Biobehavioral Intervention for Older Adults Coping With Essential Tremor

Transcription

1 Applied Psychophysiology and Biofeedback, Vol. 29, No. 1, March 2004 ( C 2004) Biobehavioral Intervention for Older Adults Coping With Essential Tremor Duane A. Lundervold 1,2,4 and Roger Poppen 3 Four questions were addressed: (a) does biobehavioral intervention result in within-session reduction of tremor severity; (b) do relaxation and electromyographic (EMG) biofeedback training produce differential effects; (c) do within-session treatment effects generalize to daily performance; and (d) are reductions in tremor severity maintained at follow-up assessment? Three adults, ages 51, 77, and 83, each with a diagnosis of essential tremor (ET), and a long standing history of tremor of the hands uncontrolled by medication, took part. A repeated pre post-training single-case experimental design embedded within a sequential A B C D design was used; in addition, 1 participant received a return to the B phase. Outcome measures included within-session clinical and self-ratings of tremor severity, surface electromyography (semg) of forearm muscles, and daily self-ratings of tremor at home. Tremor was measured while participants engaged in eating or drinking tasks. The Behavioral Relaxation Scale (BRS) served as a process measure to assess relaxation proficiency. Clinical ratings of tremor and the BRS had high interobserver agreement. Visual inspection and statistical tests of single-case data were used to evaluate outcomes. Each participant showed significant within-session improvements on various measures of tremor and improvement during intervention as compared to baseline phases. There were no clear-cut differences between relaxation and biofeedback phases. Improvements declined somewhat at a 12-week follow-up. Relationships among measures of tremor are discussed. Biobehavioral interventions hold promise for older adults coping with ET. Further research is needed using an array of biobehavioral measures to assess intervention outcome. KEY WORDS: essential tremor; relaxation; EMG biofeedback. Essential tremor (ET), the most prevalent idiopathic neurologic movement disorder, affects both young and old (Louis et al., 1995; Rautakorpi, Martilla, & Rinne, 1984). ET occurs in various areas of the body but the hands and head are the most frequently afflicted. Tremor is defined as an intermittent or continuous repetitive oscillation of a body part in one or more geometric planes resulting in rotational, vertical, or horizontal displacement of 1 Central Missouri State University, Warrensburg, Missouri. 2 Parkinson s Disease and Movement Disorders Center, Kansas University Medical Center, Kansas City, Kansas. 3 Southern Illinois University Carbondale, Carbondale, Illinois. 4 Address all correspondence to Duane A. Lundervold, Department of Psychology, 1111 Lovinger Hall, Central Missouri State University, Warrensburg, Missouri 64093; lundervold@cmsu1.cmsu.edu /04/ /0 C 2004 Plenum Publishing Corporation

2 64 Lundervold and Poppen the limb or appendage in space (Lundervold, 1997). Tremor can also be defined according to the context within which it occurs: while sitting (resting), during movement (kinetic), or holding a posture (postural). Tremor assessment consists of physiologic (accelerometry, electromyography [EMG]) and observational (clinical rating, self-rating) measures. Accelerometry typically evaluates movement in one dimension (Teravainen & Calne, 1980), though multidimensional or triaxial accelerometry has been recommended (Elble & Koller, 1990). To date, the sophisticated equipment needed for accelerometric assessment remains a basic research tool but has not been used clinically. EMG has a long history in the assessment of neuromuscular disorders and, through biofeedback procedures, can be used clinically to increase motor control (Basmajian, 1983). Surface electromyography (semg) can be used to measure activity of antagonist muscles that cause tremor in the afflicted area (Barcroft, Peterson, & Schwab, 1952; Chung, Poppen, & Lundervold, 1995; Delwaide & Gonce, 1988). Observational measures of tremor employ rating scales while the person engages in prescribed activities (Bain, 1993; Fahn, Elton, & Members of the UPDRS development Committee, 1988). Although the reliability of clinical rating is often questionable (Martinez-Marin & Bermejo-Pareja, 1988; Mayo, Sullivan, & Swaine, 1991), it is the most common measure in clinical research. Self-ratings of tremor have not been widely employed, although patients, with training, have shown good reliability (Montgomery & Reynolds, 1990). Tremor severity appears to be linearly related to disease duration (Elble, Higgins, & Hughes, 1992). Thus, persons most severely affected by ET are those who acquired the disorder early in life and are now older adults. Compared to the general population, persons with ET are significantly disabled in communication, work, emotional adjustment, home management, and leisure activities (Busenbark, J. Nash, S. Nash, Hubble, & Koller 1991; Metzer, 1992). Nearly 50% of the individuals with ET have disability when performing activities of daily living (ADL) involving the hands (Auff, Doppelbauer, & Fertl, 1991; Bain, 1993). Approximately 20% of the individuals with ET are forced to leave their jobs or change job responsibilities because of tremor-related disability (Metzer, 1992). Pharmacological treatment for ET is not entirely satisfactory, with positive response rates of only 40% and significant medication side effects (Findley, 1987; Koller, Busenbark, & Miner, and the Essential Tremor Study Group, 1994; Koller & Vetere-Overfield, 1989). Bain (1993) asserts that the magnitude of pharmacologic treatment effects for ET is an overestimate because of the use of measures (i.e., clinical ratings, spectral analysis, and accelerometry) with questionable validity and reliability. It is well known that ET is exacerbated by stress, fatigue, or conditions where vigilance is required (Jankovic, Kurland, & Young, 1989; Koller, 1984; Koller & Huber, 1989). The development of phobic-like behavior in some persons with ET has been reported (Lundervold, 1997; Wake, Takahashi, Onishi, Nadashima, & Yasumoto, 1974). These observations strongly suggest that ET is under biobehavioral control (Lundervold & Poppen, in press). In view of limitations regarding pharmacotherapy and the strong relationship between environmental stressors and tremor severity, investigation of biobehavioral (i.e., relaxation training and EMG biofeedback) intervention is warranted. In a series of uncontrolled case studies, Wake et al. (1974) reported that progressive muscle relaxation was helpful in reducing ET. Poppen, and colleagues (Chung, Poppen & Lundervold, 1995; Lundervold, Belwood, Craney, & Poppen, 1999) employed Behavioral Relaxation Training (BRT) to decrease tremor severity and disability. They found significant

3 Biobehavioral Intervention for Older Adults Coping With Essential Tremor 65 reductions in clinical and self-ratings of tremor severity. Chung et al. and Lundervold each reported decreased forearm EMG levels. A 47 66% reduction in tremor severity was reported by Lundervold et al. This study represents a systematic replication of Chung et al. and an extension of previous research in several ways. First, all participants had confirmed medical diagnoses of ET. Second, assessment of tremor severity took place during performance of meaningful behaviors such as eating. Third, dynamic semg training was provided during performance of ADL. Fourth, follow-up assessment was of 12 weeks postintervention. Finally, reliability of observation of relaxed behaviors and tremor severity was obtained. Four questions were addressed: (a) does biobehavioral treatment result in withinsession reductions of tremor severity; (b) do relaxation and electromyographic (semg) biofeedback produce differential effects; (c) do within-session treatment effects generalize to daily performance; and (d) are reductions in tremor severity maintained at follow-up assessment? METHOD Participants Participants were three cognitively intact older adults with tremor of the hands and diagnosed with ET by a neurologist (see Table I). Participants were recruited from physician offices and social/civic groups. Measures Clinical Ratings Clinical ratings of tremor severity (CRTS) were made from videotapes of performance of standard maneuvers and ADLs (drinking and eating) using a 0(no tremor) to 9(extreme Table I. Description of Participants Severity a Duration Subject Age Gender Tremor type Right Left (years) GDS b MSQ c Medication d ED 51 M Kinetic None Postural 0 2 Resting 0 0 TH 77 F Kinetic None Postural 7 7 Resting 9 0 MA 81 F Kinetic Inderal Postural mg Resting 0 0 a Severity based on 9-point rating scale (Bain et al., 1993; Fahn et al., 1988; see text). b Geriatric Depression Scale (Yesavage, 1986); scores less than 11 indicate no depression. c Performance on the Short Portable Mental Staus Examination (Kahn, Goldfarb, Pollack, & Peck, 1960); scores of 7 or above indicate no cognitive impairment. d Stabilized on medication for 2 months prior to entering the study.

4 66 Lundervold and Poppen tremor) point scale (Bain, 1993). ADLs were performed for approximately 2 min and a rating given for each performance period. Raters were trained to use the scale with high levels of agreement and the primary raters were blind to the phases of the study. Videotape recordings of baseline posttraining and the last four (posttraining) observations during intervention phases, during which ADL performance was assessed, were made. Self-Ratings Self-ratings of tremor severity (SRTS) were given by the participant in each session immediately after completing the ADL(s) using a 0- to 9-point scale analogous to the clinical rating scale (Montgomery & Reynolds, 1991). They also used this scale to make a daily home rating of tremor during eating or drinking. One participant s spouse independently rated his daily tremor. EMG Muscle activity data were collected and analyzed by a BIOCOMP 2001 program interfaced with an IBM-compatible computer. Bandpass frequency was set at Hz, sampling frequency was 20 Hz, raw semg signals were converted using the Root-Mean- Square method, and mean semg levels (in microvolts, µv) were calculated in consecutive 15-s intervals. These 15-s means were averaged for the duration of the standard maneuvers and ADL tasks. At the start of each session, the skin over the relevant musculature first was lightly abraded with alcohol swabs followed by additional cleansing using EMG preparation spray. Surface electrodes, 11-mm disposable pregelled silver/silver chloride sensors, were attached to the skin with adhesive disks. Active sensors, with a center-to-center distance of approximately 7 cm, were placed on the forearm flexor carpi radialis and the forearm extensor carpi radialis, with the reference placed directly over the humeral epicondyle (Poppen & Maurer, 1982). Both right and left forearms were assessed for ED and TH, but only the right forearm of MA. During biofeedback training, pairs of active electrodes were also placed over the biceps and medial deltoid of MA s right arm. Independent Variables Behavioral Relaxation Training (BRT) BRT consisted of teaching 10 behaviors using instruction, modeling, and performance feedback (Poppen, 1998). Relaxation in both reclined and upright seated positions was taught in separate phases with each session lasting about 20 min. The Behavioral Relaxation Scale (BRS) was used as a direct measure of performance. A 5-min observation period was used to assess proficiency (Poppen, 1998) and provided a process measure of training. EMG Biofeedback Training Audio EMG biofeedback was provided by the BIOCOMP for changes in muscle tension in the relevant muscles during performance of ADLs.

5 Biobehavioral Intervention for Older Adults Coping With Essential Tremor 67 Procedure Participants engaged in at least four phases of intervention in the same order: (A) Baseline, (B) Reclined BRT, (C) Upright BRT, and (D) EMG Biofeedback. One participant (MA) experienced a return to the B phase. In addition, all received an initial screening session and a follow-up session 12 weeks after their last intervention. Screening Interview Consent was obtained and demographic and screening data were collected. Tremor was assessed using the standard procedure (Fahn et al., 1988) to examine the severity of bilateral kinetic, postural, and resting tremor. Videotapes of the maneuvers were made and then rated using the criteria of Bain (1993). Finally, participants were trained to use the SRTS scale and instructed to make daily home ratings. (A) Baseline: During the first baseline session, participants were given a 5-min adaptation period to the physiologic equipment. Pretraining assessment was conducted with participants seated in an upright chair and asked to relax and perform the target ADL task for 2 min. ED performed the drinking and eating tasks with right and left hands; TH performed the eating task with right and left hands; MA performed the drinking task with her right hand. EMG was recorded during the ADL performance and SRTS scores were obtained at the end of ADL task. Participants next were asked to relax first in a fully reclined position of a reclining chair then in an upright position in a straight back chair. A 5-min BRS observation was conducted in each position. Participants then were asked to perform the ADLs again. Posttraining EMG and SRTS were recorded and ADL performance videotaped for later CRTS scoring. The criterion for phase change was three consecutive Rec-BRS scores that varied by not more than 10%. (B) Reclined Relaxation Training (Rec-BRT): Reclined BRT was conducted for approximately 20 min each session. Pre- and posttraining assessments were conducted as in baseline. Participants were encouraged to practice BRT at home for at least 20 min once a day and to apply BRT during ADLs. The phase change criterion was three consecutive posttraining Rec-BRS scores of at least 80% relaxed. (C) Upright Relaxation Training (Up-BRT): Participants were trained to relax in a straight back chair for approximately 20 min each session. Pre- and posttraining assessments were conducted as in previous phases and instructions for home practice was the same as the previous phase. The criterion for phase change was three consecutive sessions with Up-BRS scores of at least 80% relaxed. (D) EMG Biofeedback Training (Biofeedback): EMG biofeedback training was provided while participants performed an ADL. Audio signals proportional to muscle tension levels were provided while the participant engaged in the activity for minutes. ED and TH were trained to reduce tension in the right forearm extensor while drinking and eating, respectively. In an effort to reduce tremor by changing the biomechanics of upper arm activity, MA was trained to increase tension in her right biceps while drinking. Pre- and posttraining assessments, with no feedback, were conducted as in previous phases. This phase was ended when performance

6 68 Lundervold and Poppen appeared to plateau for ED and TH, and when MA showed a generalized increase in EMG levels. Follow-Up A single follow-up session, 12 weeks after the last intervention, was conducted in a manner identical to baseline sessions. Reliability CRTS reliability was calculated on the basis of two independent raters simultaneously rating performance on approximately 25% of the videotape recordings. Reliability was calculated as percent agreement (agreements/[agreements + disagreements] 100). Agreement was defined as ratings falling within the same severity category (Bain et al., 1993). Reliability for CRTS scores ranged from 75 to 88%. Reliability for BRS scores, obtained from approximately 25% of the sessions, ranged from 81 to 94%. Experimental Design and Analysis of Results A repeated pre posttraining single-case experimental design, embedded within a sequential A B C D design, was used (Curtis & Thyer, 1983). In the context of group research, the pre post treatment design provides a high degree of internal validity. Similarly, when applied to a single case, internal validity of this design is also high because the time interval between pre- and posttraining assessments is brief and the only event occurring between the two measurement periods is manipulation of the independent variable. Inferential statistical tests were used to determine the magnitude and reliability of changes in the measures for each participant across phases of the study (Crosbie, 1999). Inferential statistical tests rely on the assumption that the residuals of scores (differences between the mean and raw scores) are independent (Belwood, 1997; Huitma, 1995). Serial dependence of residuals may be determined by a lag-1 autocorrelation (ACF[1]); if ACF[1] is not significant inferential statistical analyses may be performed (Belwood, 1997; Huitema, 1985). Accordingly, for each measure the residuals of data collected during the baseline phase were tested for ACF[1]. The Bonferroni correction procedure was used to control for inflation of chance significance. The range of corrected alpha level was RESULTS Data were analyzed for each participant with results from one representative case (ED) presented. (All tables and figures are available from the first author.) Statistical analyses (ANOVA) were performed when ACF[1] for residuals in baseline data were not significant. Because only a single follow-up session was conducted, statistical analysis was not conducted, allowing only visual inspection. ED received four baseline, eight reclined, and then six Up-BRT sessions. Ten biofeedback sessions were then given. ED s tremor was assessed pre- and posttraining, on both the drinking and eating tasks, for right and left hands. Extensor EMG was consistently much

7 Biobehavioral Intervention for Older Adults Coping With Essential Tremor 69 Table II. Analysis of Variance Summary Table for ED ACF[1] Dependent variable DW a r p Factor F df p Extensor EMG drinking (no further analyses) Flexor EMG drinking Phase Pre Post Left Right Extensor EMG eating (no further analyses) Flexor EMG eating Phase Pre Post Left Right Self-rating drinking Phase Pre Post Left Right Self-rating eating Phase Pre Post Left Right Pre Post Left (ns) b Right interaction Clinical rating Phase (drinking and eating) ADL (ns) Laterality (ns) Home ratings (no further analyses) a DW: Durbin Watson test. b NS: nonsignificant. greater than flexor EMG. ANOVA of flexor EMG during drinking revealed significant main effects of phase, pre post testing and left right differences (see Table II). Post hoc tests indicated that flexor EMG was significantly lower during the treatment phases as compared to Baseline, but there were no differences among the treatment phases. posttraining flexor EMG was significantly lower than pretraining measures, indicating within-session treatment effects. The significant left right main effect showed that flexor EMG was consistently lower in ED s right arm compared with his left arm during drinking. ANOVA of flexor EMG during eating indicated significant main effects of phase, pre post-training, and left right differences. A significant main effect of phase, with subsequent post hoc tests, showed flexor EMG was lower during Biofeedback as compared to Baseline. Flexor EMG was lower during posttraining assessment and lower in the right arm. ANOVAs of SRTS data for eating and drinking are given in Table II. A significant main effect of phase indicated that SRTS was lowest during Biofeedback. posttraining ratings also were lower than pretraining indicating a within-session treatment effect. SRTS for ED s left hand was lower than for his right. SRTS scores during eating are very similar to those obtained during drinking: (a) ratings were lower during treatment than baseline, with no differences between treatments; (b) a within-session effect was obtained; and, (c) SRTS was lower for the left hand. A significant Pre Post Left Right interaction showed greater pre post reductions occurred with the right as compared to the left hand. CRTS for drinking and eating were analyzed together in a three-factor ANOVA (see Table II). A main effect of phase was obtained with a significant decrease in CRTS scores during treatment phases compared to baseline; however, no differences between interventions emerged. No other main effects or interactions were found.

8 70 Lundervold and Poppen ED made daily ratings for tremor during drinking and eating, whereas his spouse independently rated his tremor. Visual inspection indicated ED s home ratings appeared improved during Up-BRT, showed further improvement during Biofeedback, and were maintained at follow-up. His spouse s ratings showed a similar pattern. Significant ACF[1] precluded further statistical analyses of these data (see Table II). Correlation analysis of measures of tremor during the drinking and eating ADLs for right and left hands was conducted. Two process measures of relaxation proficiency, Rec- BRS and Up-BRS, were correlated with tremor measures (Rec-BRS and CRTS: r =.68 to.85, p = ; Up-BRS and CRTS: r =.58, p =.01). BRS scores generally were negatively associated with semg and ratings, showing that greater relaxation during the training period was related to decreased muscle tension and observed tremor. semg and clinical and self-ratings were associated about 75% of the time. Flexor and extensor semg also were significantly related (Ext EMG and Flx EMG: r =.50.63, p = ; Ext EMG-SRTS: r =.57.59, p = ; Flx EMG and SRTS: r =.47, p =.01; Flx EMG and Up-BRT: r =.53, p =.01). Clinical and self-ratings also were moderately correlated (SRTS and CRTS: r =.69, p =.003). At follow-up, all EMG measures were maintained at the levels of the last intervention phase. SRTS scores increased slightly above those in the intervention phases but did not return to baseline levels. Clinical ratings found very little tremor. ED s home ratings of tremor, and those of his spouse, increased slightly at follow-up but remained well below baseline. DISCUSSION Four questions were raised at the outset of this study. The first, concerning withinsession effects of biobehavioral training, was answered affirmatively by the significant reductions in tremor from pre- to posttraining assessments. All three participants reported decreased tremor in the posttraining ADL as compared to pretraining. Pre post reductions in EMG levels were also found for two participants. These results extend the earlier findings of Chung et al. (1995) by demonstrating that biobehavioral training has an immediate impact on tremor occurring during ADL tasks. The second question concerned differential treatment effects and was addressed by examining differences between phases. The interventions were regarded not as separate, independent treatments but as a cumulative sequence. Rec-BRT was taught first because learning relaxation skills is likely to be easier with full body support (Poppen, 1998). Upr-BRT came next, as a means of translating relaxation to a posture allowing everyday activities. Finally, biofeedback was seen as adding a greater degree of motor control to that achieved by relaxation. Thus, improvements were expected in each successive phase. Overall, there were consistent significant improvements in self-ratings, clinical ratings, and many EMG measures, in the treatment phases over baseline. Progressive differences between intervention phases were less consistent. Significant sequential decreases were obtained by ED in SRTS scores for drinking and flexor EMG for eating. Flexor EMG progressively declined for TH. For MA, EMG decreased during the relaxation phases and increased during Biofeedback. Home ratings of tremor severity appeared to decline in a sequential fashion across phases, though statistical analysis could confirm this pattern

9 Biobehavioral Intervention for Older Adults Coping With Essential Tremor 71 only for MA. Whether biofeedback adds to the effectiveness of BRT was not conclusively answered in this study. The third research question addressed generalization of treatment effects to daily performance. All three participants reported significantly decreased tremor in their daily eating or drinking activities. Generalization likely was mediated by their practicing relaxation skills at home. Relaxation, or the motor control learned in biofeedback, is an active skill that must be employed continually in order to serve as an adaptive alternative to problematic behavior (Poppen, 1998). The fourth question concerned maintenance of treatment gains. Some increases in tremor measures at follow-up, compared to intervention phases, were apparent but were not evaluated statistically. Clinical and self-ratings of tremor severity showed slight or no increases and were well below baseline levels. EMG levels appeared to remain low for ED, increased for TH, and remained at high levels for MA. Like generalization, maintenance may be related to home practice. MA reported regular practice during the follow-up period, ED reported intermittent practice, and TH reported that she discontinued relaxation practice. The role of home practice in the generalization and maintenance of self-regulation skills is a matter that requires more rigorous assessment and evaluation in future research. This study also permitted the comparison of various measures of tremor. Consistent correlations were found between self- and clinical ratings of tremor severity. This confirms the findings of Montgomery and Reynolds (1991) with PD patients, that individuals can be trained to be reliable judges of their own tremor. It should be noted that clinical ratings were made at a later date of videotaped performance and that the raters were blind to the participants self-ratings. Bain s assertion (1993) that the sweep speed of videotape and cycles per second of tremor interact to wash out the observability of tremor on video is a matter of concern. If so, CRTS scores in this study are underestimates. Comparisons of direct observation and video ratings are needed to address this issue. Positive correlations between flexor and extensor EMG generally were significant for ED, but not for TH or MA. This finding provides only weak support for the idea that co-contraction of antagonist muscles contributes to tremor (Barcroft et al., 1952). Correlations between EMG levels (flexor or extensor) and ratings of tremor (self or clinical) were significant in one fourth of the comparisons for each participant, suggesting that these two classes of measures were largely independent. In contrast, Chung et al. (1995) found a high degree of correspondence between tremor ratings and EMG measures, using a placement that combined both flexor and extensors. These results suggest that research is needed to determine electrode placement that is most sensitive to tremor in each individual. The relationship between EMG and tremor rating was complicated by the findings with MA. Clinical observation suggested that her tremor was exacerbated by abduction of her upper arm as she engaged in the drinking activity. Thus, in the Biofeedback phase, the biomechanics of this action was altered by increasing biceps tension. This was successful in reducing tremor severity ratings but had the effect of increasing forearm EMG levels as well. Forearm tension remained high, even when she was given further Rec-BRT, but tremor ratings remained low. It may be possible, at least in some cases, to alleviate tremor by postural adjustments even if it produces increased activity in certain muscles. These results confirm that there is no simple relationship between EMG and other measures of tremor (Elble & Koller, 1990). Use of additional biobehavioral measures related to tremor, for example, electrodermal activity, heart rate, and displacement during dynamic movement,

10 72 Lundervold and Poppen and their relationship to treatment process and outcome, needs to be evaluated (Lundervold, 1997; Lundervold et al., 1999). Finally, it was observed that the process measure of relaxation proficiency (BRS) was strongly negatively associated with both EMG and rating measures, particularly for ED and MA, who reached the relaxation training criteria. That is, the greater the degree of relaxation during training, the lower the tremor during assessment. This finding adds to the internal validity of the study. Elble and Koller (1990), in their seminal text on tremor, provided a dire assessment of the value of behavioral interventions. Our results indicate that their conclusion regarding the futility of biobehavioral intervention for ET is premature. Relaxation and dynamic EMG biofeedback training hold promise for older adults coping with tremor and related disability. ACKNOWLEDGMENTS A Doctoral Dissertation Research Award from Southern Illinois University Carbondale provided partial support for the project. The assistance of Marilyn Belwood, James L. Craney, and Todd Streff is appreciated. The comments of three anonymous reviewers were invaluable. REFERENCES Auff, E., Doppelbauer, A., & Fertl, E. (1991). Essential tremor: Functional disability vs. subjective impairment. Journal of Neural Transmission, 33(Suppl.), Bain, P. (1993). A combined clinical and neurophysiological approach to the study of patients with essential tremor. Journal of Neurology, Neurosurgery, and Psychiatry, 56, Barcroft, H., Peterson, E., & Schwab, R. S. (1952). Action of adrenaline and noradrenaline on the tremor of Parkinson s disease. Neurology, 2, Basmajian, J. V. (1983). Biofeedback: Principles and practice for clinicians (2nd ed., pp ). Baltimore: Williams & Wilkins. Belwood, M. F. (1997). A Monte Carlo study of the relationship between linear model specification and estimates of lag-one autocorrelation in data from a single-case (N = 1) design. Doctoral dissertation, Southern Illinois University Carbondale. Busenbark, K. L., Nash, J., Nash, S., Hubble, J. P., & Koller, W. C. (1991). Is essential tremor benign? Neurology, 41, Chung, W., Poppen, R., & Lundervold, D. A. (1995). Behavioral relaxation training for older adults with tremor disorders. Biofeedback and Self-Regulation, 20, Crosbie, J. (1999). Statistical inference in behavior analysis: Useful friend. Journal of Applied Behavior Analysis, 22, Curtis, G. C., & Thyer, B. A. (1983). The repeated pretest post-test single subject experiment: A new design for empirical practice. Journal of Behavior Therapy and Experimental Psychiatry, 14, Delwaide, P. J., & Gonce, M. (1988). Pathophysiology of Parkinson s signs. In J. Jankovic & E. Tolosa (Eds.), Parkinson s disease and movement disorders (pp ). Baltimore & Munich: Urban & Schwarzenberg. Elble, R. J., & Koller, W.C. (1990). Tremor. Baltimore: Johns Hopkins University. Elble, R. J., Higgins, C., & Hughes, L. (1992). Longitudinal study of essential tremor. Neurology, 42, Fahn, S., Elton, R. L., & Members of the UPDRS development committee. (1988). Unified Parkinson s disease rating scale. In S. Fahn, C. D. Marsden, M. Goldstein, & D. B. Calne (Eds.), Recent developments in Parkinson s disease (pp ). New York: MacMillan. Findley, L. J. (1987). The pharmacology of essential tremor. In C. D. Marsden & S. Fahn (Eds.), Movement disorders (2nd ed., pp ). London: Butterworth. Huitema, B. E. (1985). Autocorrelation in applied behavior analysis: A myth. Behavioral Assessment, 7, Jankovic, J., Kurland, R. M., & Young, R. R. (1989, November 15). Managing the patient with tremor. Patient Care, pp Kahn, R. L., Goldfarb, A., Pollack, M., & Peck, A. (1960). Brief objective measures for the determination of mental status in the aged. American Journal of Psychiatry, 117,

11 Biobehavioral Intervention for Older Adults Coping With Essential Tremor 73 Koller, W. C. (1984). Diagnosis and treatment of tremors. Neurologic Clinics, 2, Koller, W. C., Busenbark, K., Miner, K., & the Essential Tremor Study Group. (1994). The relationship of essential tremor to other movement disorders: Report on 678 patients. Annals of Neurology, 35, Koller, W. C., & Huber, S. J. (1989). Tremor disorders of aging: Diagnosis and management. Geriatrics, 44, Koller, W. C., & Vetere-Overfield, B. (1989). Acute and chronic effects of propranolol and primidone in essential tremor. Neurology, 39, Louis, E. D., Marder, K., cote, L., Pullman, S., Ford, B., Wilder, D., et al. (1995). Differences in the prevalences of essential tremor among elderly African-Ameicans, whites, and Hispanics in northern Manhattan, NY. Archives of Neurology, 52, Lundervold, D. A. (1997). Behavioral medicine intervention for older adults coping with essential tremor and related disability. Directions in Rehabilitation Counseling, 3, Lundervold, D. A., Belwood, M. F., Craney, J. L., & Poppen, R. (1999). Reduction of tremor severity and disability following Behavioral Relaxation Training. Journal of Behavior Therapy and Experimental Psychiatry, 30, Lundervold, D. A., & Poppen, R. (in press). Essential tremor and disability: The role of biobehavioral conditioning. Clinical Gerontologist. Martinez-Marin, P., & Bermejo-Pareja, F. (1988). Rating scales in Parkinson s disease. In J. Jankovic & E. Tolosa (Eds.), Parkinson s disease and movement disorders (pp ). Baltimore & Munich: Urban & Schwarzenberg. Mayo, N. E., Sullivan, J., & Swaine, B. (1991). Observer variation in assessing neurological signs among patients with head injuries. American Journal of Physical Medicine and Rehabilitation, 70, Metzer, W. S. (1992). Severe essential tremor compared with Parkinson s disease in male veterans: Diagnostic characteristics, treatment and psychosocial implications. Southern Medical Journal, 85, Montgomery, G. K., & Reynolds, N. C. (1990). Compliance, reliability, and validity of self-monitoring for physical disturbances of Parkinson s disease. Journal of Nervous and Mental Disease, 178, Poppen, R. (1998). Behavioral relaxation training and assessment (2nd ed.). Thousand Oaks, CA: Sage. Poppen, R., & Maurer, J. (1982). Electromyographic analysis of relaxed postures. Biofeedback and Self-Regulation, 7, Rautakorpi, I., Martilla, R. J., & Rinne, U. K. (1984). Epidemiology of essential tremor. In L. J. Findley & R. Capildeo (Eds.), Movement disorders: Tremor (pp ). London: MacMillan. Teravainen, H., & Calne, D. (1980). Quantitative assessment of Parkinson s deficits. In U. K. Rinne, M. Linger, & G. Stamm (Eds.), Parkinson s disease: Current problems, progress, and management (pp ). Baltimore: Elsevier. Wake, A., Takahashi, Y., Onishi, T., Nadashima, T., & Yasumoto, I. (1974). Treatment of essential tremor by behavior therapy Use of Jacobson s progressive relaxation method. Journal of Psychiatry and Neurology in Japan, 76, Yesavage, J. A. (1986). The use of self-rating depression scales in the elderly. In L. W. Poon (Ed.), Clinical memory assessment (pp ). Washington, DC: American Psychological Association.

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