Elsevier

Schizophrenia Research

Volume 220, June 2020, Pages 172-178
Schizophrenia Research

Effects of an extrinsic motivator on the evaluation of cognitive and daily living functions in patients with schizophrenia

https://doi.org/10.1016/j.schres.2020.03.036Get rights and content

Abstract

We investigated the effect of an extrinsic motivator on the MATRICS Consensus Cognitive Battery (MCCB) and UCSD Performance-Based Skills Assessment (UPSA) scores, which assess cognitive and daily living functions, in patients with schizophrenia. We enrolled 60 clinically stable patients with schizophrenia and allocated them to the motivator or control group. We conducted baseline assessments of cognitive function using the MCCB, daily living function using the UPSA, clinical symptoms, and psychosocial characteristics in both groups. In the retrial, we initially evaluated clinical symptoms. Next, we assigned an extrinsic motivator to the motivator group and again assessed cognitive function and daily living function using the MCCB and UPSA. Statistical analyses were performed using t-tests, Chi-square tests, Fisher's exact test, repeated measures analysis of variance, and logistic regression analysis. We found significant time Ɨ group interactions in processing speed, verbal learning, visual learning, and composite scores of MCCB. There were no significant interactions in UPSA scores. The meaningful change rates of social cognition and composite scores in MCCB were significantly higher in the motivator group than in the control group. After adjusting for additional variables, the extrinsic motivator had a significant effect on the meaningful MCCB composite score change. Conclusively, our findings suggest beneficial effects of extrinsic motivator on the MCCB score in patients with schizophrenia. In the future, the implementation and interpretation of the MCCB considering the motivation is necessary.

Introduction

Cognitive decline is one of the major symptoms of schizophrenia and is observed in various domains, including attention, executive function, and memory (Corigliano et al., 2014). Most patients with schizophrenia present with cognitive decline before the first episode, and then throughout the course of the disease (Basso et al., 1998). These cognitive symptoms are associated with the prognosis of schizophrenia and can persist even after improvement of other mental symptoms such as hallucinations and delusions (Rund, 1998).

Furthermore, cognitive symptoms are known to affect daily living function in patients with schizophrenia (Green et al., 2004). Decreased daily living function due to cognitive symptoms has been reported in patients with first-episode schizophrenia (Milev et al., 2005). Patients with schizophrenia face many difficulties when performing activities of daily living, such as the use of basic tools, using transportation, money management, eating, and cleaning (Patterson et al., 2001). In the rehabilitation of patients with schizophrenia, cognitive symptoms are considered to be a major predictor of work performance (Bryson and Bell, 2003). This impairment of daily living function not only impedes independent living, but can also cause socio-economic problems such as loss of occupational function (Rutman, 1994), increased management costs (Wu et al., 2005), and difficulty in rehabilitation treatment (Glynn, 2001).

Although therapeutic medications are continuously being developed, the recovery of cognitive and daily living function impairments in patients with schizophrenia remains unsatisfactory (Robinson et al., 2004); furthermore, patients with schizophrenia experience a deterioration in quality of life (Savilla et al., 2008). Therefore, the cognitive and daily living functionality in relation to schizophrenia treatment has garnered considerable interest, and many studies have assessed their evaluation methods (Green et al., 2008; Harvey et al., 2010; Nuechterlein et al., 2008).

An effective and ideal tool to test cognition and daily living function in patients with schizophrenia should comply with several criteria, including a sufficient reliability and validity, and the consistency of results across repeated assessments is especially important (Nuechterlein et al., 2008). However, behavior-based assessment tools can yield variable outcomes and largely depend on the condition of the examiner and subject. To overcome these limitations, examiners who implement such tests should be fully trained in advance and, if necessary, their reliability should be evaluated. Moreover, there is a necessity for constant control of the condition in patients with schizophrenia; however, this is often difficult in reality. Clinical symptoms such as depression and negative symptoms are known to impair cognitive and daily living functions (Berman et al., 1997; Ventura et al., 2009). Intraday variations might also exist, even with stable clinical symptoms; therefore, repeated examinations should be performed at the same time of day (Hufford et al., 2014). To minimize the effects of medication, such as anticholinergic effects, on the test results, the type and dose of medication should be controlled between the test and retest (Kim et al., 2019). Furthermore, the test schedule should be planned with consideration to the practice effect (Goldberg et al., 2007).

Moreover, the attitude of the subject being tested, i.e., their motivation or intention to conduct the test, is often overlooked; however, this is an important factor that might affect the test results. For example, in healthy subjects, it has been found that motivation can have a significant effect on cognitive function. Robinson et al. (2012) found that spatial memory and attention increased when healthy subjects were offered financial incentives. One study that assessed spatial attention found that attentional shifts were enhanced in healthy seniors when they were given incentives (Bagurdes et al., 2008). To our knowledge, there has not yet been an experimental comparison of the response of healthy subjects and patients with schizophrenia to an extrinsic motivator. According to a survey study by Gard et al. (2014), patients with schizophrenia are less responsive to external rewards than healthy subjects, and are more immersed in a disconnected-disengaged state. This could be because the motivation and reward system in patients with schizophrenia is impaired, which can often lead to difficulties in making meaningful, purpose-oriented actions or responding to external incentives (Choi and Medalia, 2010). This might involve various mechanisms, including dopamine-mediated basal ganglia system abnormalities, orbitofrontal cortex-driven impairments, aberrant effort-value computations, and altered activation of the prefrontal cortex (Strauss et al., 2014). The reduced intrinsic motivation of patients with schizophrenia compared to the general population might affect their neurocognition and psychosocial functioning (Nakagami et al., 2008). Intrinsic and extrinsic motivation have been reported to affect work outcomes in patients with schizophrenia who participate in employment programs (Reddy et al., 2016). Controlling these motivational factors prior to test administration might result in a more accurate assessment of the ā€˜realā€™ function of patients with schizophrenia, and thus improve the accuracy in treatment planning and determination of the treatment effect.

Therefore, we used the MATRICS consensus cognitive battery (MCCB) (Nuechterlein et al., 2008) and the UCSD Performance-based Skills Assessment (UPSA) (Patterson et al., 2001), which have high validity and reliability for the assessment of basic cognition and daily living functions in patients with schizophrenia, to identify the effect of an extrinsic motivator on the test results.

Section snippets

Subjects

We enrolled patients aged 18ā€“60Ā years who had been diagnosed with schizophrenia according to the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders fifth edition. All participants had been in rehabilitation since their symptoms had become stable, and had been receiving a constant dose of antipsychotics for the previous 3Ā months. To minimize the pure practice effect (between the first and second trial), we only enrolled patients who had already completed the MCCB

Demographic and clinical characteristics

We enrolled 60 participants (extrinsic motivator group: nĀ =Ā 30; control group: nĀ =Ā 30). In the motivator group, 25 patients received additional rewards for an increase in the retrial score compared to the baseline score. There were no significant between-group differences in sex, age, education level, duration of illness, or antipsychotic medication dose. There were no significant between-group differences in the AES, DAI, ISP, or SQLS scores related to psychosocial characteristics. Regarding

Discussion

We investigated whether an extrinsic motivator would affect the MCCB and UPSA scores in patients with schizophrenia. Our findings indicate that the extrinsic motivation did not induce a significant change in the UPSA score, which evaluates daily living function. However, the extrinsic motivator group showed a significant increase in the MCCB score, which indicates that motivation enhance cognitive function. Keefe et al. (2017) reported that the placebo response and practice effects of the MCCB

Disclosure statement

The authors have no financial benefit or interest to report.

Contributors

Do-Un Jung conducted the study protocol as primary principal investigator. Sung-Jin Kim wrote the first draft of the manuscript. Sung-Jin Kim and Dong-Wook Jeon designed the study, analyzed the data, drafted the manuscript, and participated the study protocol as the coinvestigator.

Young-Soo Seo, Sung-Soo Jung, Yoo-Chul Lee, and Jeong-Eun Kim conducted the study protocol as the co-investigator. Sung-Jin Kim and Jung-Joon Moon managed the literature searches and revised the manuscript critically

Role of the funding source

This work was supported by the 2017 Inje University research grant.

Declaration of competing interest

The authors declare no conflict of interest with any commercial or other associations in connection with the submitted article.

Acknowledgement

The authors thank staffs of the Sharing and Happiness Hospital and the Busan Metropolitan Mental Hospital for their assistance with the process of this study.

References (51)

  • M.R. Hufford et al.

    Circadian rhythms in cognitive functioning among patients with schizophrenia: impact on signal detection in clinical trials of potential pro-cognitive therapies

    Schizophr. Res.

    (2014)
  • R.S. Keefe et al.

    Characteristics of the MATRICS Consensus Cognitive Battery in a 29-site antipsychotic schizophrenia clinical trial

    Schizophr. Res.

    (2011)
  • J. Kim et al.

    Assessing the reliability and validity of the korean version of the revised insight scale for psychosis (KISP)

    Korean J. Schizophr. Res.

    (2004)
  • S.J. Kim et al.

    The effect of anticholinergic burden on cognitive and daily living functions in patients with schizophrenia

    Asian J. Psychiatr.

    (2019)
  • R.S. Marin et al.

    Reliability and validity of the apathy evaluation scale

    Psychiatry Res.

    (1991)
  • I.S. Markova et al.

    Assessment of insight in psychosis: a re-standardization of a new scale

    Psychiatry Res.

    (2003)
  • E. Nakagami et al.

    Intrinsic motivation, neurocognition and psychosocial functioning in schizophrenia: testing mediator and moderator effects

    Schizophr. Res.

    (2008)
  • T. Nilchaikovit et al.

    The effects of culture on illness behavior and medical care. Asian and American differences

    Gen. Hosp. Psychiatry

    (1993)
  • L.F. Reddy et al.

    Predictors of employment in schizophrenia: the importance of intrinsic and extrinsic motivation

    Schizophr. Res.

    (2016)
  • L.J. Robinson et al.

    Effects of intrinsic and extrinsic motivation on attention and memory

    Acta Psychol.

    (2012)
  • J. Ventura et al.

    Symptoms as mediators of the relationship between neurocognition and functional outcome in schizophrenia: a meta-analysis

    Schizophr. Res.

    (2009)
  • G. Bryson et al.

    Initial and final work performance in schizophrenia: cognitive and symptom predictors

    J. Nerv. Ment. Dis.

    (2003)
  • G. Fervaha et al.

    Motivational deficits and cognitive test performance in schizophrenia

    JAMA Psychiat.

    (2014)
  • D.M. Gardner et al.

    International consensus study of antipsychotic dosing

    Am. J. Psychiatry

    (2010)
  • S.M. Glynn

    The challenge of psychiatric rehabilitation in schizophrenia

    Curr. Psychiatry Rep.

    (2001)
  • Cited by (0)

    View full text