Motivation and emotion/Book/2015/Schizophrenia and motivation

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Schizophrenia and motivation:
What is the effect of schizophrenia on motivation and what can be done about it?

Overview[edit | edit source]

Figure 1. Original Symptoms of Schizophrenia.

Schizophrenia is a disabling mental disorder that involves sets of symptoms (see Figure 1 for original symptoms) which severely impacts the lives of individuals diagnosed, [grammar?] one domain of impact is motivation. Lack of motivation can have detrimental counter effects on general well-being (Barch, Teadway & Schoen 2014), physical health (Klingaman, Viverito, Medoff, Hoffmann & Goldberg, 2014) and further adverse effects on mental health (Sands & Harrow, 1999). Motivational deficits impact ability to engage in and experience positive outcomes in educational, occupational and social domains (Barch et al., 2014).

Factors related to these motivational deficits include negative symptoms of schizophrenia, co-morbid depression and side effects of medication. Negative symptoms of schizophrenia involve a lack of motivation to engage in social interaction and goal directed behaviour (Hartmann, Kluge, Kalis, Moizisch, Tobler & Kaiser, 2015). Additionally, [missing something?] majority of individuals diagnosed with schizophrenia suffer from depression at some stage or throughout the course of their primary illness (Sands & Harrow, 1999). Depression has been associated with high avoidance motivation/low goal directed motivation (Dickson, Moberly, & Kinderman, 2011). Additionally, negative side effects of medication can create problems with goal directed behaviour (Klingaman et al., 2014).

Motivational deficits can be harmful, {{grammar}] schizophrenic individuals have up to three times the mortality rates compared with the general population (Klingaman et al., 2014). Lack of motivation can lead to unhealthy diet and inactive lifestyle. This, in turn, leads to diseases associated with obesity such as cardiovascular disease and diabetes (Klingaman et al., 2014).

Identifying mechanisms behind motivational deficits for individuals with schizophrenia could greatly improve their social, occupational and educational lives (Barch et al., 2014).

This chapter addresses the following questions:

  1. How do symptoms of schizophrenia effect motivation?
  2. How does co-morbid depression effect motivation?
  3. How do negative side effects of medication impact motivation?
  4. What can be done to increase the motivation in individuals diagnosed with schizophrenia?

Schizophrenia[edit | edit source]

[Provide more detail]

Symptoms[edit | edit source]

Table 1.
Symptom Domains of Schizophrenia


Three Symptom Domains:

1. Positive symptoms: delusions and hallucinations

2. Negative symptoms: blunted affect, alogia, anhedonia, avolition and asociability

3. Cognitive symptoms: impaired attention, memory and executive functioning .

Schizophrenia is a chronic mental disorder that involves several sets of symptoms (see Table 1). The Diagnostic and Statistical Manual of Mental Disorders (4th edition) outlines 5 central symptoms required for diagnosis. These include; delusions, hallucinations, disorganised speech, grossly disorganised or catatonic behaviour and negative symptoms. Further symptoms of schizophrenia involve cognitive and attentional deficits (American Psychiatric Association, 1994). Onset is typically between late teens and mid 30s, with the most common ages in men being 18 to 25 years and 25 to mid 30s in women. Onset prior to adolescence and over 40s is rare however, some cases have been reported with onset at age 5 to 6 and above 60 (American Psychiatric Association, 1994).

Causes[edit | edit source]

There are numerous contributing factors towards development of schizophrenia. These include genetics, prenatal development, environmental factors and substance abuse (Bassett, Chow, O’Neill, & Brzustowicz, 2001). Currently, research relies on the neurodevelopmental model and suggests that genetic factors are the primary cause of schizophrenia (Insel, 2010). The neurodevelopmental perspective suggests that abnormalities in the development of the brain occur years before onset of illness. What is known as onset could possibly be late stages of the illness (Insel, 2010).

Treatment[edit | edit source]

Anti-psychotic medications are the primary treatment used to manage symptoms of schizophrenia although, these medications are best taken along with psychological and psycho-social treatments (van Os, & Kapur, 2009). Anti-psychotic medications are predominately used to manage psychotic or positive symptoms such as delusions, hallucinations and disorganised thoughts. However, these medications also treat cognitive impairment and anxiety symptoms in patients (Muench, & Hamer, 2010). Newer, atypical anti-psychotics have been found as equally effective and exhibit less side effects than older, typical anti-psychotics. Some atypical anti-psychotics include Clozapine and Risperidone which are widely used. Although negative side effects of atypical anti-psychotics do occur, weight gain and insulin resistance for example have been associated with these newer drugs (Muench, & Hamer, 2010)[grammar?].

Psychological treatments such as Cognitive Behavioural Therapy (CBT) and community-case management are additional treatment options often used in conjunction with anti-psychotics (van Os, & Kapur, 2009). The combination of medications along with psychological and psycho-social support has been found extremely effective in managing the symptoms of schizophrenia (van Os, & Kapur, 2009).

Motivation[edit | edit source]

Motivation has widely been defined as an internal state, need or desire that functions to direct and maintain behaviours which are goal orientated (Nakagami, Hoe, & Brekke, 2008). To be motivated to do something means to be motivated to move, to be energised towards obtaining some form of goal or to reach an end point (Ryan, & Deci, 2000). Many theories of motivation have now been developed.  

Self-determination theory[edit | edit source]

Figure 2. Motivation table based on Ryan and Deci Self-Determination Theory (2000).

The Self-Determination Theory (SDT) proposes two main types of motivation; intrinsic and extrinsic motivation (Ryan & Deci, 2000). Intrinsic motivations are suggested to arise from a psychological need for competence, autonomy and relatedness. Extrinsic motivations on the other hand arise from external influences such as punishment or reward. A third state exists called Amotivation, this is a state of complete lack of or absence of motivation (Ryan & Deci, 2000) (see Figure 2).

Application of self-determination theory[edit | edit source]

SDT has been applied to the study of motivation deficits in schizophrenia (Gard, Sanchez, Starr, Cooper, Fisher, Rowlands & Vinogradov, 2014). One study using Ecological Momentary Assessment (EMA) found that participants with schizophrenia were less motivated by autonomy and competency needs compared with healthy controls. Controls and schizophrenic participants were equally motivated by relatedness and punishment. Further to this, higher levels of disconnected/disengaged goals were associated with more severe negative symptoms and poorer functioning in schizophrenic patients (Gard et al., 2014). Researches highlight that lack of goals motivated by autonomy and competence may arise from previous failure in achievement (lack of autonomy) and environments that were non-supportive of skill development (lack of competence) (Gard et al., 2014). However, this study was examining goals not activity and may not reflect actual daily activities carried out by these individuals.

Expectancy-value theory[edit | edit source]

The Expectancy-Value theory of motivation is based on an early Social Learning Theory which suggested a major source of self-motivation is the process of goal setting and self-evaluation reactions to own behaviour (Bandura, & Schunk, 1981). The Expectancy-Value theory expanded on this by suggesting expectations of success on tasks that are learning orientated, along with perceived task value are determinants of motivation to learn (Eccles, & Wigfield, 2002). Choice to engage in and to continue learning tasks is influenced by perceptions of self-competency and task difficulty as well as the relative value of the task to the individual (Eccles, & Wigfield, 2002).

Application of expectancy-value theory[edit | edit source]

It has been suggested that withdrawal from task orientated and effortful activities may function as a defence against expected failure and negative self-evaluation in individuals with schizophrenia (Choi, Fiszdon & Medalia, 2010). One study examined the effect of self-competency and perceived task value on task persistence via a computer arithmetic assessment. Self-competency was significantly related to perceived task value and higher expectations for task success were associated with higher levels of persistence in learning tasks. These findings support the idea that high task value and perceived success/self-competence assist with motivation to learn (Choi et al., 2010).

Schizophrenia and motivational deficits[edit | edit source]

How do symptoms of schizophrenia effect motivation?[edit | edit source]

Negative symptoms

Negative symptoms of schizophrenia include avolition, apathy, asociality and anhedonia (Hartmann et al., 2015). These symptoms all involve motivational deficits. A lack of motivation to get started and continue activities that are self-directed (avolition), a lack of interest and enthusiasm (apathy) and a lack of motivation to engage in social interaction (asociality). Anhedonia however, refers to another occurrence that impedes a person’s motivation; an inability to feel pleasure (Hartmann et al., 2015). These motivational deficits can have negative effects on ability for action to initiate and continue tasks (Hartmann et al., 2015). This absence of "doing things" can severely impact mental and physical health.

Low effort expenditure

Individuals with schizophrenia are more likely to opt for lower level effort tasks compared with harder task that may end with more beneficial outcomes. This can impact daily living and quality of life for these individuals (Gard et al., 2014). One study utilised an Ecological Momentary Assessment (EMA) using mobile phones to assess the daily activities and goals of participants with and without schizophrenia. Participants with schizophrenia differed from healthy controls, they chose activities that were less effortful and experienced fewer, long term positive outcomes (Gard et al., 2014). An additional study examined motivation in a problem solving and open type scenario via computer task (Hartmann et al., 2015). One group could stop when they felt enough options had been generated to initiate goal directed action, the other group were encouraged not to stop until the maximum number of options were chosen. Schizophrenic participants generated fewer goal directed options compared with non-schizophrenic participants and option generation held the strongest links to apathy compared with other symptoms (Hartmann et al., 2015). However, this task was completed on a computer and may not reflect real life activities. This commonality of choosing low low effort tasks can be detrimental in the engagement and continuation of goal directed behaviours for schizophrenic individuals.

Pleasure experience

Examining experiences of pleasure in individuals with schizophrenia is important in untangling the low level motivation phenomenon that occurs with this illness. Two types of pleasure experiences have been defined; consummatory (in-the-moment pleasure) and anticipatory (anticipation of future pleasure) (Gard, Kring, Horan & Green, 2007). Researchers have found that schizophrenic participants experience similar consummatory pleasure however, report less anticipatory pleasure. Further to this, levels of anhedonia have been related to anticipatory pleasure but not to consummatory pleasure (Gard et al., 2007). Interestingly, a further study conducted by Gard and colleagues (2014) found contradictory findings of anticipatory pleasure (Gard et al ., 2014). Schizophrenic patients in this study reported higher levels of anticipated pleasure compared with non-schizophrenic participants. However, this contradictory finding could be due to methodological differences, each study utilised differing methods of contact which were phone calls (Gard et al ., 2014) and face to face interview (Gard et al.,2007). Whether motivation is reduced due to lack of pleasure experience for current activities, or, anticipation of future activities is still unclear however, there are associations between anhedonia and low motivation. (Gard et al., 2007).

How does co-morbid depression effect motivation?[edit | edit source]

It has been well established that individuals diagnosed with schizophrenia and co-morbid depression suffer from motivational deficits (Sands & Harrow, 1999). Depression has been found in schizophrenic patients during first admission, acute hospital stays, post hospital stays and during relapse. Increased relapse and reduced functioning in schizophrenic patients has also been linked to depression (Sands & Harrow, 1999). Depression severely impacts motivation, with depressed individuals being less likely to choose approach motivated tasks even when presented a reward (Davidson & Henriques, 2011). Additional research has shown no difference in depressed and non-depressed individuals in terms of approach motivation however, found differences in outlook (Dickson, Moberly, & Kinderman, 2000). Specifically, depressed individuals judged goal approach tasks as less likely to end in positive outcomes and expressed feeling as they had less control over outcomes (Dickson et al., 2000). These findings suggest that depression effects motivation, weather via poor outlook on outcomes (Dickson et al., 2000) or by facilitating avoidance motivation as opposed to approach motivation (Davidson, & Henriques, 2011).

How do negative side effects of medication impact motivation?[edit | edit source]

Identifying specific side effects of anti-psychotics is difficult as consumers may be taking additional medications and symptoms of schizophrenia may be confused with medication side effects (McCann, Clark, & Lu, 2008). However, numerous negative side effects have been reported. Typical anti-psychotics are associated with side effects such as tremors, involuntary muscle spasms, sexual dysfunctions and sedation (McCann et al., 2008). Newer atypical medications have been linked to weight gain and dyslipidemia (high levels of fat or cholesterol in the blood) (McCann et al., 2008). Neuroleptic dysphoria is an additional side effect of anti-psychotic medications. A term used to describe a set of negative symptoms that involve problems with motor function, mood, arousal and motivation (Voruganti, & Awad, 2004). This state involves feelings of dejection and dissatisfaction and has been linked with high levels of suicide and violent behaviours (Voruganti, & Awad, 2004). Low mood and arousal, weight gain and sedation can impact motivation greatly. When low energy levels occur, individuals tend to opt out of goal directed behaviour. Lessening negative side effects of anti-psychotics would not only improve motivation and energy levels, but enhance general health and well-being for individuals effected (McCann et al., 2008).

Seeing it in their eyes[edit | edit source]

A qualitative interview style study examined the subjective experiences of individuals with schizophrenia. Participants were asked to describe how they experienced motivation in their lives. Most patients spoke about effects of medication, secondary effects of depression and social stigmas such as laziness (Boydell, Gladstone & Volpe, 2003) (see Figure 3).

Participants reported the following:

Stigma
“There’s the attitude that if you’re unmotivated it means you have attitude problems, you’re lazy, a layabout. If somebody sees us in the street but doesn’t know we’re ill… they think your lazy, so if you’re unmotivated they think you’re lazy. So there’s a stigma there.” (Boydoll et al., 2003).

Depression

“I thought that I would never get back to normal and I started sinking into a depression. I went into a very deep, serious depression that all I wanted to do was sleep. I didn’t want to see the world no more. I started sinking into a deeper depression… it got to the point where I didn’t want to watch TV, eat, like it got that bad…” (Boydoll et al., 2003).

Medication

“I was just living in my sleep ... the medications made me very drowsy. With the medications, you’re so flattened, just kocked flat and often you can’t read, I couldn’t even sit through the movies… I was so burned out from the illness, from all the meds that I couldn’t do what I used to do, what Id taken for granted… I was on such brutal medication it was really impossible for me to do anything. I was just burned out from being nuts.” (Boydoll et al., 2003).

This study highlights the need to not only focus on negative symptoms of schizophrenia and side effects of medication but further, factors such as social stigma, environmental influences and influences of significant others in understanding the motivational issues people living with schizophrenia experience (Boydoll et al., 2013).

What Can Be Done About It?[edit | edit source]

Low effort expenditure and pleasure experience[edit | edit source]

To address problems related to avolition, apathy and anhedonia, treatment providers in a community setting could assist schizophrenic participants with low-effort, pleasurable goals. This could be done by breaking down goals into smaller, lower effort steps (Gard et al., 2014). Individuals could begin to associate activities and goal orientated behaviour with pleasurable rewards to enhance motivation (Gard et al., 2014). It is also important to instill self-competent beliefs in these individuals to assist confidence to engage in tasks, this could be done by providing support during goal attainment and reinforcement of goal attainment/self-competent beliefs once goals have been reached (Choi et al., 2010). Focusing on treatments that emphasise and encourage competence and avoid criticism could improve willingness to engage in tasks for these individuals (Gard, 2014).

Practical solution[edit | edit source]

It has been suggested that volunteering (engaging in unpaid work) is beneficial for people living with schizophrenia. However, one study examining the effects of pay on maintaining participation in work activity found that paid individuals were more willing to begin work compared with the no-pay condition (Bell, Milstein & Lysaker, 1993). Furthermore, over 90% of non-pay group dropped out of the program by the 6th week and individuals in the pay condition worked seven times the hours worked by the non-pay group. Further to this, participants in the pay group showed an improvement in depressive symptoms, with a decrease in symptoms over the 26 week program (Bell et al., 1993). These results suggest that pay is a positive incentive to motivate individuals living with schizophrenia to work, and that working can have a positive impact on health and well-being (Bell et al., 1993). Unfortunately, there is little paid work outside of these work programs for individuals with schizophrenia (Bryson Lysaker, & Bell, 2002). In one study, 82% of schizophrenic participants were unable to find paid work outside the work program initiated for the study (Bryson et al., 2002).

HAPA model to improve depressive symptoms[edit | edit source]

Figure 4. Health Action Process Approach Model

The Health Action Process Approach (HAPA) model (see Figure 4) (Schwarzer, Lippke & Luszczynska, 2011) is a self-regulation framework that provides a distinction between goal setting and goal pursuit (Schwarzer et al., 2011). Researchers now suggest the model be applied to the study of depressive symptoms (Kramer, Helmes & Bengel, 2014). In the goal setting (motivational) phase, the HAPA suggests that risk perception, task self-efficacy and outcome expectations are involved. In the goal pursuit (volitional) phase, planning, action control and maintenance are involved (Schwarzer et al., 2011). The model suggests that participants experiencing one sub-type of activity limitation (motivational or volitional) should not be treated with the same therapeutic means (Kramer et al., 2014). Individuals with motivational deficits may benefit from treatment focusing on outcome expectations and self-efficacy. Cognitive restructuring could be utilised to improve negative outcome expectations. Moreover, emphasising personal goals and values may increase positive outcome expectations for motivational effected individuals. For volitional effected individuals, creating an action plan to initiate and continue already motivated intentions could be applied to assist maintain motivation (Kramer et al., 2014).

Managing side effects of anti-psychotics[edit | edit source]

Due to the improvement of positive and negative symptoms seen in schizophrenic patients after anti-psychotic treatment has been administered, removal of treatment via these medications is not likely. Instead, rigorously monitoring of dosage in order to identify a specific balance of dosage for each individual has been suggested to reduce negative side effects (McCann et al., 2008).

Improving physical health[edit | edit source]

Increasing knowledge regarding healthy food options and nutrition along with learning healthier coping skills in relation to eating when depressed could assists schizophrenic individuals improve diet and eating behaviours (Klingaman et al., 2014). Further to this, skill improvement programs could be carried out. For example, implementing programs such as cooking classes could assist schizophrenic individuals in preparing healthier meals. Additionally, creating gym programs that are enjoyable can help with motivation to exercise for individuals who are feeling depressed, fatigued and Amotivated (Klingaman et al., 2014).

Conclusion[edit | edit source]

Schizophrenia is a mental illness that can severely impact the social, occupational and educational lives of individuals effected. Moreover, schizophrenia impedes motivation greatly. These motivational deficits can have further negative effects on individual’s daily living. Three factors seem to contribute to motivational deficits seen in schizophrenic individuals. Negative symptoms of schizophrenia (Hartmann et al.,2015; Gard et al., 2014; Barch et al., 2014; Gard et al., 2007) co-morbid depression (Sands & Harrow, 1999; Dickson et al.,2011) and medication side effects (McCann et al., 2008; Voruganti, & Awad, 2004). Researchers suggest that breaking goals down into smaller, more pleasurable goals could improve self-competent beliefs after goal attainment and in turn, improve motivation to initiate and continue, goal oriented behaviour (Gard et al., 2014). Paid work is an additional practical solution suggested to improve motivation by allowing schizophrenic individuals to engage in meaningful work that involves reward (Bell et al., 1993). Additionally, monitoring medication dosages to insure management of negative side-effects has been suggested (McCann et al., 2008).

Motivation has been consistently low in schizophrenic individuals, however, there are many possible solutions for increasing not only motivation but health and well-being for these individuals in the future.

Quiz[edit | edit source]

1 The three symptom domains of schizophrenia are?

positive, cognitive and delusions
positive, negative and cognitive
negative, hallucinations and positive

2 Onset of schizophrenia is typically between ages?

late teens to 50s
early teens to mid 40s
late teens to mid 30s

3 The self-determination theory proposes two main types of motivation, intrinsic and extrinsic.

True
False

4 3 main features impact motivation in schizophrenic individuals, these are?

negative symptoms, co-morbid depression and medication side-effects
positive symptoms, co-morbid depression and obesity
co-morbid depression, obesity and self-competent beliefs

5 Paid work can act as a positive incentive to increase motivation in schizophrenic individuals.

True
False


See also[edit | edit source]

References[edit | edit source]

1+

American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author. DC

Bandura, A., & Schunk, D. H. (1981). Cultivating competence, self-efficacy, and intrinsic interest through proximal self-motivation. Journal of Personality and Social Psychology, 41(3), 586-598. doi:10.1037/0022-3514.41.3.586

Barch, D. M., Treadway, M. T., & Schoen, N. (2014). Effort, anhedonia, and function in schizophrenia: Reduced effort allocation predicts amotivation and functional impairment. Journal of Abnormal Psychology, 123(2), 387-397. doi:10.1037/a003629910.1037/a0036299.supp (Supplemental)

Bassett, A. S., Chow, E. W. C., O'Neill, S., & Brzustowicz, L. M. (2001). Genetic insights into the neurodevelopmental hypothesis of schizophrenia. Schizophrenia Bulletin, 27(3), 417-430.

Beck, A. T., Grant, P. M., Huh, G. A., Perivoliotis, D., & Chang, N. A. (2013). Dysfunctional attitudes and expectancies in deficit syndrom in schizophrenia.Schizophrenia Bulletin, 39(1), 43-51. doi:10.1093/schbul/sbr040

Bell, M. D., Milstein, R. M., & Lysaker, P. H. (1993). Pay and participation in work activity: Clinical benefits for clients with schizophrenia. Psychosocial Rehabilitation Journal, 17(2), 173-177. doi:10.1037/h0095590

Boydell, K. M., Gladstone, B. M., & Volpe, T. (2003). Interpreting narratives of motivation and schizophrenia: A biopsychosocial understanding. Psychiatric Rehabilitation Journal, 26(4), 422-426. doi:10.2975/26.2003.422.426

Bryson, G., Lysaker, P., & Bell, M. (2002). Quality of life benefits of paid work activity in schizophrenia. Schizophrenia Bulletin, 28(2), 249-257.

Choi, J., Fiszdon, J. M., & Medalia, A. (2010). Expectancy-value theory in persistence of learning effects in schizophrenia: Role of task value and perceived competency. Schizophrenia Bulletin, 36(5), 957-965. doi:10.1093/schbul/sbq078

Dickson, J. M., Moberly, N. J., & Kinderman, P. (2011). Depressed people are not less motivated by personal goals but are more pessimistic about attaining them. Journal of Abnormal Psychology, 120(4), 975-980. doi:10.1037/a0023665

Eccles, J. S. W. A. (2002). MOTIVATIONAL BELIEFS, VALUES, AND GOALS. Annual Review of Psychology, 53(1), 109.

Gard, D. E., Sanchez, A. H., Cooper, K., Fisher, M., Garrett, C., & Vinogradov, S. (2014). Do people with schizophrenia have difficulty anticipating pleasure, engaging in effortful behavior, or both? Journal of Abnormal Psychology, 123(4), 771-782. doi:10.1037/abn000000

Gard, D. E., Sanchez, A. H., Starr, J., Cooper, S., Fisher, M., Rowlands, A., & Vinogradov, S. (2014). Using self-determination theory to understand motivation deficits in schizophrenia: The 'why' of motivated behavior.Schizophrenia Research, 156(2-3), 217-222. doi:10.1016/j.schres.2014.04.027

Gard, D. E., Gard, M. G., Kring, A. M., Horan, W. P., & Green, M. F. (2007). Anhedonia in schizophrenia: Distinctions between anticipatory and consummatory pleasure. Schizophrenia Research, 93(1), 253-260. doi:10.1016/j.schres.2007.03.008

Hartmann, M. N., Kluge, A., Kalis, A., Mojzisch, A., Tobler, P. N., & Kaiser, S. (2015). Apathy in schizophrenia as a deficit in the generation of options for action. Journal of Abnormal Psychology, 124(2), 309-318. doi:10.1037/abn000004810.1037/abn0000048

Insel, T. R. (2010). Rethinking schizophrenia. Nature, 468(7321), 187-193. doi:10.1038/nature09552

Klingaman, E. A., Viverito, K. M., Medoff, D. R., Hoffmann, R. M., & Goldberg, R. W. (2014). Strategies, barriers, and motivation for weight loss among veterans living with schizophrenia. Psychiatric Rehabilitation Journal, 37(4), 270-276. doi:10.1037/prj0000084

Kramer, L. V., Helmes, A. W., & Bengel, J. (2014). Understanding activity limitations in depression: Integrating the concepts of motivation and volition from health psychology into clinical psychology. European Psychologist, 19(4), 278-288. doi:10.1027/1016-9040/a000205

McCann, T. V., Clark, E., & Lu, S. (2009). Subjective side effects of antipsychotics and medication adherence in people with schizophrenia. Journal of Advanced Nursing, 65(3), 534-543 510p. doi:10.1111/j.1365-2648.2008.04906.x

Muench, J., & Hamer, A. M. (2010). Adverse effects of antipsychotic medications. American family physician, 81(5), 617-622.

Nakagami, E., Xie, B., Hoe, M., & Brekke, J. S. (2008). Intrinsic motivation, neurocognition and psychosocial functioning in schizophrenia: Testing mediator and moderator effects. Schizophrenia Research, 105(1), 95-104. doi:10.1016/j.schres.2008.06.015

Reichenberg, A., Rieckmann, N., & Harvey, P. D. (2005). Stability in schizophrenia symptoms over time: Findings from the Mount Sinai Pilgrim Psychiatric Center Longitudinal Study. Journal of Abnormal Psychology, 114(3), 363-372. doi:10.1037/0021-843X.114.3.363

Ryan, R. M., & Deci, E. L. (2000). Intrinsic and extrinsic motivations: Classic definitions and new directions.Contemporary Educational Psychology, 25(1), 54-67. doi:10.1006/ceps.1999.1020

Sands, J. R., & Harrow, M. (1999). Depression during the longitudinal course of schizophrenia. Schizophrenia Bulletin, 25(1), 157-171.

Schwarzer, R., Lippke, S., & Luszczynska, A. (2011). Mechanisms of health behavior change in persons with chronic illness or disability: The Health Action Process Approach (HAPA). Rehabilitation Psychology, 56(3), 161-170. doi:10.1037/a0024509

van Os, J., & Kapur, S. (2009). schizophrenia. The Lancet,374(9690), 635-645. doi:10.1016/S0140-6736(09)60995-8

External Links[edit | edit source]