Internal Versus External Frame of Reference in Functional Movement Disorders
Publication: The Journal of Neuropsychiatry and Clinical Neurosciences
Abstract
Objective:
The purpose of this study was to determine whether patients with functional movement disorders (FMDs) differ in their internal versus external locus of control (LOC) and whether LOC in these patients affected disease severity, quality of life, and functional impairment compared with control subjects with degenerative (Parkinson’s disease) and nondegenerative (focal dystonia) neurological conditions.
Methods:
A total of 156 patients with FMD (N=45), Parkinson’s disease (N=64), and focal dystonia (N=47) were recruited between June 2015 and August 2017. The authors administered the general Levenson Multidimensional LOC (LOC-G) and health-specific Multidimensional Health LOC (LOC-H) scales. An internal LOC was represented similarly in both scales: the external LOC included “chance” and “powerful others” in the LOC-G measure and chance, “other people,” and “doctors” in the LOC-H measure. Quality of life, functional impairment, and FMD severity were assessed. One-way analysis of variance and adjusted logistic regressions were used, as well as ordinary least-squares between and within groups, respectively.
Results:
Patients with FMD had lower external chance LOC-G scores compared with patients in the Parkinson’s disease group (odds ratio=0.90, p=0.03) and higher internal (odds ratio=1.22, p=0.01) and lower external (odds ratio=0.77, p=0.02) doctors LOC-H scores compared with patients in the focal dystonia group. External powerful others LOC-G score was associated with functional impairment (regression coefficient=−0.04, p=0.02). There were no effects of LOC on quality of life or disease severity.
Conclusions:
Patients with FMD exhibited high “within our control” internal general and health-specific frame of reference. LOC had no influence on quality of life or disease severity in this patient population.
People attribute life events to either internal or external forces on the basis of their frame of reference, which can be measured by locus of control (LOC), a dimension of an individual’s personality core self-evaluation. Individuals with a high internal LOC believe that events are a consequence of their actions and therefore within their control, whereas individuals with a high external LOC believe that other people (including doctors), circumstances, or chance dictate life events, which are therefore beyond their control (1). Internal LOC has been associated with greater self-care and understanding of illness compared with external LOC (2). Greater external influence of others has been identified among patients with psychogenic nonepileptic seizures (PNES) compared with patients with temporal lobe epilepsy (3).
Functional movement disorders (FMDs) are commonly associated with disabling symptoms and poor prognosis (4, 5). If the frame of reference of a patient with FMD is based on factors beyond his or her control as an explanation for his or her problems, the patient is thought to have a high external LOC. Conversely, if a patient believes that it is his or her fault that life problems have developed, one would expect the patient to have a high internal LOC. We sought to determine the extent to which patients with FMD differ in their internal versus external general and health-specific LOC and whether LOC affects disease severity, quality of life, and functional impairment in these patients compared with control subjects with degenerative (Parkinson’s disease) and nondegenerative (focal dystonia) neurological conditions. In this first-of-its-kind study, we hypothesized that the frame of reference among FMD patients would be dependent on factors beyond their control (high external LOC) and have a negative effect on disease severity, quality of life, and functional impairment.
Methods
Study Design and Participants
For this cross-sectional study, consecutively consenting participants were recruited between June 2015 and August 2017 from the University of Cincinnati James J. and Joan A. Gardner Center for Parkinson’s Disease and Movement Disorders and the University of Louisville Movement Disorder Clinic. All diagnoses were made and delivered by two trained movement disorders neurology specialists (A.J.E. and K.L.). Eligibility criteria were age ≥18 years, with clinically definite FMD (6, 7), Parkinson’s disease (8), or focal dystonia (9). Patients who had cognitive impairment, who were pregnant, or who were unable to complete questionnaires were excluded.
This study was conducted in accordance with good clinical practice and the Declaration of Helsinki guidelines. The study protocol was approved by the institutional review boards of the University of Cincinnati and the University of Louisville. Written informed consent was obtained from all study participants.
Assessments
Frame of reference can be estimated for general aspects of life and for health-related behaviors (10, 11); while there may be an overlap, these variables are not exchangeable (12). Thus, all participants completed two self-administered LOC questionnaires: the Levenson Multidimensional Locus of Control Inventory (LOC-G) and the Multidimensional Health Locus of Control Assessment–Form C (LOC-H).
LOC-G is a 24-item general LOC scale. It consists of one internal (internal control) and two external (“chance” and “powerful others”) dimensions. The score range for each dimension is from 0 to 48, with higher scores indicating higher LOC per dimension (10).
LOC-H is an 18-item health-specific LOC scale. It consists of one internal and three external (“chance,” “doctors,” and “other people”) dimensions. For the internal dimension and the chance external dimension, the score range is from 6 to 36, and for the external dimensions of doctors and other people, the score range is from 3 to 18, with higher scores indicating higher LOC per dimension (12).
Additional measurement tools included the Toronto Alexithymia Scale-20, with a score ≥61 indicating alexithymia (13); the Positive and Negative Affect Schedule (PANAS), a psychometric questionnaire that independently measures positive and negative affect (i.e., the response to situations in a cheerful or distressed way, respectively) and is scored from 10 to 50 for each factor, with higher scores indicating greater affect (14); the Quality of Life Scale, a six-domain scale (material and physical well-being; relationships with other people; social, community, and civic activities; personal development and fulfillment; recreation; and independence), with a score range from 16 to 112 and with higher scores indicating greater quality of life (15); and the Modified Work and Social Adjustment Scale, an 11-point Likert scale that measures functional impairment in work, social life, and family life domains, with a score range from 0 to 50 and with higher scores indicating greater impairment (16). In addition, neurologists experts in movement disorders (A.J.E. and K.L.) rated FMD severity with the Psychogenic Movement Disorders Scale (PMDRS), which sums severity, duration factor, and incapacitation across body regions to produce a total score ranging from 0 to 144, with higher scores indicating greater FMD severity (17).
Statistical Analyses
In the descriptive analysis, categorical variables were reported using frequency and proportion and quantitative variables with means and standard deviations. A log-normality transformation was applied in nonnormally distributed variables. Spearman’s rank correlation coefficients were estimated between LOC-G and LOC-H scores separately for each study group. One-way analysis of variance was used to determine differences between all groups. In the adjusted analysis, a separate multivariable logistic regression was conducted to determine LOC differences between the FMD group versus the Parkinson’s disease group and the FMD group versus the focal dystonia group. The results of the logistic regression analysis were summarized by using relative risk ratios (odds ratios), 95% confidence intervals, and p values. Exploratory post hoc unadjusted LOC mean differences between the FMD group versus the Parkinson’s disease group and the FMD group versus the focal dystonia group were conducted with Bonferroni-corrected p values. Within the FMD group, adjusted associations of LOC variables with quality of life and functional impairment outcomes were determined by using ordinary least-squares analyses. The functional impairment, a latent variable standardized score, was created with work life, social life, and family life functional impairment scores by using a structural equation-modeling approach with a maximum likelihood estimation method. Ordinary least-squares analyses were summarized with relative regression coefficients, 95% confidence intervals, and p values. Within the FMD group, we determined the impact of LOC on PMDRS scores by using ordinary least-squares analyses. Variables at the 20% level of significance in the univariate analysis were considered for multivariable analyses. A backward automated-selection approach was used for selecting important covariates in the multivariable regression models. Variables with a 10% level of significance were retained in the final model. We performed sensitivity analyses to validate the stability of the regression models. All statistical analyses were conducted with Stata 15 (StataCorp, College Station, Tex.).
Results
A total of 156 patients (FMD, N=45, Parkinson’s disease, N=64, and focal dystonia, N=47) met inclusion criteria. The mean age of the study participants was 58.3 years (SD=14.2), and the mean duration of symptoms was 4.7 years (SD=1.1). Nine patients in the FMD cohort exhibited more than one FMD. The phenotypic range of FMDs included tremor (42.2%), dystonia (42.2%), chorea (13.3%), myoclonus (11.1%), tics (4.4%), and athetosis (4.4%). Patients in the FMD group were more likely to be younger and single and to have a shorter disease duration, fewer years of education, greater alexithymia and negative affect, lower quality of life scores, and higher functional impairment in work, social, and family life categories compared with patients in the Parkinson’s disease and focal dystonia groups (Table 1). Correlations between general and health-specific LOCs for all three study groups are summarized in Table S1 in the online supplement .
| Functional movement disorder (N=45) | Parkinson’s disease (N=64) | Focal dystonia (N=47) | |||||
|---|---|---|---|---|---|---|---|
| Characteristic | Mean | SD | Mean | SD | Mean | SD | pb |
| Age (years) | 47.5 | 13.5 | 66.0 | 8.2 | 58.1 | 14.7 | <0.001 |
| Age at onset (years) | 41.7 | 14.1 | 59.0 | 10.1 | 43.3 | 17.2 | <0.001 |
| Disease duration | 4.3 | 1.1 | 4.71 | 1.0 | 5.1 | 1.1 | 0.003 |
| Male (N, %) | 12 | 27.0 | 38 | 59.0 | 15 | 32.0 | <0.001 |
| Education (years) | 14.7 | 3.1 | 16.7 | 3.6 | 15.5 | 3.5 | 0.011 |
| Employed (N, %) | 9 | 20.0 | 28 | 44.0 | 21 | 45.0 | <0.001 |
| Married (N, %) | 22 | 49.0 | 55 | 86.0 | 30 | 64.0 | <0.001 |
| Internal LOC-G | 33.9 | 7.6 | 35.5 | 6.2 | 37.0 | 6.5 | 0.093 |
| External “chance” LOC-G | 14.7 | 7.8 | 16.8 | 7.9 | 12.9 | 8.6 | 0.042 |
| External “powerful others” LOC-G | 14.6 | 7.7 | 16.0 | 6.5 | 12.6 | 7.7 | 0.061 |
| Internal LOC-H | 21.5 | 6.3 | 19.1 | 5.5 | 16.1 | 5.9 | <0.001 |
| External “chance” LOC-H | 15.2 | 6.9 | 17.2 | 5.4 | 14.9 | 5.9 | 0.091 |
| External “doctors” LOC-H | 12.6 | 3.7 | 13.9 | 2.6 | 14.5 | 2.9 | 0.007 |
| External “other people” LOC-H | 8.7 | 3.7 | 8.5 | 3.1 | 8.0 | 3.4 | 0.630 |
| Alexithymia score | 58.6 | 10.3 | 55.9 | 9.1 | 53.2 | 8.1 | 0.021 |
| Alexithymia (N, %) | 18 | 40.0 | 20 | 31.0 | 8 | 17.0 | 0.050 |
| Positive affect | 32.6 | 9.7 | 31.9 | 8.2 | 34.3 | 7.2 | 0.340 |
| Negative affect | 22.5 | 9.3 | 18.3 | 5.8 | 16.5 | 5.5 | <0.001 |
| Quality of life | 74.7 | 20.2 | 83.4 | 10.9 | 86.0 | 12.2 | <0.001 |
| Functional impairment | |||||||
| Work life | 7.0 | 3.6 | 2.3 | 2.8 | 3.1 | 3.0 | <0.001 |
| Social life | 6.1 | 3.3 | 2.6 | 2.6 | 2.8 | 2.4 | <0.001 |
| Family life | 5.8 | 3.3 | 2.2 | 2.3 | 2.0 | 2.5 | <0.001 |
a
LOC=locus of control, LOC-G=Levenson Multidimensional LOC Inventory, LOC-H=Multidimensional Health LOC Assessment–Form C.
b
Values were generated with one-way analysis of variance.
General Frame of Reference
External (chance) LOC-G scores were significantly different between the FMD, Parkinson’s disease, and focal dystonia groups (Table 1). In the adjusted logistic regression analysis, patients with FMD had lower external (chance) LOC-G scores (odds ratio=0.90, 95% CI=0.83 to 0.99, p=0.031) compared with patients in the Parkinson’s disease group only (Figure 1A). Post hoc analysis showed no LOC-G unadjusted differences between the FMD and Parkinson’s disease groups or the FMD and focal dystonia groups (for further details, see Table S2 in the online supplement ).
FIGURE 1. Adjusted differences in locus of control for general and health-specific scores among the study participantsa
a The graphs show general (panel A) and health-specific (panel B) scores for the three study groups. Bars are shown with their corresponding standard deviation. Multivariable logistic regressions for FMD versus PD and FMD versus focal dystonia are also shown. FD=focal dystonia, FMD=functional movement disorder, PD=Parkinson’s disease.
*p<0.05.
Health-Specific Frame of Reference
Internal and external (doctors) LOC-H scores were significantly different between the three study groups (Table 1). In the adjusted logistic regression analysis, patients in the FMD group had higher internal LOC-H scores (odds ratio=1.22, 95% CI=1.05 to 1.42, p=0.008) and lower external (doctors) LOC-H scores (odds ratio=0.77, 95% CI=0.62 to 0.96, p=0.02) compared with patients in the focal dystonia group only (Figure 1B). Post hoc analysis showed significant unadjusted mean differences in internal LOC-H and external (doctors) LOC-H scores between patients with FMD and the focal dystonia group only (for further details, see Table S2 in the online supplement ).
Frame of Reference Modulation of Disease Severity, Quality of Life, and Functional Impairment in FMD Patients
The FMD disease severity score (PMDRS) was 19.5 (SD=10.7). LOC did not affect disease severity or quality of life. High external (powerful others) LOC-G scores (regression coefficient=−0.04, 95% CI=–0.08 to –0.004, p=0.029) were associated with low functional impairment.
Discussion
The novel application of examining LOC in patients with FMD revealed different internal versus external frames of reference when comparing these patients with control subjects with other neurological conditions (Parkinson’s disease and focal dystonia), with an unexpected (contrary to our hypothesis) high internal general and health-specific frame of reference among patients with FMD, which corresponds with a low external (doctor) health-specific frame of reference. These findings do not support the hypothesis of higher influence of perceived factors beyond one’s control (external) among patients with FMD, which may be implicitly assumed to be prevalent in this patient population. Also contrary to our hypothesis, the results suggest that the high internal frames of reference may not directly affect quality of life or disease severity.
As demonstrated in previous studies, greater internal LOC is associated with better understanding of one’s own disease process and self-care (18) and even predicts spell-free intervals among patients with PNES (19). In contrast to most patients with PNES (3), we found that FMD patients had a significantly higher internal health-specific LOC compared with control subjects with other neurological conditions. This may be explained by distinct age, disease duration, and psychiatric comorbidity in the samples. In addition, it has been proposed that LOC metrics may be useful for individualizing treatment strategies (11). It can be hypothesized that individuals with high internal LOC may benefit from self-directed therapies, whereas those with high external LOC may benefit from a predominantly caregiver-driven treatment. Our finding that patients in the FMD group had lower external (doctor) health-specific LOC compared with patients in the focal dystonia group may partially explain the historically poor prognosis and treatment response among FMD patients (20), most of whom are therapist-driven to seek treatment. However, it also provides a justification for self-guided treatment options, such as Internet-delivered cognitive-behavioral therapy (CBT) (21, 22). Nevertheless, prospective studies may identify FMD patients who may selectively respond to therapist-driven approaches (e.g., CBT).
FMD patients had the lowest quality of life scores but the highest impairment scores compared with patients in the Parkinson’s disease and focal dystonia groups. Previous studies have shown that disability and quality of life scores may be comparable between patients with FMD and those with Parkinson’s disease (23). Our FMD cohort, however, was more likely to be unemployed, which may explain these contrary findings. In addition, high external (powerful others) general LOC was associated with low functional impairment in FMD patients. This contradicts findings pertaining to other neurological conditions, such as Parkinson’s disease and multiple sclerosis, in which high scores for internal rather than external LOC have been associated with reduced functional impairment (1, 2).
Our study has some limitations that affect the strength of our conclusions. First, we did not screen for anxiety or depression, which are highly prevalent comorbid conditions among patients with FMD (23, 24). It is plausible that these psychiatric comorbidities may have an effect on quality of life, functional impairment, and severity metrics. Second, we did not include a healthy control group nor a functional control group in which the LOC might have a different influence. Third, we did not assess additional self-evaluations of core personality traits, such as generalized self-efficacy and self-esteem (25). These self-evaluations may modulate quality of life, functional impairment, and severity in FMD patients. Finally, the cross-sectional design precludes drawing any conclusions about the effect of personality estimates in prognosis or treatment response or any potential changes to LOC, even if it is considered to be generally stable across time.
Conclusions
The results of this study suggest that patients with FMD exhibit different internal versus external general and health-specific frame of reference compared with control subjects with other neurological conditions (Parkinson’s disease and focal dystonia). Contrary to our hypotheses, FMD patients had a high internal and low external (doctor) health-specific frame of reference compared with patients with focal dystonia. Although external (powerful others) general LOC modified functional impairment scores, LOC had no role in modulating disease severity or quality of life. Further work is needed to investigate associations between LOC profiles and the spectrum of predisposing and perpetuating vulnerabilities for FMD.
Supplementary Material
File (appi.neuropsych.18110290.ds001.pdf)
- View/Download
- 133.67 KB
References
1.
Gruber-Baldini AL, Ye J, Anderson KE, et al: Effects of optimism/pessimism and locus of control on disability and quality of life in Parkinson’s disease. Parkinsonism Relat Disord 2009; 15:665–669
2.
Bragazzi NL: The gap in the current research on the link between health locus of control and multiple sclerosis: lessons and insights from a systematic review. Mult Scler Int 2013; 2013:972471
3.
Strutt AM, Hill SW, Scott BM, et al: Motivation, psychopathology, locus of control, and quality of life in women with epileptic and nonepileptic seizures. Epilepsy Behav 2011; 22:279–284
4.
Hinson VK, Haren WB: Psychogenic movement disorders. Lancet Neurol 2006; 5:695–700
5.
Gelauff J, Stone J, Edwards M, et al: The prognosis of functional (psychogenic) motor symptoms: a systematic review. J Neurol Neurosurg Psychiatry 2014; 85:220–226
6.
Gupta A, Lang AE: Psychogenic movement disorders. Curr Opin Neurol 2009; 22:430–436
7.
Espay AJ, Lang AE: Phenotype-specific diagnosis of functional (psychogenic) movement disorders. Curr Neurol Neurosci Rep 2015; 15:32
8.
Gibb WR, Lees AJ: The relevance of the Lewy body to the pathogenesis of idiopathic Parkinson’s disease. J Neurol Neurosurg Psychiatry 1988; 51:745–752
9.
Fahn S, Bressman SB, Marsden CD: Classification of dystonia. Adv Neurol 1998; 78:1–10
10.
Levenson H: Multidimensional locus of control in psychiatric patients. J Consult Clin Psychol 1973; 41:397–404
11.
Wallston KA, Wallston BS, DeVellis R: Development of the Multidimensional Health Locus of Control (MHLC) scales. Health Educ Monogr 1978; 6:160–170
12.
Wallston KA, Stein MJ, Smith CA: Form C of the MHLC scales: a condition-specific measure of locus of control. J Pers Assess 1994; 63:534–553
13.
Bagby RM, Parker JDA, Taylor GJ: The twenty-item Toronto Alexithymia Scale–I: item selection and cross-validation of the factor structure. J Psychosom Res 1994; 38:23–32
14.
Watson D, Clark LA, Tellegen A: Development and validation of brief measures of positive and negative affect: the PANAS scales. J Pers Soc Psychol 1988; 54:1063–1070
15.
Burckhardt CS, Anderson KL: The Quality of Life Scale (QOLS): reliability, validity, and utilization. Health Qual Life Outcomes 2003; 1:60
16.
Mundt JC, Marks IM, Shear MK, et al: The Work and Social Adjustment Scale: a simple measure of impairment in functioning. Br J Psychiatry 2002; 180:461–464
17.
Hinson VK, Cubo E, Comella CL, et al: Rating scale for psychogenic movement disorders: scale development and clinimetric testing. Mov Disord 2005; 20:1592–1597
18.
Wassem R: A test of the relationship between health locus of control and the course of multiple sclerosis. Rehabil Nurs 1991; 16:189–193
19.
Duncan R, Anderson J, Cullen B, et al: Predictors of 6-month and 3-year outcomes after psychological intervention for psychogenic non epileptic seizures. Seizure 2016; 36:22–26
20.
Espay AJ, Aybek S, Carson A, et al: Current concepts in diagnosis and treatment of functional neurological disorders. JAMA Neurol 2018; 75:1132–1141
21.
Sharpe M, Walker J, Williams C, et al: Guided self-help for functional (psychogenic) symptoms: a randomized controlled efficacy trial. Neurology 2011; 77:564–572
22.
Newby JM, Smith J, Uppal S, et al: Internet-based cognitive behavioral therapy versus psychoeducation control for illness anxiety disorder and somatic symptom disorder: a randomized controlled trial. J Consult Clin Psychol 2018; 86:89–98
23.
Anderson KE, Gruber-Baldini AL, Vaughan CG, et al: Impact of psychogenic movement disorders versus Parkinson’s on disability, quality of life, and psychopathology. Mov Disord 2007; 22:2204–2209
24.
Carvalho HW, Andreoli SB, Lara DR, et al: The joint structure of major depression, anxiety disorders, and trait negative affect. Br J Psychiatry 2014; 36:285–292
25.
Kammeyer-Mueller JD, Judge TA, Scott BA: The role of core self-evaluations in the coping process. J Appl Psychol 2009; 94:177–195
Information & Authors
Information
Published In
History
Received: 26 November 2018
Revision received: 24 January 2019
Accepted: 6 March 2019
Published online: 30 September 2019
Published in print: Winter 2020
Keywords
Authors
Funding Information
Supported by NIH (grants 1R01HL125016-01, 1 R21 HL143030-01, 1R21 AI133207, and R21 AI118228 to Dr. Dwivedi) and by the Cancer Prevention and Research Institute of Texas (grants PP180003, PP170068, PP170004, PP140164, 140211, PP110156, PP150031, and PP130083 to Dr. Dwivedi).Dr. Dwivedi is a director of the Biostatistics and Epidemiology Consulting Lab at Texas Tech University Health Sciences Center, El Paso. Dr. LaFaver has served on the speaker’s bureau of Teva Pharmaceuticals; she has received compensation for contract research from Pfizer; and she has received speaker’s honoraria from the American Academy of Neurology and the Movement Disorders Society. Dr. Espay has served as a consultant to or on the scientific advisory board of Abbvie, Acadia, Acorda, Cynapsus/Sunovion, Impax, Lundbeck, Teva Pharmaceuticals, and USWorldMeds; he has received speaker’s honoraria from Abbvie, Acadia, the American Academy of Neurology, Lundbeck, the Movement Disorders Society, UCB, and USWorldMeds; and he has received royalties from Cambridge University Press, Springer, and Lippincott Williams and Wilkins. The other authors report no financial relationships with commercial interests.
Metrics & Citations
Metrics
Citations
Export Citations
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.
For more information or tips please see 'Downloading to a citation manager' in the Help menu.
View Options
View options
PDF/EPUB
View PDF/EPUBLogin options
Already a subscriber? Access your subscription through your login credentials or your institution for full access to this article.
Personal login Institutional Login Open Athens loginNot a subscriber?
PsychiatryOnline subscription options offer access to the DSM-5-TR® library, books, journals, CME, and patient resources. This all-in-one virtual library provides psychiatrists and mental health professionals with key resources for diagnosis, treatment, research, and professional development.
Need more help? PsychiatryOnline Customer Service may be reached by emailing [email protected] or by calling 800-368-5777 (in the U.S.) or 703-907-7322 (outside the U.S.).