ANTICIPATING PLEASURE AND EFFORT IN SCHIZOPHRENIA 1
Do People With Schizophrenia Have Difficulty Anticipating Pleasure, Engaging in Effortful Behavior, or Both?
David E. Gard, Amy H. Sanchez, Kathryn Cooper, Melissa Fisher, Coleman Garrett, and Sophia Vinogradov
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Citation
Gard, D. E., Sanchez, A. H., Cooper, K., Fisher, M., Garrett, C., & Vinogradov, S. (2014, August 18). Do People With Schizophrenia Have Difficulty Anticipating Pleasure, Engaging in Effortful Behavior, or Both?. Journal of Abnormal Psychology. Advance online publication. http://dx.doi.org/10.1037/abn0000005
Introduction
The main purpose of this study was to investigate the effects of “motivational impairment” on the goal directed behavior of individuals diagnosed with schizophrenia. This was accomplished by measuring the levels of pleasure (reward) and effortfulness in the activities and future goals of the subjects. These two factors were selected to be measured due to the fact that they are two of the component processes of motivation which has been proven by previous research to be affected by schizophrenia.
Research has found inconsistencies in the assessment of pleasure and reward in schizophrenia patients. For instance, while Anhedonia has been frequently reported to be associated with schizophrenia (Herbener & Harrow, 2002; see Gard et al., 2014), patients do not report a decrease in pleasure or positive stimuli (Cohen & Minor, 2010; see Gard et al., 2014). These inconsistencies have been explained to be the result of clear-cut distinctions between the different temporal components associated with specific types of reward and pleasure. Schultz (2002) and Wise (2002) (as cited in Gard et al., 2014) have shown that there is a physiological difference in how anticipatory pleasure and consummatory (in-the moment) pleasure are processed in the brain. While consummatory pleasure involves serotonergic and opioid systems, anticipatory pleasure involves dopaminergic and mesolimbic projections (Schultz, 2002; Wise, 2002; see Gard et al., 2014). In another study conducted using an Ecological Momentary Assessment (EMA), participants with schizophrenia showed similar levels of consummatory pleasure, but depleted levels of anticipatory pleasure (Gard et al., 2007; see Gard et al., 2014). Consequently, pleasure was selected to be a dependent variable (DV) in this study.
Individuals diagnosed with schizophrenia have reported difficulty in anticipating rewards (Buck & Lysar, 2013; Gard et al., 2007; see Gard et al., 2014) as well as in processing rewards (Strauss, Waltz & Gold 2008; see Gard et al., 2014). The link between reward and motivation has been established through the study conducted by Juckel et al. (2006) (as cited in Gard et al., 2014) which showed decreased ventral striatal activation during reward processing from individuals diagnosed with schizophrenia; decreased ventral striatal activation has been associated with anhedonia (Juckel et al., 2006; see Gard et al., 2014). This also relates reward to anticipatory pleasure.
Research has indicated that patients with high negative symptoms of schizophrenia have difficulty assessing the effort required to accomplish a task which would provide a high reward (Gold et al., 2013; see Gard et al., 2014). Furthermore, in addition to difficulties assessing the effort involved, patients also appeared to have difficulty putting in the effort required to do a particular task. In relation to reward, Fervaha, Graff-Guerrero, et al. (2013) (as cited in Gard et al., 2014) showed that patients of schizophrenia only had problems when it came to the assessment of the effort involved to achieve a reward, and not when ascertaining the value of a reward. (Fervaha, Graff-Guerrero, et al. 2013; see Gard et al., 2014)
In light of the aforementioned findings in past literature, the researchers came up with three assumptions, and the resulting research questions reflected them. The assumptions were that individuals diagnosed with schizophrenia would have:
A deficit in anticipatory pleasure
Difficulty in anticipating and processing rewards
Difficulty assessing and expending the necessary effort required to accomplish a task
Using these assumptions, the researchers of the present study came up with 5 research questions. The following has been taken from Gard et al. (2014)
Compared with a socio-demographically matched group of healthy participants, do participants with schizophrenia demonstrate fewer daily activities and goals, decreased anticipatory pleasure for their upcoming goals, decreased pleasure-based goals, but intact in-the-moment pleasure? (Hypothesis)
Do participants with schizophrenia pursue goals and activities that are less effortful than healthy comparison participants, and do they have difficulty assessing the effort of an upcoming goal? (Hypothesis)
Do people with schizophrenia have difficulty completing their goals, and is this related to anticipation or experience of pleasure, or to how effortful the goal is? (Hypothesis)
In people with schizophrenia, what is the relationship of anticipatory pleasure and effort exertion or assessment to: cognitive dysfunction, symptoms, and functioning? (Alternative Hypothesis)
To what degree could group differences found in Questions 1– 4 be explained by any other non-diagnostic group differences? (Alternative Hypothesis)
Participants
The selection of participants differed between the experimental and control group. The subjects for the control group were selected through postings on the Internet and the distribution of flyers in the San Francisco Bay Area. Initially, forty-three individuals agreed to participate and signed the informed consent forms. However two of them dropped out; one, finding the study to be too much of a burden, dropped out on the first day, and the other failed to respond to even a third of the phone calls. The subjects for the experimental group were selected from outpatient clinics and day treatment centers in the Bay Area. Fifty patients of schizophrenia initially signed the informed consent forms but three decided to drop out; two dropped out even before the experiment started citing that it was too intrusive, and the other dropped out after two calls on the first day. All in all, the results of the study were formulated based on the results from forty-one subjects without schizophrenia and forty-seven subjects with either schizophrenia (n=31) and schizoaffective disorder (n=16). Diagnoses for the conditions were confirmed for all participants using the DSM-IV-TR.
Strict exclusion criteria for the whole sample, and especially for the patient group, were established and implemented. Individuals who had had traumatic head injuries which leads to bouts of unconsciousness, had substance abuse problems in the last six months, mental disorders, or illiterate in English were all excluded. Patients who had been hospitalized in the last three months or had had their medication or dosage changed in the last month were also excluded from the study. Both groups were predominantly white males and had relatively no demographic differences between groups except for the symptoms for the disorder and employment rates. Only 17 percent of the individuals in the patient groups were employed full time or part time (4% and 13% respectively), compared to the 68 percent of full time and part time employees (24% and 44% respectively) in the control group. The experimenters did account for this discrepancy during the results phase.
Method
Four different types of assessments were used during this study, although the EMA remained the primary form of assessment of pleasure and effort. The Ecological Momentary Assessment is generally used in situations where specific activities and goals of the participants in a study need to be explicated. This study utilized a modified version of the EMA where cell phone calls were used instead of the traditional self-report forms, which were filled at particular intervals of time; cell phones were provided to every participant irrespective of who does or doesn’t own a cell phone. Trained research assistants called each participant four times every day, between 0900hrs and 2100hrs, for seven days to conduct a “semi-structured” interview. A majority of the questions were open ended and participants were encouraged to give detailed descriptions of their daily activities and goals. Some questions asked them how much pleasure/effort was associated with a particular task; their responses were rated on a Likert Scale (0 = not at all; 5 = extremely). The answers were categorized based on the research questions. Four independent raters then scored the pleasurability, effortfulness, difficulty, and etc… of all the goals and activities reported by the participants on a 0-3 Likert Scale. A subset of participants with no demographic differences from the original sample was also tested to determine the difficulty of the tasks they attempted; also measured on a 0-5 Likert Scale.
After the completion of the week of EMA, two independent research assistants travelled to the homes of the participants in order to determine the levels of stimulation and reward provided by the environment. Several subjects from the patient and control group (seven and nine respectively) decided to opt out from this stage of assessment citing different reasons. The levels of stimulation and reward were measured in terms of three elements; aesthetics of the home, availability of media, and social stimulation. These were measured using a combination of a modified version of the Environmental Assessment Scale (EASy) and the Home Observation for the Measurement of the Environment (HOME). Scores from each of the three elements as well as individual scores were averaged; the results had high inter-rater reliability.
Two additional assessments were conducted on the patient group; they were tested for neurocognition, and were also clinically rated for functioning. During the former, 40 subjects with no demographic differences completed a Measurement and Treatment Research to Improve Cognition in Schizophrenia (METRICS) Consensus Cognitive Battery. An overall average of their results was used for all the future analyses. During the latter, a Quality of Life Scale (QLS) was used to assess overall functioning of patients with respect to elements such as “social initiative” and “capacity for empathy”; “motivation” and “anhedonia” were not measured since they were already been used as DVs for the EMA.
Procedure
Rigorous pilot testing was carried before the actual experiment was conducted. Factors such as whether participants understand what the terms “activity” and “goals” meant in the context of the present study were determined during the piloting phase. After participants were selected, orientations on how to properly respond to an EMA during laboratory testing were conducted; they were subsequently required to provide written informed consent before going any further. Most of the basic questions that research assistants asked during the study were previously determined with respect to their effectiveness.
Before they were provided a larger sample of the study to be rated, the coders were extensively trained for their task using a smaller subset of the original sample. When the results from the EMA were presented to the four independent raters, the responses from the experimental and control group were presented together in a randomized fashion. Attributes that were to be rated by the coders (such as pleasurable activities and effortful activities) were clearly defined within parameters.
As previously mentioned, cell phones were provided to each participant to be used purely for the purposes of the study, and to be returned after its conclusion. The EMA and subsequent home assessments were recorded on audio for post hoc quality assessment. Monetary compensations were provided to every participant upon the completion of the whole study (marked by the returning of the cell phones) and for the completion of the several different assessments conducted during it; the amounts were different for each assessment.
Data Analysis
The independent variables (IVs) for all stages of assessment were individuals with schizophrenia and individuals without schizophrenia. The dependent variables (DVs), however, weren’t as consistent throughout the experiments, except for pleasure and effort. A number of other variables such as reward, difficulty, and sociability were also measured during the different stages of the study. The basic design of every experiment conducted in the study was to determine how the experimental group was different from the control group with respect to the numerous DVs they were being tested on.
Two types of analyses were used to determine the statistical significance of the results obtained. The theoretical principles of these analyses are too convoluted to be properly explained, but for all intents and purposes, they seem to have been implemented correctly. Hierarchical Linear Modeling (HLM) was used in EMA analyses. Its effectiveness comes from the fact that it can categorize data into separate levels so that analysis of data from one level wouldn’t influence others. The EMA data were separated into Level one data (the multiple observations of participants) and level two data (between group differences in terms of neurocognition and functioning). For each research question and assessment, separate analyses of variation (ANOVA) were computed and their significance determined. Significance levels obtained through the HLM were presented as “pseudo-r2”.
Independent sample t tests were conducted on the results obtained during the home assessments. It was used to determine whether or not the average level of stimulation that was computed for the control and experimental group was significant, with respect to each of the three aforementioned elements they were being measured on. Furthermore, the significance for the results of all five of the research questions seems to involve computation of t tests. The p values for them varied from 0.5, 0.1, and 0.001.
Limitations and Future Research
Dr. Marvin Monroe,
Department of Psychology,
Springfield University
Sir,
As requested, I have reviewed the study about pleasure and effort in schizophrenia, and it has got a number of interesting findings. Analysis of the results revealed that subjects with schizophrenia indeed set less effortful goals and engaged in less effortful activities. They also found that patients had difficulty determining with accuracy how difficult or effortful a task was going to be (in terms of resultant rewards). However, unlike the two aforementioned findings which were within the researchers’ expected results, the final finding was not; it showed that patients with schizophrenia engaged in more pleasurable activities, and that they set goals that were, and also anticipated by them, to be more pleasurable.
I also analyzed the study for potential limitations and further research areas. In terms of limitations, it had many. Employment differences between the two sample groups felt like a deal breaker; however, the researchers did not find any significant difference when they computed the study for employment differences. The researchers themselves pointed out many, if not most, of the limitations that I found in this study. They highlighted four of them in the discussions and gave possible reasons for their occurrence. The foremost limitation according to the researchers was the reason behind the unexpected result which disproved their hypothesis. According to them, the social interactions with the research assistants might have induced pleasurable feelings within some participants. Other limitations include them focusing solely on short-term goals, the relatively new use of home assessment as a tool for measuring motivation in schizophrenia patients (which they also pointed out as a future research area), and the fact that some assessments used fewer number of participants than the actual sample group.
The researchers reported that there are no data available on “the relationship between effort assessment and functioning” and the “assessment of effort in daily life in Schizophrenia”. Another key area of research could be why social interactions increased anticipatory pleasure in patients with schizophrenia.
This study illustrates several different ways in which schizophrenia patients could increase their motivation about everyday activities and goals. It was a very fascinating read. Thank you for giving me the opportunity to review such a study.
Sincerely,
Ibrahim Fatheen Abdul Sameeu
