The relationship of depression and disease stage to patient perceptions of Parkinson’s disease

Abstract

The present study aimed to perform an in-depth exploration of perceptions of Parkinson’s disease (PD) and their relationship to depression and disease stage using semi-structured interviews. 37 participants with PD formed four groups: depressed and non-depressed with either mild or moderate-severe stage PD. Interviews were analysed using Framework Analysis. Moderate-severe stage patients reported a greater variety of perceptions than those with mild symptoms. Depressed and non-depressed patients differed in their perceptions of the consequences, treatment control and emotional reaction to PD. Helping patients to adjust life goals to accommodate PD and employ adaptive coping strategies may help to relieve depressive symptoms in PD.

Keywords

Illness perceptions beliefs Parkinson’s disease depression Common-sense model

Introduction

Parkinson’s disease (PD) is a chronic, degenerative neurological condition affecting approximately 120,000 people in the UK (Parkinson’s Disease Society, 2007). The disease is characterized by motor symptoms including tremor, slowness and rigidity but also involves non-motor symptoms including, amongst others, mood and other psychiatric symptoms, cognitive impairment, gastro-intestinal dysfunction, autonomic dysfunction and sleep disturbance (Chaudhuri et al., 2006a, Chaudhuri et al., 2006b). Anxiety and depression have a high prevalence and are associated with poor quality of life (Gallagher et al., 2010; Schrag et al., 2000), yet relatively little is known about the factors involved in their development and maintenance. While they may be due in part to neurobiological changes in the brain and/or consequences of a chronic and disabling illness they are neither inevitable nor experienced by all patients.

Patient well-being and adjustment to illness are known to be associated with disease-related disability and handicap (e.g.Prince et al., 1998). However social cognition theories of health behaviour have demonstrated the importance of patient beliefs in determining well-being and adjustment independent of such factors (Sharpe and Curran, 2006). In the Common-Sense Model of Illness Representation (CSM) (Leventhal et al., 1984) people react to and cope with threats to their health through personal models of illness. These develop from emotional and cognitive processing of illness-related information and are derived from a variety of sources including health professionals, the media, personal experience and lay information from friends and family. Cognitive representations consist of beliefs which fall into five broad dimensions: identity (symptoms and label), cause, consequences, control, and timeline (Lau and Hartman, 1983; Leventhal et al., 1984). These can in turn interact with the emotional representations. Together, these personal representations determine which coping strategies patients choose to use to deal with health threats. The CSM is dynamic in nature; the efficacy of chosen coping strategies is appraised which may lead to changes in beliefs and subsequently choice of coping strategy. A meta-analysis of illness perception studies has shown that perceptions of low control, high consequences and longer timeline beliefs, are consistently associated with greater distress across a range of physical health problems (Hagger and Orbell, 2003). Most research is cross-sectional in design, making it difficult to establish the directionality of causal links between illness perceptions and disease-related distress or broader outcomes such as depression. However, Dickens et al. (2008) carried out a prospective study of first time heart attack patients and showed that those who held negative beliefs about cure/control and timeline at baseline were more likely to become depressed over the following year. Likewise illness perceptions have been found to longitudinally predict depression in oesophageal and head and neck cancer survivors (Dempster et al., 2011; Llewellyn et al., 2007).

Based on the assumptions of the CSM it would be expected that cognitive and emotional representations held by patients would change over the course of their illness as a consequence of their greater illness experience. While several studies have shown such change over time (Bijsterbosch et al., 2009; Kaptein et al., 2010), little is known about the process of such change (Fischer et al., 2010; Scott et al., 2007). Although models of illness by their nature are particular to the individual, some consistent differences may be found between those in early and later stages of a disease.

Furthermore, if illness perceptions inform adjustment and well-being via coping, it would be expected that models of illness held by those with depressed or anxious mood would differ from those without mood disturbance (e.g. Dickens et al, 2008).

There has been little research into patient perceptions of PD. A recent quantitative investigation found perceptions of serious consequences, negative emotional representation and low personal control of PD predicted greater anxiety and depression (Evans and Norman, 2009). The present study sought to investigate cognitive models of PD in early and later stage disease and their relationship to depression. The CSM was used as a framework to guide the examination of patient perceptions.

Methods

Participants

Participants were recruited from a cohort of patients participating in a prospective study of mood states in Parkinson’s disease (PROMS-PD) (Brown et al., 2011). Patients were excluded if they had severe sensory loss (hearing or vision) or communication difficulties that would interfere with the assessment or scored ≤ 23 on the Mini-Mental State Examination (Folstein et al., 1975). A purposive sample of 37 patients diagnosed with PD were divided into four groups: (i). Mild PD, non-depressed (N = 10); (ii). Moderate-severe PD, non-depressed (N = 10); (iii). Mild PD, depressed (N = 8), and (iv). Moderate-severe PD, depressed (N = 9) (see Measures below for group definitions). Across the groups participants were matched for sex and age within three years. Participants were visited at home by a researcher (CH). Written consent was obtained from all participants (Ethics ref:08/H0808/65).

Measures

Perceptions of PD were elicited using a semi-structured interview based on previous studies of illness perceptions (Hurt et al., 2010; Lau et al., 1989; Lobban et al., 2005; Scott et al., 2007). The interview began with an open-ended question prompting patients to describe their experience of PD (“Can you tell me about your experience of having PD?”). This section of the interview was followed by a series of questions exploring the dimensions of illness perception measured in the Illness Perception Questionnaire–Revised (Moss-Morris et al., 2002) (e.g. “what have been the consequences (i.e. effect on your life) for you of having PD?”). These dimensions are an elaboration on the original five themes of beliefs described by Leventhal et al., (1984) to include: identity (symptoms and label), timeline cyclical, timeline acute/chronic, personal control, treatment control, illness coherence (understanding of illness), emotional representation, consequences and cause. The final section of the interview consisted of a series of questions designed to investigate changes in personal models of PD focusing on the identification of triggers for change (e.g. [Referring to perceptions discussed] “Have you always thought that? Did you feel that way when you were first diagnosed? Do you remember when you changed your mind?”). (A copy of the interview schedule is available from the corresponding author on request).

Mood

The Hospital Anxiety and Depression Scale (HADS) (Zigmond and Snaith, 1983) is a 14 item self report measure. Subscale scores of 8-10 indicate ‘possible’ depression or anxiety, and 11+ a ‘definite’ problem. The HADS has been validated for use in PD (Marinus et al., 2002; Mondolo et al., 2006). For the present study patients were defined as depressed if their HADS score was ≥ 8.

Disease severity and stage

The Unified Parkinson’s Disease Rating Scale (UPDRS) (Fahn et al., 1987) is a clinician-rated measure of severity of PD motor symptoms. Higher scores indicate greater motor dysfunction. The UPDRS has excellent validity and reliability (Stebbins et al., 1999). The Hoehn and Yahr scale gives an overall rating of disease severity. Stages 1-2 indicate mild disease, and 3–5 indicate moderate to severe disease. For the present study the Hoehn and Yahr stage was used to define the groups.

Qualitative analysis

Deductive Framework Analysis (Ritchie and Spencer, 1994), previously applied in illness perception research (Scott et al., 2007), was used to sort and index statements within the framework provided by the interview. Instances of themes were recorded using that software package NVivo (Version 8.1 QSR International, PTY. Ltd.). Ten percent of the transcripts were indexed by an independent researcher who showed high consistency with the original indexing. Most disagreements arose when coding a statement as consequences or emotional representation e.g. “it enforced my early retirement from work. That was a great disappointment and a great shock because I had anticipated working to 65”. After discussion it was decided that this statement centred on the consequence of having to give up work, the emotions expressed were associated with giving up work rather than PD per se. Instances were then charted or organised by theme. The final stage of the analysis, mapping and interpretation, involved the identification of patterns, key differences and explanations within the data. Framework Analysis was selected due to its structured method and suitability for research with a clear a priori framework.

Results

Table 1 shows the clinical and demographic factors for the four groups. ANOVA, Kruskal-Wallis test and chi-squared were used to compare variables between groups. Significant differences were highlighted using post-hoc tests. The groups did not differ significantly in terms of age, gender, disease duration, medication, marital status or household income.

Table 1.

Demographic and Clinical Characteristics

	N	Sex	Age (years) Mean (SD)	Duration of PD (years) Mean (SD)	H&Y Mean (SD)	HADS Depression Mean (SD)	HADS Anxiety Mean (SD)	HADS Total Score Mean (SD)	Marital Status (% married)	Household Income Mean (SD)	Patient attended higher education N (%)	LEDD Median (IR)
Mild PD, not depressed	10	5 males 5 females	63.5 (6.8)	7.4 (1.7)	2 (.0)	3.6 (2.2)	5.3 (2.7)	8.9 (4.0)	70	3.6 (2.2)	6 (60)	800 (498.5)
Moderate-severe PD, not depressed	10	5 males 5 females	68.6 (8.1)	9.0 (3.9)	3.2 (.4)	2.8 (2.2)	5.2 (4.1)	7.9 (4.8)	90	1.7 (0.9)	4 (40)	1254.6 (964.5)
Mild PD, depressed	8	5 males 3 females	66.4 (5.6)	6.9 (4.0)	2.0 (.0)	10.0 (3.3)	8.9 (3.6)	18.9 (6.1)	75	2.5 (1.4)	5 (50)	695 (622.8)
Moderate-severe PD, depressed	9	4 males 5 females	66.1 (8.1)	10.1 (4.3)	3.3 (.7)	11.8 (2.3)	10.1 (4.0)	22.0 (5.2)	56	2.6 (1.9)	3 (33.3)	800 (755.5)
Total sample	37	19 males 18 females	66.1 (7.2)	8.3 (3.6)	2.7 (.8)	6.8 (4.6)	7.2 (4.1)	14.0 (7.9)	73	2.6 (1.8)	17 (45.9)	831.3 (645)
Group differences	–	χ² =.585 p=.900	F=.820 p = .492	F=1.474, p = .240	F= 29.135, p ≤.001	F=29.8, p ≤.001	F = 4.217, p = .013	F = 18.428, p ≤.001	χ² =1.090 p=.297	F = 1.529, p = .231	χ² =1.567 p=.667	H₃=6.85 P = .077

Notes: H&Y = Hoehn and Yahr Disease Staging, higher score = greater severity

HADS = Hospital Anxiety and Depression Scale, higher score = greater severity

Household income = 6 point rating based on the Office of National Statistics Pensioners Income Series (2004/2005), higher score = greater income

LEDD=Levodopa Equivalent Daily Dose, a standardised measure of medication

SD= Standard deviation

IR = Interquartile range

Each illness perception dimension was examined individually. Distinctive themes identified in each dimension are summarized in tables 2 -4, with examples.

Table 2.

Distinctive themes identified in illness perception dimensions Causal Beliefs and Consequences, with examples

	Depressed	Non Depressed
Causal Beliefs
Early stage	- Uncertainty- Punishment (Viewed PD as a punishment) “…it would be nice to know if I have done something wrong, said wrong words or something”	- Uncertainty- Punishment (Viewed PD as a punishment)
Late stage	- Uncertainty “Well I thought it might have been because I fainted some years ago and hit my head on a stone floor. Whether or not that contributed to it I don’t know.” - Neurological cause (Reference to loss of brain dopamine) “I know that the dopamine is gradually going and going and going and you can’t get it back.”	- Uncertainty- Neurological cause (Reference to loss of brain dopamine)
Consequences
Early Stage	- Avoidance of activities (References to staying at home/giving up activities because of PD) “I carry on doing what I can do but I always I’m afraid of not being well so sometimes you say I’d rather stay at home.”	- Current activities (References to activities that they are still able to do) “I still go out, I still go out to dinner and things like that.”- Life changes (Reference to changes to routines, hobbies etc to accommodate PD) “It’s just there and you’ve got to work your life around it.”- Positive consequences of having PD. “You react to beggars … if I’ve got any change I’ll hand it over but often I … do now speak to people rather than just throwing some money in their hat … I think that it’s to be acknowledged as a human being to a lot of people is more important … I’m probably more likely to do it now which Parkinson’s has quite possibly taught me.”
Late stage	- Wide and varied range of consequences reported- Avoidance of activities (References to staying at home/giving up activities because of PD)	- Wide and varied range of consequences reported- Current activities (References to activities they are still able to do)- Life changes (References to changes to routines, hobbies etc to accommodate PD- Positive consequences of having PD

Table 3.

Distinctive themes identified in illness perception dimensions Emotional Representations, Identity and Personal Control, with examples

	Depressed	Non Depressed
Emotional Representations
Early stage	- Negative emotional representations, anger and frustration. “If I suddenly get a moment when I think about it I get angry but not every day, just occasionally.”	- Negative emotional representations, anger and frustration- Realism (Reference to realistic about the future rather than pessimistic)
Late stage	- Negative emotional representations, anger and frustration	- Negative emotional representations, anger and frustration- Realism (Reference to realistic about the future rather than pessimistic) “But I don’t feel that, I feel that apart from Parkinson’s we have a very happy life. … I don’t feel pessimistic because I know that’s the way it’s got to go. It’s being realistic.”
Identity
Early stage	- Reported motor and non-motor symptoms “all of the ones so far as I say is the tremors and this lethargy.”	- Reported motor and non-motor symptoms- Is it PD? (References to difficulty distinguishing symptoms of PD and other illnesses) “It’s difficult sometimes for me to be sure whether it is the arthritis that is causing the problems or whether it is actually down to the Parkinson’s itself”
Late stage	- Reported motor and non-motor symptoms- Greater range of symptoms reported	- Reported motor and non-motor symptoms- Greater range of symptoms reported- Is it PD? (References to difficulty distinguishing symptoms of PD and other illnesses
Personal Control
Early stage	- Methods, ways to control PD “walk with a walking stick sometimes just to get the rhythm to get your legs, long paces, rather than stuttering along”- No control at all	- Methods, ways to control PD- No control at all
Late stage	- Methods, ways to control PD- No control at all	- Methods, ways to control PD- No control at all “Well, not really…If I thought there was anything I could be doing that would improve me I’d be doing it.”

Table 4.

Distinctive themes identified in illness perception dimensions Timeline and Treatment Control, with examples

	Depressed	Non Depressed
Timeline
Early stage	- Worsen with time	- Worsen with time- Miracle treatment (References to a future treatment or cure) “[I will have Parkinson’s] till I die. Well, I say that [of] course there are different ways of looking at that. There may be some miracle drug that will arrive…” - Cyclical nature, good days and bad days
Late stage	- Worsen with time “I know it’s not going to go away and I know there’s no cure for it. They can slow it down a bit…so that I get a bit more quality out of life for a few more years. I know eventually I will end up in a wheelchair and I won’t be able to go anywhere, not without somebody pushing me…”	- Worsen with time- Miracle treatment (References to a future treatment or cure)- Cyclical nature, good days and bad days “Some days my symptoms will be good and you wouldn’t know that I had anything wrong with me and another day I will be, not exactly a gibbering wreck, but not at my best.”
Treatment Control
Early stage	- Dissatisfaction with care “If they kept to appointments so that you knew if you were getting worse and one thing and another. If I’d have gone before I think the last 6 months I might have had something done about this choking…” - Never had effective drugs- Wishful thinking “I wish there was something that I could take or do that would help me better get through the day” - Friends and family lack understanding “I think sort of be more understanding, maybe my son, if I’m walking along the road he marches off and it’s only when I tell him to wait for me that, he doesn’t seem aware, he seems to think I can catch up and I get quite cross with that.”	- Friends and family helpful
Late stage	- Dissatisfaction with care- Never had effective drugs- Wishful thinking- Friends and family lack understanding	- Friends & family helpful “Support wise … I’ve too good a crew beside me, my wife is perfect, my daughter, my son, I couldn’t have anymore backing.”

Cause

When discussing the personal cause of PD all participants made reference to “not knowing”. Possible causes suggested included exposure to chemicals, stress, past accidents and hereditary factors but none were offered with any certainty or conviction. Two participants in the moderate-severe groups made reference to loss of brain dopamine as the biological cause of PD symptoms, a factor not mentioned in the mild groups. This may be a reflection of their increased knowledge of the disease.

Participants from all groups made reference to chance in the development of PD (N = 5). Two, with mild PD, made reference to it being a “punishment”. It is possible that these specific cognitions represent a stage in the process of adjustment and acceptance. The early stages of adjustment often involve acute distress and despair (Barraclough, 1994). However, the “punishment” beliefs did not appear to be a specifically depression related cognition.

Consequences

Reported consequences of PD were predominantly negative and encompassed changes in employment, relationships, activities and personality. The moderate-severe groups reported a greater range of consequences than the mild groups and with greater personal impact. Non-depressed patients also referred to things they could still do (N = 9), reported finding alternative activities or ways of doing things (N = 7) and even mentioned positive consequences of having PD (N = 2) (e.g. developing a more positive attitude towards others). Contrastingly, depressed participants (both mild and moderate-severe) often reported avoidance of activities by staying at home or putting things off (N = 6). Non-depressed participants did not report such avoidance.

The consequence of needing to change their lifestyle shows a much more adaptive approach in the non-depressed patients. By continuing to participate in activities patients may continue to feel a sense of self-worth, maintain confidence and social contacts. In contrast, avoidance and withdrawal could lead to a sense of loss of role and a reduction in social contact, which are associated with depression (e.g. Jang et al., 2002; Peirce et al., 2000; Zietemann et al., 2007). There is a clear link between the perceptions of consequences (“PD means I can’t do the things I used to do” vs. “PD means I have to change the things I do”), how these impact on coping (stay at home vs. find new activities) and mood (depressed vs. non-depressed).

Emotional representation

Negative emotional representations were common across all groups (68% participants), particularly anger and frustration. The non-depressed group expressed such emotions but also understood that they were “realistic”, and to be “expected” (N = 4), and made distinctions between their general feelings and feelings about PD (“happy except for PD”). Such perceptions were not expressed by the depressed group whose emotional statements were more globally negative and generalized. The realism reported by non-depressed patients may be related to their better psychological well-being and use of adaptive coping strategies. However, being overly optimistic can be detrimental (de Ridder et al., 2000), perhaps as reflected in the report of one depressed patient as “not being worried” by their PD.

Identity

A large range of symptoms including motor and non-motor symptoms were reported in all groups. As would be expected the moderate-severe groups reported a greater range of symptoms. The non-depressed group more frequently reported having difficulty separating the symptoms of PD, particularly the non-motor symptoms, from other illnesses and medication side-effects (Non-depressed, N = 10; Depressed, N = 3)

Personal control

All groups reported attempts to take personal control over their PD (68% participants) including relaxing, taking medication on time, exercising and not doing too much. In line with the CSM the moderate-severe groups reported a greater variety of personal coping strategies which may be a result of attempts at coping with more severe symptoms and their consequences. Thirty-two percent of the sample reported having no sense of personal control over their PD, but this was not clearly linked to depression status.

Illness coherence

Illness coherence was a less common cognition, only 12 participants made statements concerning their understanding of PD. In the moderate-severe depressed group two participants voiced a lack of understanding about the treatment of PD, asking if medication can really control PD. Again we see a potential link between perceptions and outcome, perceived lack of control over illness has been associated with poorer well-being.

In both mild groups illness coherence cognitions tended to centre on the cause of PD and difficulty accepting having a disease when they can’t understand why they have developed it (N = 4). No lack of understanding of PD was expressed by the moderate-severe non-depressed group.

Timeline

All participants were aware that there is no cure for PD. All groups reported the belief that PD would become worse over time (depressed N = 6; non-depressed, N = 5). However a notable difference was seen in depressed and non-depressed patients’ future expectations. Four non-depressed patients expressed hope for a “miracle” new treatment to relieve symptoms or perhaps cure their PD. However, this was expressed more as a “daydream” and was underpinned by realism that major advances in treatment were always said to be “5-10 years away”. Six non-depressed participants described a short-term cyclical timeline with PD symptoms changing from day to day, with good days and bad. No patients indicated a long-term cyclical expectation.

Treatment control (drugs and medical staff)

Participants made many statements regarding the importance of medication in the control of PD symptoms. Participants in all groups referred to the idea of “living by the clock” (N = 6) and frequently changing drugs to find the best combination (N = 9). Six participants, all from the depressed sample, reported that none of the drugs they had been prescribed for their Parkinson’s had ever been effective at alleviating symptoms and had experienced significant side effects.

Negative statements about medical staff and care received were infrequent and mainly expressed by depressed participants (N = 5). Three non-depressed patients expressed a positive opinion of their care team.

Treatment control (friends and family)

A marked contrast was seen in the perceptions of help by friends and family held by depressed and non-depressed patients. Non-depressed patients were positive about the help and understanding they received from friends and family (N = 10). Eight depressed patients held negative perceptions of friends and family, centred on a lack of understanding and their failure to make allowances for the participant’s PD.

Changes in perceptions

Changes in perceptions of PD over the course of the condition were reported by participants in all groups and in the following areas: consequences, personal control and emotional representation.

Changes in perceptions of consequences were most common (N = 12), from initially perceiving PD to have no/few consequences to later perceiving serious consequences. Mostly participants reported a lack of initial understanding, learning only gradually through personal experience of the disease and from others. Three participants reported a sudden change in perceived consequences following specific triggers: after an injury; after experiencing strange bodily sensations following taking medication, and after a stranger noticed the participant had PD.

Ten participants referred to changes in perceptions of personal control. Five reported loss of ability to control symptoms through concentration and increasing dependence on medication.

A contrast can be seen in the changes over time in emotional representation reported by depressed and non-depressed patients. Those in the non-depressed group described initial negative emotional reactions which later resolved, with patients “gradually accepting PD” (N = 3). In contrast depressed participants described positive initial reactions including relief that PD was not life threatening which became more negative with both experience of, and learning more about, the illness (N = 4). These changes again support the possible ways in which realism or unrealistic optimism may relate to outcome.

Discussion

The present study is the first, in-depth assessment of patient perceptions and their changes in PD, and their relationship to disease stage and mood through the qualitative exploration of cognitive models of PD in both depressed and non-depressed, and mild and moderate-severe disease stage patients. Participants provided rich and varied accounts of their experience of PD, with some commonalities across all groups, but difference depending on mood or disease stage, particularly in relation to perceptions of consequences, treatment control, emotion reaction and symptom attribution and support provided by others. The results provided support for the CSM as a useful explanatory framework for understanding the roles of cognitive and emotional representation, on coping and outcome.

Attempts were made to identify any changes that had occurred in patient perceptions. The moderate-severe sample displayed a greater range of perceptions. Changes seemed to occur gradually with greater experience of the disease, in agreement with the CSM, and as previously reported (Fischer et al., 2010). Of particular note were changes in emotional representation; the findings suggest that patients who initially hold unrealistic expectations of the impact that PD may have on their lives may be at greater risk of later depression as their PD progresses. This association seems consistent with previous research which suggests that patients given satisfactory information about PD at time of diagnosis display better health related quality of life at later time points (Findley et al., 2002). However the absence of longitudinal data in this study prevents conclusions being drawn about causal relationships between depression and initial reaction to diagnosis. It is possible these patients were already depressed at time of diagnosis or had a history of depression, longitudinal studies are needed to confirm these hypotheses.

Cognitive Behavioural Therapy (CBT) is being increasingly utilized in the treatment of depression in PD ( Dobkin et al., 2008, Dobkin et al., 2011; Farabaugh et al., 2010,) and other chronic progressive diseases such as multiple sclerosis (Rizzo et al., 2011). The efficacy of CBT in reducing depression supports the importance of targeting beliefs, attitudes and coping responses to improve mood (Dobkin et al., 2011). Although the direction of causality of the relationships between perceptions and mood is not clear the dynamic nature of the CSM suggests it is not important. Similarly, the cognitive-behavioural models underlying CBT assume a reciprocal relationship between beliefs, behaviour and mood. This permits an intervention aimed at cognitions or behaviour to change mood which in turn feeds back in terms of positive changes in the other components. The qualitative nature of this study compliments a previous quantitative study of perceptions in PD which found perceptions to be associated with depression and anxiety (Evans and Norman, 2009). The qualitative findings build on those of the quantitative study by highlighting specific cognitions associated with depression which could be targeted during therapy.

The results have a number of implications for therapeutic interventions. The process of adjustment to chronic illness requires individuals to readjust their schemas to match their new situation (Horowitz, 1986). For individuals with PD this may include “down-grading” goals, developing new hopes and devising new plans which are more realistic and achievable. Failure to readjust schemas can be interpreted as a failure to adjust to illness which is associated with poor psychological well-being. It is possible that the depressed participants in the present sample are failing to adjust their goals to be more realistic, leading to avoidance of tasks and subsequently depression. Interventions which aim to help patients reassess their abilities and set new goals may be beneficial in reducing depressive symptoms. The study also highlights the significance of avoidance as a possible risk factor for depression, making it an important target for intervention.

Depressed participants’ perception of family as lacking understanding of their PD and failing to make allowances for them suggests that interventions encompassing family members may be helpful to this group. Education for family members could help improve understanding of PD and thus patient-family interaction.

The results suggested that there may be a link between early positive reactions to diagnosis with PD, including overoptimistic expectations of the future, and later depression. Working with patients early after diagnosis may help to promote realism, encourage adaptation and aid long-term adjustment. Those patients who have unrealistic expectations for the future may benefit from brief CBT interventions to prevent later depression (Findley et al., 2002).

Promotion of realism in expectations of treatment efficacy may also be important for outcome through its impact on perceptions of control and beliefs about medical care. All participants who reported experiencing “no benefits” from medication were in the depressed group. Monitoring of patients who have unrealistic expectations or who struggle to find an effective treatment regime may allow the timely provision of interventions should patients begin to experience depressive symptoms.

Some limitations of the present study must be considered. It was not possible to achieve perfect sampling to match the four groups, with mild PD depressed women difficult to recruit. Depression was operationally defined using a HADS cut-off of eight which did not provide depressed groups with symptoms of a severity that might indicate the need for treatment. Recruiting patients with a clinical diagnosis of depression would have given greater validity to the mood differences between the two samples. Furthermore the present study did not collect data on duration of depressive symptoms preventing conclusions being drawn concerning the temporal relationship between illness representations and depression onset. However, despite these limitations, meaningful and interpretable differences were observed within the CSM framework. Future studies could better test the hypothesized relationships between depression and illness representations in a longitudinal study recruiting patients with clinically diagnosed depression.

This is a small sample qualitative study and although the data suggests clear links between perceptions and mood disorder, generalizations cannot be made. Large-scale longitudinal studies are required to confirm some of the relationships hypothesized in this article. Furthermore greater insights could be made into the mechanisms of changes in perceptions by following patients longitudinally.

The aim of the present study was to examine the dimensions of the CSM. While this provided a clear structure for the analysis and provides further validity for the CSM in PD the study did not explore themes outside the CSM that may have differed between patient groups. Future research would benefit from exploring themes outside those of the CSM using inductive methods to complement the deductive approach used here.

Finally, changes in illness perceptions were measured retrospectively in the present study. Patients’ recall of their initial perceptions of PD may have been biased by subsequent experience and information and their recall not entirely accurate. This should be considered when interpreting the results and again could be addressed in future longitudinal studies.

Conclusions

Through a guided interview patients with PD were able to provide detailed accounts of their illness experience. The findings suggest that emotional and cognitive representations of PD may be important determinants of (and reciprocally related to) both adaption and avoidance, and mood. Assisting patients in achieving realistic expectations about longer term outcome and the effectiveness of treatment may help patients to adjust their goals and either prevent or reduce the risk of depression. The findings may have implications for the treatment of depression in a range of chronic progressive diseases.

Footnotes

Acknowledgements

The authors acknowledge support from: Parkinson’s UK; NIHR Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust (SLaM) and Institute of Psychiatry, King’s College London.

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