Area of Neuroscience, SISSA, Trieste, 34136, Italy.
Zayed University, Dubai, 19282, United Arab Emirates.
Sci Rep. 2019 Feb 15;9(1):2151. doi: 10.1038/s41598-018-38284-x.
The value people attribute to rewards is influenced both by the time and the effort required to obtain them. Impairments in these computations are described in patients with schizophrenia and appear associated with negative symptom severity. This study investigated whether deficits in temporal and effort cost computations can be observed in individuals with subclinical psychotic symptoms (PS) to determine if this dysfunction is already present in a potentially pre-psychotic period. Sixty participants, divided into three groups based on the severity of PS (high, medium and low), performed two temporal discounting tasks with food and money and a concurrent schedule task, in which the effort to obtain food increased over time. We observed that in high PS participants the discounting rate appeared linear and flatter than that exhibited by participants with medium and low PS, especially with food. In the concurrent task, compared to those with low PS, participants with high PS exerted tendentially less effort to obtain snacks only when the required effort was high. Participants exerting less effort in the higher effort condition were those with higher negative symptoms. These results suggest that aberrant temporal and effort cost computations might be present in individuals with subclinical PS and therefore could represent a vulnerability marker for psychosis.
人们对奖励的重视程度受到获得奖励所需的时间和努力的影响。在精神分裂症患者中，这些计算能力受损的情况已经得到描述，且似乎与阴性症状的严重程度有关。本研究旨在调查是否可以观察到具有亚临床精神病症状（PS）的个体中存在时间和努力成本计算的缺陷，以确定这种功能障碍是否已经存在于潜在的精神病前期。60 名参与者根据 PS 的严重程度（高、中、低）分为三组，进行了两项与食物和金钱相关的时间折扣任务以及一项并发时间表任务，其中随着时间的推移，获得食物所需的努力会增加。我们发现，在高 PS 参与者中，折扣率似乎呈线性且比中 PS 和低 PS 参与者更为平坦，尤其是在食物方面。在并发任务中，与低 PS 参与者相比，高 PS 参与者在所需努力较高时，往往较少努力获得零食。在较高努力条件下付出较少努力的参与者具有更高的阴性症状。这些结果表明，亚临床 PS 个体可能存在异常的时间和努力成本计算，因此可能代表精神病的易感性标志物。
