Objective
This study tested the relationship between metacognitive factors, intolerance of uncertainty, anxiety, and the predictability of, and distress associated with, acute fluctuations in symptoms in idiopathic Parkinson's disease (PD), when controlling for disease parameters.
Method
106 adults with idiopathic PD (30 females; Mage = 65.3; 90% white) participated in this study, with 93 of them reported experiencing off-periods. A cross-sectional design was employed that utilised: the Hospital Depression and Anxiety Scale, Movement Disorder Society revision of the Unified Parkinson's Disease Rating Scale, the Addenbrooke's Cognitive Examination — Revised, the Intolerance of Uncertainty Scale, and the Metacognitions Questionnaire 30. Correlation analyses, hierarchical regression analysis, and ordinal regression analysis were used to test the experimental hypotheses.
Results
Anxiety was not significantly associated with motor symptom severity or cognitive functioning, while metacognitive factors were significantly related to anxiety when controlling for motor experiences of daily living and intolerance of uncertainty, R2 = 0.56, F(1,82) = 15.04, p < 0.001 (adjusted R2 = 0.53). For participants with motor fluctuations, no association was found between predictability of, and distress associated with, off-periods. Metacognitions concerning uncontrollability and danger were significantly related to off-period distress when controlling for motor experiences of daily living, intolerance of uncertainty, and other metacognitive factors, χ2(1) = 20.52, p = 0.001.
Conclusion
Metacognitive factors play a role in anxiety and off-period distress in PD and this is discussed in terms of the Self-Regulatory Executive Function model. Interventions from metacognitive therapy are potential means to ameliorate off-period distress and anxiety in PD.
Parkinson's disease (PD) is a progressive neurological disorder with an estimated population prevalence of approximately 300 per 100,000, increasing to 1%, over the age of 60 years and up to 4% in the oldest age groups [1]. PD is typically considered a disorder of movement with symptoms of slowed and reduced amplitude voluntary action, tremor, and rigidity affecting limb and eye movement, in addition impaired control of balance, swallowing, and speech. A range of disabling non-motor symptoms are also commonly experienced including depression, anxiety, psychosis, cognitive impairment, autonomic dysfunction, fatigue, and pain. Motor and non-motor disability increase with disease progression despite symptomatic treatment using levodopa, dopamine agonists, or other drugs that modify brain dopamine levels. With disease progression and increasing duration of treatment, effectiveness gradually declines. In those treated with levodopa, fluctuations in symptom severity over the course of the day commonly develop. These include ‘wearing off’ (a relatively predictable re-emergence of symptoms towards the end of a medication dose); ‘on/off fluctuations’ (unpredictable and sudden recurrence of Parkinsonian symptoms); ‘delayed on’ (unpredictably increased time between ingestion of a dose and motor benefit), and ‘dose failure’ (unpredictable failure of a dose to provide usual benefit) [2]. In addition to worsening of motor symptoms during ‘off-periods’, the emergence or exacerbation of distressing non-motor symptoms is also reported by many individuals including pain, fatigue, drenching sweats, depression, and anxiety.
Currently, fluctuations and associated symptoms are managed by alterations in drug regimen but this becomes increasingly difficult with disease progression. This offers potential to develop adjunctive psychological approaches to manage individual symptoms (e.g. depressed mood, pain, or fatigue) or reduce the level of associated subjective distress. There is evidence that traditional CBT treatment approaches can be helpful in reducing depressive and anxiety symptoms in PD [3] and [4] although not specifically in the context of motor fluctuations. One challenge of CBT is the limits on reality-testing of thoughts and beliefs about PD (e.g. ‘there is no cure for this disease’ or ‘I have no control over my symptoms’) as these may represent accurate appraisals of the disease, and may be challenging to test during ‘in the moment’ distress associated with off-periods. Key to developing a more targeted therapy is an understanding of the cognitive and attentional processes that contribute to the emotional difficulties experienced by some with PD including those associated with off-period distress. We propose that metacognitive therapy (MCT) [5], an effective treatment for depression and anxiety [6] may be particularly well-suited to the management of PD distress. MCT is based on the Self-Regulatory Executive Function model (S-REF) [7] and posits that psychological distress results from perseverative cognitive processes (e.g. rumination and worry) and attentional strategies (e.g. symptom focussing and hypervigilance). These are proposed to be governed by both explicit and implicit metacognitions and form a Cognitive Attentional Syndrome (CAS). Preliminary research has implicated metacognitions in distress in a small sample of people with PD [8]. S-REF proposes that specific CAS configurations are activated in response to inner events such as cognitions (including memories), emotions, and physical states. If an individual with PD experiences symptoms associated with an off-period and endorses positive metabeliefs about worry (e.g. “worry helps me to solve problems”), the response to this off-related symptom will be worry. An individual who holds negative beliefs about worry, such as ‘my worry is uncontrollable’, may be less inclined to make attempts to halt this cognitive process and instead to ‘worry about worry’, increasing distress further and helping to drive more worry. In both instances a stop-signal for this process is not received (i.e. the goal of solving a problem), resulting in worry perseveration and distress. The modifications of the metacognitions that are hypothesized to fuel maladaptive CAS configurations are a key target of MCT interventions.
In this study, we test the following hypothesis: that metacognitive factors explain a significant proportion of variance in anxiety and off-period distress after controlling for disease characteristics, cognitive function, off-period predictability, and trait intolerance of uncertainty.
