self-referential, and other-referential information. The differences between patients and controls were true regardless of whether they were imagining a positive or a negative future event.
However, the type of event further influenced specificity, with patients being significantly less specific about positive events, relative to the controls, than they were about negative events.
Together, this indicates that the "ability to richly imagine new and specific experiences is impaired in schizophrenia," write the researchers in Psychiatry Research. They add that the patients did not perceive the task to be any harder than the controls did, so the task was not too difficult for them per se. The patients' performances were also unaffected by their verbal communication skills.
Instead, the team found an association between patients' performances and apathy, measured on the Lille Apathy Rating Scale (LARS). In particular, LARS scores increased in line with reduced ability to provide self-referential information relating to a positive future event.
This is in line with current thinking on motor cognition, say Raffard et al. They explain that "the ability to imagine oneself performing (i.e., pre-experiencing) a possible future action could facilitate the later reproduction of this action, by increasing one's motivation and effort to attain imagined future goals and by prompting the effective motor sequences/behaviors needed to achieve these goals."
But they caution that apathy is not only caused by defective mental time travel, and likely also involves "other psychological mechanisms known to be affected in schizophrenia, namely planning, prospective memory, self-efficacy beliefs, estimation of the response cost and emotion maintenance."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter