Differentiating Psychological Characteristics of Patients with Sleep Apnea and Narcolepsy

Transcription

1 Sleep, 4(1): Raven Press, New York : Differentiating Psychological Characteristics of Patients with Sleep Apnea and Narcolepsy *Larry E. Beutler, tj. Catesby Ware, tismet Karacan, and tjohn 1. Thornby *University of Arizona College of Medicine, Tucson, Arizona; tsleep Disorders Center, Department of Psychiatry, Baylor College of Medicine, and Sleep Laboratory, Veterans Administration Hospital, Houston, Texas Summary: Fifty male subjects were group-matched for age and socioeconomic status. Twenty of the subjects were diagnosed as having sleep apnea and 20 were diagnosed as having narcolepsy on the basis of sleep studies. The remaining 10 subjects served as normal controls. Differences among the groups were evaluated on the bases of two psychological instruments designed to assess personality characteristics and mood states. The findings suggest that narcoleptics and apneics both present discriminatively different psychological profiles than do normals. Moreover, personality characteristics of these two groups are distinguishable from one another. Apneics tend to be individuals with hypochondriacal and hysterical characteristics, whereas narcoleptics are more easily characterized by anxiety and social introversion. Both severity of psychological disturbance (mean Minnesota' Multiphasic Personality Inventory elevations) and personality pattern (two-point codes) distinguish the groups. Key Words: Sleep apnea-n arcolepsy Psychological profiles. There have been few investigations of the personality characteristics associated with those sleep disorders which apparently have an organic etiology. In contrast, functional sleep disturbances such as initial insomnia have frequently been attributed to the personality characteristics and coping styles of the sufferers (e.g., Monroe, 1967; Kales et ai., 1976). This lack of data is becoming increasingly apparent as more and more research suggests that life stress, psychological coping styles, and other characteristics of personality may strongly influence the onset and course of a wide variety of clearly organic diseases (e,g., Holmes and Rahe, 1967; Kimball, 1972; Roessler, 1976). Current conceptualizations of the relationship betwen psychological and somatic variables suggest that any physical disease Accepted for publication November Address correspondence and reprint requests to Dr. Beutler at Department of Psychiatry, Arizona Health Sciences Center, Tucson, Arizona

2 40 L. E. BEUTLER ET AL. process represents the final common pathway of a number of influences, including sociocultural ones and those related to a patient's ability to cope with stress. The limited survey and clinical information that is available suggests that there may be certain personality characteristics associated with physiological sleep disorders. For example, Broughton and Ghanem (1976) observe that narcoleptics may have difficulties with issues of autonomy and the establishment of independence. They observed that narcoleptics are prone to mood changes, depressive episodes, and are generally worrisome individuals. Sleep apnea patients, the other large patient group that commonly presents with excessive daytime sleepiness, often manifest irritability, anxiety, poor concentration, and symptoms of depression (Okada et ai., 1977; Guilleminault et ai., 1978; Neil et ai., 1978). These findings suggest that there may be psychological manifestations which are peculiar and particular to the conditions of narcolepsy and sleep apnea. This paper represents an effort to investigate the personality and mood characteristics of these patients. METHOD Subjects Fifty male subjects comprised the sample for this study. Twenty of these males were diagnosed as having obstructive sleep apnea on the basis of complaints and diagnostic sleep studies. Final diagnosis was based on 3 nights oflaboratory study in which electroencephalogram - electro-oculogram (EEG - EOG) monitoring was performed along with measurements of nasal-oral respiration, oxygen saturation, esophageal pressure, and heart rate. All apnea patients satisfied the minimum diagnostic criteria of 50 apnea episodes of at least 10 sec duration during each night of the evaluation. An additional 20 subjects were diagnosed as having narcolepsy on the basis of clinical history and diagnostic sleep studies. The final diagnosis of this group was based on a minimum of 3 nights of laboratory study during which EEG-EOG, respiration, and heart rate variables were recorded. Both rapid eye movement sleep latency of less than 15 min for at least 1 night and two symptoms from the classical narcoleptic tetrad were required for a final diagnostic classification. In the latter part of the study, diagnoses were also confirmed with multiple sleep latency tests (Richardson et ai., 1978) and measures of regional cerebral blood flow (Sakai et ai., 1979). These studies were performed after withdrawal of all current medications. The control group consisted of 10 individuals who presented no sleep disorder, medical complaint, or symptoms. These subjects were recruited through advertisements and had no sleep complaint or known medical condition. They were studied through a similar three-session series of laboratory nights, during which EEG-EOG recordings, respiratory function, and other measurements were obtained. Control subjects were retained for study only if these findings were within normal limits. Subjects in all three groups were given a general physical and psychiatric examination. Those with primary medical or psychiatric disorders were ruled out Sleep, Vol. 4, No. I, 1981

3 DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS 41 for further study. Patients were recruited through advertisements in newspapers or were referred by their physicians. All subjects were selected in order to insure a group match on the basis of education and age. Consecutively admitted patients and volunteers who met the requisite criteria for one of the groups were selected for study. Ages and socioeconomic status of the three groups were not significantly different. Mean ages were 45.6 years (SD = 6.8) in the apnea group, 42.3 years (SD = 11.2) in the narcolepsy group, and 41.7 years (SD = 7.7) in the control group. Mean educational levels in the three groups were 14.3, 14.0, and years, respectively. Procedure All subjects were admitted to the Baylor College of Medicine Sleep Disorders and Research Center and were administered psychological tests in a routine fashion. Standard polysomnographic procedures were used in wiring, recording, and scoring of sleep data (Williams et ai., 1974). The psychological measures consisted of the Minnesota Multiphasic Personality Inventory (MMPI) and the Profile of Mood States (POMS). The MMPI was scored on both the validity and the 10 clinical scales. Scores on this test were assumed to reflect relatively stable personality characteristics and predispositions. In contrast, the POMS was assumed to evaluate a patient's transitory moods and general affects. This latter test evaluates six areas of state-related mood functioning; tension, depression, anger, vigor, fatigue, and confusion. One-way analyses of variance with a two-tailed alpha criteria were initially used to compare the three groups on each of the 13 MMPI scales and 6 POMS scales. When any of these was significant, we then compared the groups two-at-a-time using the Scheffe multiple comparison procedure (Scheffe, 1959) in order to establish the source of the differences. A stepwise discriminant analysis (Dixon, 1979) was also performed to determine the combination of scales from the MMPI and POMS that optimally distinguished among the three groups. In addition, the high-point codes (i.e., peak scores independent of actual elevation) from the MMPI were extracted for each subject and a tabulation was made of the frequency with which each of the MMPI scales fell within this high-point-code profile for each group. The two most frequent scales for each group were extracted and formed the basis for developing a two-point rule for distinguishing among the three groups. Each subject was scored as having the particular profile if either one or both of the two characteristics were reflected in the subject's highest two scores. The three MMPI profiles (one for each group) were then separately analyzed in all pairwise comparisons between the three groups in a series of 2 x 2 X2 analyses (i.e., each combination of groups was separately compared on each code type). It should be noted that unlike the other analyses, this analysis reflected differences in pattern rather than symptom intensity. RESULTS All relevant statistical comparisons relied on two-tailed tests of significance. Sleep, Vol. 4, No.1, 1981

4 42 L. E. BEUTLER ET AL. Individual Scale Comparisons Mean values for the three groups of subjects on the individual MMPI and POMS scales are illustrated in Table 1. Differences among means are illustrated in Figs. 1 and 2. Narcoleptics were distinguished from controls as being relatively more depressed, anxious, and fatigued and as having less vigor. Apneic patients were distinguished from controls as being relatively more hypochondriacal (Hs) and depressed, and as being less vigorous. When comparing the two patient groups, we found that narcoleptics were relatively more socially introverted and confused than apneics, whereas apneics expressed relatively greater denial than narcoleptics. When considering the combined patient groups in comparison to the controls, it is apparent that the best individual discriminators are vigor, depression, hypochondriasis, fatigue, and psychasthenia. All these scales indicate values in the direction of impairment for the patient groups. Discriminant Analysis A multiple discriminant analysis was performed and was designed to determine which of the POMS and MMPI scales best distinguished among the three groups. TABLE 1. Means and standard deviations of personality scales Scales Control Narcoleptic Apneic MMPI Hs (4.37) (10.06) (10.21) D (7.24) (12.47) (10.72) Hy (4.64) (8.60) (10.36) Pd (10.52) (7.54) (11.87) Mf (6.81) (11.00) (9.58) Pa (8.30) (9.19) (8.60) Pt (7.44) (11.84) (11.07) Sc (9.65) (10.45) (9.50) Ma (10.62) (9.94) (9.37) Si (9.58) (10.49) (8.69) L (3.83) (5.49) (7.43) F (4.52) (6.98) (4.33) K (7.36) (9.41) (7.67) POMS T 6.70 (3.88) 9.45 (6.37) 7.90 (7.14) D 4.70 (5.27) 9.60 (11.70) 4.85 (8.80) A 4.90 (4.12) 7.25 (7.45) 4.75 (7.19) V (4.29) (5.56) (4.75) F 3.50 (3.80) (6.12) 8.00 (5.25) C 3.70 (2.86) 7.65 (5.36) 4.15 (3.59) Abbreviations used in the scales: Minnesota Multiphasic Personality Index (MMPI): Hs, hypochondriasis; D, depression; Hy, hysteria; Pd, psychopathic deviant; Mf, masculinity-femininity; Pa, paranoia; Pt, psychasthenia; Sc, schizophrenia; Ma, hypomania; Si, social introversion; L, F, and K are validity scales suggesting various denial patterns and deviant response sets. Profile of Mood States (POMS): T, tension; D, depression; A, anger; V, vigor; P, fatigue; C, confusion. "~l Sleep, Vol. 4, No.1, 1981

5 DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS Hs o Hy Pd Controls Narcoleptlcs, Apnelcs 1 1 * Mf Pa Pt Sc MMPI SCALES * Ma 51 L F K FIG. 1. Mean MMPI scale scores for controls, narcoleptics, and apneics. Asterisks indicate the level of statistical significance of comparisons between the indexed patient group and matched controls (*, p < 0.05; **, p < 0.01; ***, p < 0.001). A cross indicates a statistically significant (p < 0.05) difference between the two patient groups (apneics vs. narcoleptics). See Table I for the abbreviations used o T o A v F c t POMSSCALES FIG. 2. Mean POMS scores for controls, narcoleptics, and apneics. See Fig. I for the meaning of the symbols and Table 1 for the abbreviations used. Sleep, Vol. 4, No. I, 1981

6 44 L. E. BEUTLER ET AL. The stepwise analysis allowed all discriminating (p < 0.05) variables to be weighted according to their discriminative po\ver. The analysis was terminated at the point where the F to remove value ceased to be significant at the 0.05 level for all variables in the equation. Two scales [social introversion (Si) and vigor (V)] entered the stepwise discriminate function analysis as significant discriminators among the three groups. None ofthe remaining scales added significant improvement to the model. Table 2 summarizes the results for these two variables in discriminating between each pair of groups. From the right-most column of the table, it is evident that the model more easily distinguishes between controls and patients than between the two groups of patients. The bottom row shows that the POMS vigor scale is a more powerful discriminator than the MMPI social introversion scale. An interpretation of the model can be illustrated by the linear discriminant function comparing controls and narcoleptics: I = Si V If I > 0, classify as narcoleptic If I < 0, classify as control Thus we see that a low vigor score and a high social introversion score would characterize a narcoleptic patient in contrast to a control. The classification matrix for the above model is shown in Table 3. The control subjects were quite readily distinguished from either patient group (i.e., a high specificity for the model) by elevations in these two scales. Apneic patients were quite distinguishable from controls and narcoleptics, but narcoleptic patients were only moderately distinguishable from other groups using this model (i.e., only fair sensitivity). High-Point Pattern Analysis Results of the high-point pattern analyses are summarized in Table 4. It should be underlined that these analyses address a very different question than the previous two analyses. Namely, the two-point code analyses are performed without regard for actual scale elevations, but rather focuses on the most frequent scale patterns. In other words, the previous comparisons reflect intensity of disturbance as distinguishing characteristics, whereas pattern analysis addresses the type of characteristics which distinguish the groups. This analysis also differs from TABLE 2. Pairwise discrimination Coefficients of model Assigned group F value Comparison groups Si V Const if value >0 of model Controls vs. narcoleptics Narcoleptic 1O.35 b Controls vs. apneics Apneic 1O.59 b Narcoleptics vs. apneics Apneic 5.22" F to Remove of each scale 5.27" 1O.70 b a Statistically significant at the p < 0.01 level. b Statistically significant at the p < level. Sleep. Vol. 4. No. /. /98/

7 DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS 45 TABLE 3. Classification matrix Assigned group Percent Actual group Control Narcoleptic Apneic correct Control Narcoleptic Apneic discriminant analysis in that it initially focuses on each scale among groups. Thus, the high two-point profile for one group may distinguish it from another group even though the mean evaluations for the two scales in the profiles may be similar in both groups. What makes the two scales unique for one group is that their scores are high relative to those of the other scales in their own group. Because cell frequencies for the X2 analyses are small, the results must be interpreted with caution. Usually an expected cell frequency of 5 is considered necessary for reliable results. In a few instances, the results were based on an expected cell frequency of slightly less than 4. However, in view of the demonstration (Knetz, 1963) that expected cell frequencies as low as 2.5 still produce reliable results, we elected to proceed with the analyses. In all comparisons (Table 4) the two scales that characterized the MMPI profiles of each group significantly differentiated that group from each of the others, but did not distinguish between the other two groups. The control group was characterized either by having high femininity or manic scores relative to the other scores. Similarly, the narcoleptics were characterized as having either high anxiety or social introversion scores compared to their other scores, and the apneics as having relatively high hypochondriasis or hysteria scores. DISCUSSION The current findings support the general hypotheses that both the intensity of psychological symptoms and the dominant personality patterns of male apnea and narcoleptic patients distinguish them from one another and from normal controls. TABLE 4. Frequencies of two-paint-code patterns and X 2 results MMPI scale Group Mfor Ma Pt or Si Hs or Hy Controls (C) 8 I 1 Narcoleptic (N) Apneic (A) CxN 6.67 b 4.71" 1.47 CxA 4.59" b NxA b 6.64" a p < b P < See Table I for abbreviations. Sleep, Vol. 4, No. I, 1981

8 46 L. E. BEUTLER ET AL. At least within a male population, it is interesting to observe that the intensity of psychological symptoms, as well as the dominant personality pattern, success", fully distinguishes between collapsed groups of patients and normals. Distinctions between apnea and narcoleptic patients are more difficult to make on the basis of symptom intensity, however. Only in relative levels of social inhibition does the intensity of symptom differentiate between male apnea and male narcoleptic patients. While both tend to suffer from lack of vigor,compared to normals, the male sleep apnea patient is considerably less likely to become socially introverted in coping with the difficulty. As indicated, the intensity of psychological symptoms is most consistent in differentiating collapsed groups of apnea and narcolepsy patients from normal controls. However, the dominant personality patterns present in these groups, irrespective of symptom intensity, seem to distinguish the two patient groups quite reliably. Analysis of these dominant personality features (pattern analysis) suggests that narcoleptics are most often characterized by personality patterns which. emphasize coping with stress by sensitization to sources of anxiety and social withdrawal than are the other groups. In contrast, the personality styles of control subjects tend to be characterized by relative reliance on nonaggressive but externalized anxiety (dominant Ma and Mf MMPI patterns). These findings are consistent with the speculations of Broughton and Ghanem (1976), who suggest that narcoleptics may be more anxious and emotionally changeable than normals. Similarly, apnea patients appear to be more prone than normals to feel deficient in vigor. Again, as might be expected from their clinical condition, the pattern analysis suggests that their personality styles are more often oriented toward their physical well-being, dependency on external events, and physical symptoms than those of normals. ' The distinctions between apnea and narcoleptic patients are of particular interest since in the Sleep Disorders Center we often see apnea patients who have been misdiagnosed as narcoleptic prior to polysomnographic evaluation. The current findings suggest the presence of dependency needs which dominate other characteristics among the personalities of apnea patients, in contrast to those of narcoleptics. Apparently, apnea patients (at least males) tend to rely on denial and somatization as opposed to the narcoleptics' reliance on obsessiform and social distancing defenses. This latter pattern of emotional and social withdrawal among narcoleptics can perhaps be explained by their need to avoid situations in which cataplexy is likely to occur with embarrassing results. Nonetheless, both the ~: hysteroid and somatizing personality traits of the apnea patient and the social distancing and obsessiform traits of the narcoleptic stand in some contrast to normal, matched males who appear to be more frequently characterized by a physically active but philosophical approach to problems. While the 3 groups studied here may be differentiated from one another by the intensity of various psychological symptoms, the relative dominance of certain personality patterns within patient groups might more directly suggest the presence of a predisposing character type. More specifically, while the intensity of the narcoleptic patient's social withdrawal and lack of vigor might be a reflection of a reaction to the sleep disturbance itself, the relevant prevalence of hystrionic defenses among apnea patients Sleep, Vol. 4, No.1, 1981

9 DIFFERENTIATING PSYCHOLOGICAL CHARACTERISTICS 47 and obsessiform-introverted defenses among narcoleptics indicates contrasting defensive styles which either predispose or arise from the particular sleep disorder. The current data cannot directly provide information on whether the distinctions are a psychological consequence of the disorder or are predispositions to such disturbance. An ideal, but difficult, approach to this question would be to follow the development of sleep apnea and narcolepsy longitudinally. For example, one might study the children of patients who have these disorders. Another approach would be to reevaluate patients after successful treatment in order to determine if and how their dominant personality patterns might have changed. In any case, more precise determination of whether these and other personality characteristics represent preexisting attributes or consequences of a patient's medical condition is required in future research. While the current data indicate directions that may be of some significance, increasingly reliable and focused assessment tools designed to evaluate specific personality (i.e., introversion) and psychological symptom intensity might be.. employed to some value in further research efforts. Finally, the current data underline the interrelationships of psychological and physical disease processes. The data suggest that the question of treatment among both apneics and narcoleptics should be considered with reference to the personality characteristics and possible psychological dynamics that contribute to the patient's problems. REFERENCES Broughton R and Ghanem Q. The impact of compound narcolepsy on the life of the patient. In: C Guilleminault, WC Dement, and P Passouant (Eds): Proceedings of the First International Symposium on Narcolepsy, Montpelier, France, July, Dixon WJ (Ed). BMD Biomedical Computer Programs. University California Press, Los Angeles, Guilleminault C, van der Hoed J, and Mitler M. Clinical overview of the sleep apnea syndromes. In: C Guilleminault and Dement, WC (Eds), Sleep Apnea Syndromes, Alan R Liss, New York, Gunderson KE and Rahe RH (Eds), Life Stress and 1l1ness. Springfield, Ill, Charles C Thomas, Holmes TH and Rahe RH. The social readjustment rating scale. J Psychosom Res 11: , Kales A, Caldwell AB, Preston T A, Healey S, and Kales JD. Personality patterns in insomnia. Arch Gen Psychiatry 33: , Kimball CPo Conceptual development in psychosomatic medicine: Ann Intern Med 73: ,1970. Knetz W. An Empirical Study of the Effects of Selected Variables Upon the Chi Square Distribution. American Institute for Research, Washington, DC, Monroe JJ. Psychological and physiological differences between good and poor sleepers. J Abnorm Psychol 72: , Okada T, Ohta T, Miwa K, et al. Proceedings of the 9th International Congress of Electroencephalography and Clinical Neurophysiology. (Abstracted in Electroencephalogr Clin NeurophysioI42:540, 1977.) Neil JF, Spiker DG, Reynolds CF, et al. The myth of one illness: A patient with psychotic depression and mixed sleep apnea responsive to methylphenidate and thioridazine. Sleep Res 7:244, Richardson GS, Carskadon MA, Flagg W, van der Hoed J, Dement WC, Mitler MM. Quantitative differences between narcoleptic humans and control subjects, measured by a new clinical procedure, the multiple sleep latency test. Sleep Res 7:297, Roessler R. Personality, psychophysiology, and performance. Psychophysiology 10: , Sakai F, Meyer JS, Karacan I, et al. Narcolepsy: Regional cerebral blood flow during sleep and wakefulness. Neurology 29:61-67, Scheffe H. The Analysis of Variance. Wiley, New York, Williams RL, Karacan 1, Hursch CJ. EEG of Human Sleep: Clinical Applications. Wiley, New York, Sleep, Vol. 4, No.1, 1981