Information processing in chronic fatigue syndrome: a preliminary investigation of suggestibility.

This study examines the effects of certain types of information processing on the subjective experience of cognitive deficits in persons with chronic fatigue syndrome (CFS). Two groups of participants, persons with CFS and a group of healthy controls, were administered a symptom inventory and measures of intellectual functioning, memory, automatic processing, and suggestibility. The groups differed significantly on number and severity of reported symptoms and on measures of global suggestibility and automatic processing, but not on measures of intellectual functioning and memory. Suggestibility was related to number and severity of reported symptoms, as well as the inability to inhibit the automatic processing of information. Implications of these findings are discussed, as well as directions for future research and treatment of symptoms associated with CFS.

A twin study of chronic fatigue.

OBJECTIVE: The etiology of chronic fatigue syndrome is unknown, but genetic influences may be important in its expression. Our objective was to assess the role of genetic and environmental factors in unexplained chronic fatigue. METHODS: A classic twin study was conducted using 146 female-female twin pairs, of whom at least one member reported > or =6 months of fatigue. After completing questionnaires on symptoms, zygosity, physical health, and a psychiatric interview, twins were classified using three increasingly stringent definitions: 1) chronic fatigue for > or =6 months, 2) chronic fatigue not explained by exclusionary medical conditions, and 3) idiopathic chronic fatigue not explained by medical or psychiatric exclusionary criteria of the chronic fatigue syndrome case definition. Concordance rates in monozygotic and dizygotic twins were calculated for each fatigue definition along with estimates of the relative magnitude of genetic and environmental influences on chronic fatigue. RESULTS: The concordance rate was higher in monozygotic than dizygotic twins for each definition of chronic fatigue. For idiopathic chronic fatigue, the concordance rates were 55% in monozygotic and 19% in dizygotic twins (p =.042). The estimated heritability in liability was 19% (95% confidence interval = 0-56) for chronic fatigue > or =6 months, 30% (95% confidence interval = 0-81) for chronic fatigue not explained by medical conditions, and 51% (95% confidence interval = 7-96) for idiopathic chronic fatigue. CONCLUSIONS: These results provide evidence supporting the familial aggregation of fatigue and suggest that genes may play a role in the etiology of chronic fatigue syndrome.

Cognitive compromise following exercise in monozygotic twins discordant for chronic fatigue syndrome: fact or artifact?

This study examined the effects of exhaustive exercise on cognitive functioning among 21 monozygotic twin pairs discordant for chronic fatigue syndrome (CFS). The co-twin control design adjusts for genetic and family environmental factors not generally accounted for in more traditional research designs of neuropsychological function. Participants pedaled a cycle ergometer to exhaustion; maximum oxygen output capacity (VO2max) as well as perceived exertion were recorded. Neuropsychological tests of brief attention and concentration, speed of visual motor information processing, verbal learning and recognition memory, and word and category fluency were administered with alternate forms to participants pre- and postexercise. The preexercise neuropsychological test performance of CFS twins tended to be slightly below that of the healthy twin controls on all measures. However, twins with CFS did not demonstrate differential decrements in neuropsychological functioning after exercise relative to their healthy co-twins. Because exercise does not appear to diminish cognitive function, rehabilitative treatment approaches incorporating exercise are not contraindicated in CFS.

Motivating drinking behavior change depressive symptoms may not be noxious.

Depression often hinders behavior change among people who abuse alcohol; it adversely affects self-efficacy and is associated with poor outcomes. However, the Transtheoretical Stages of Change Model suggests that personal discomfort, namely if the costs of drinking outweigh the benefits, may lead to behavior change. Often such alcohol-related consequences are associated with depression. Seventy-five alcohol-abusing participants, ages 18-50, completed the Beck Depression Inventory (BDI), Losses Of Significance Self-report Questionnaire-Revised (LOSS-QR), Situational Confidence Questionnaire-42 (SCQ-42), the Brief Readiness to Change Questionnaire (RTC), and the Steady Pattern Chart (SP) at baseline and again 3 months later. BDI scores were significantly associated with all three RTC stage scores. LOSS-QR scores significantly predicted BDI scores but SCQ-42 scores did not. Interestingly, BDI scores did not predict changes in drinking rates over time. Greater levels of depressive symptoms, perhaps associated with awareness of negative drinking consequences, may promote rather than hinder motivation to change drinking behavior among people.

Circadian rhythm of core body temperature in subjects with chronic fatigue syndrome.

The pathophysiological basis for chronic fatigue syndrome (CFS) remains poorly understood. Certain symptoms of CFS, namely fatigue, neurocognitive symptoms and sleep disturbance, are similar to those of acute jet lag and shift work syndromes thus raising the possibility that CFS might be a condition associated with disturbances in endogenous circadian rhythms. In this study, we tested this hypothesis by examining the circadian rhythm of core body temperature (CBT) in CFS and control subjects. Continuous recordings of CBT were obtained every 5 min over 48 h in a group of 10 subjects who met the Center for Disease Control (CDC) definition of CFS and 10 normal control subjects. Subjects in the two groups were age, sex and weight-matched and were known to have normal basal metabolic rates and thyroid function. CBT recordings were performed under ambulatory conditions in a clinical research centre with the use of an ingestible radio frequency transmitter pill and a belt-worn receiver-logger. CBT time series were analysed by a cosinor analysis and by a harmonic-regression-plus-correlated-noise model to estimate the mean, amplitude and phase angle of the rhythm. The goodness of fit of each model was also compared using the Akaike Information Criterion (AIC) and sigma2. Average parameters for each group were compared by Student's t-test. By cosinor analysis, the only significant difference between CFS and control groups was in the phase angle of the third harmonic (P=0.02). The optimal harmonic-regression-plus-correlated-noise models selected were ARMA(1,1): control 7, CFS 6; ARMA(2,0): control 1, CFS 4; and ARMA(2,1): control 2 subjects. The optimal fit ARMA model contained two harmonics in eight of 10 control subjects but was more variable in the CFS subjects (1 harmonic: 5 subjects; 2 harmonics: 1 subject; 3 harmonics: 4 subjects). The goodness of fit measures for the optimal ARMA model were also better in the control than the CFS group, but the differences were not statistically significant. We conclude that, measured under ambulatory conditions, the circadian rhythm of CBT in CFS is nearly indistinguishable from that of normal control subjects although there was a tendency for greater variability in the rhythm. Hence, it is unlikely that the symptoms of CFS are because of disturbance in the circadian rhythm of CBT.

Comorbid clinical conditions in chronic fatigue: a co-twin control study.

OBJECTIVES: Chronically fatiguing illness, defined as fatigue for at least 6 months, has been associated with various physical health conditions. Our objective was to determine whether there is a significant relationship between chronically fatiguing illness and 10 clinical conditions that frequently appear to be associated with fatigue, adjusting for the potentially confounding effects of psychiatric illness. DESIGN: A co-twin control study controlling for genetic and many environmental factors by comparing chronically fatigued twins with their nonfatigued co-twins. SETTING: A nationally distributed volunteer twin registry. PARTICIPANTS: The study included 127 twin pairs in which one member of the pair experienced fatigue of at least 6 months' duration and the co-twin was healthy and denied chronic fatigue. Fatigued twins were classified into 3 levels using increasingly stringent diagnostic criteria. MEASUREMENTS AND MAIN RESULTS: Twins reported on a history of fibromyalgia, irritable bowel syndrome, multiple chemical sensitivities, temporomandibular disorder, interstitial cystitis, postconcussion syndrome, tension headache, chronic low back pain, chronic pelvic pain (women), and chronic nonbacterial prostatitis (men). The prevalence of these comorbid clinical conditions was significantly higher in the fatigued twins compared to their nonfatigued co-twins. Most notably, compared to their nonfatigued co-twins, the chronically fatigued twins had higher rates of fibromyalgia (> 70% vs < 10%) and irritable bowel syndrome (> 50% vs < 5%). The strongest associations were observed between chronic fatigue and fibromyalgia (odds ratios > 20), irritable bowel syndrome, chronic pelvic pain, multiple chemical sensitivities, and temporomandibular disorder (all with odds ratios > or = 4). Regression analysis suggested that the number of comorbid clinical conditions associated with chronic fatigue could not be attributed solely to psychiatric illness. CONCLUSIONS: Chronically fatiguing illnesses were associated with high rates of many other clinical conditions. Thus, patients with chronic fatigue may present a complex clinical picture that poses diagnostic and management challenges. Nonetheless, clinicians should assess such patients for the presence of comorbid clinical conditions. Future research should provide a better understanding of the temporal relationship of the onset of fatigue and these conditions, and develop strategies for early intervention.

Coping strategies in twins with chronic fatigue and chronic fatigue syndrome.

OBJECTIVES: Individuals with chronic fatigue and chronic fatigue syndrome (CFS) face debilitating symptoms as well as stressful life situations that may result from their condition. The goal of this study was to examine the coping strategies used by fatigue-discordant twin pairs. METHODS: We utilized a co-twin design to assess how twin pairs discordant for chronic fatigue and CFS cope with stress. All twin pairs were administered the Revised Ways of Coping Checklist. RESULTS: Overall, the pattern of coping strategies was similar for fatigued and non-fatigued twins. However, twins with chronic fatigue or CFS utilized more avoidance strategies than their non-fatigued counterparts; those with chronic fatigue also used more avoidance relative to problem-focused coping than their co-twins. CONCLUSIONS: These results suggest that while fatigue-discordant twins generally exhibit similar behavior patterns in order to cope with stress, there may be an association between fatigue and avoidance coping. Future research should focus on the role of avoidance and its relationship to fatiguing illnesses.

Executive cognitive function and heavy drinking behavior among college students.

Executive cognitive functions (ECFs) seem important for motivating change and self-regulation of problem drinking. Evidence for executive cognitive deficits have been found among heavy-drinking college students. Although college students who abuse alcohol often experience a variety of negative consequences related to their drinking behavior, executive cognitive dysfunction may interfere with recognizing consequences and responding skillfully to avoid future harm. Fifty college students with drinking problems completed assessments of ECFs. Greater negative drinking consequences and short-term memory function significantly predicted greater awareness of drinking problems. ECF may be an important factor for motivation to change drinking behavior among college students.

Assessment of psychological factors associated with adherence to medication regimens among adult patients with asthma.

Nonadherence with asthma medications is a significant problem associated with unnecessary functional limitations. The development of measures to assess psychological factors important to adherence with medication regimens among adult patients with asthma is described in the present report. The results indicated that the reliability and validity of the newly designed measures were adequate. Patients that did not perceive a need to take their medications as prescribed or those already taking their medications as prescribed had better pulmonary function. The results are discussed in terms of their implications for future studies, such as motivational interventions to enhance adherence with asthma medications.

Significant other responses are associated with fatigue and functional status among patients with chronic fatigue syndrome.

OBJECTIVE: The predictive power of partners' responses to illness behavior for illness outcomes was investigated among couples in which one person had chronic fatigue syndrome (CFS). METHODS: One hundred nineteen participants who met case-definition criteria for CFS and were living with a significant other (SO) completed self-report measures of relationship satisfaction, responses of their SO to fatigue symptoms, and outcome measures of fatigue and functional status. RESULTS: The results indicated that more frequent solicitous SO responses to illness behavior were predictive of greater fatigue-related severity and bodily pain. Solicitous SO responses to fatigue behavior were particularly influential in the context of a satisfactory relationship. In highly satisfactory relationships, solicitous SO responses were associated with significantly greater fatigue severity and fatigue-related disability than in relationships characterized by low or average satisfaction. CONCLUSIONS: Solicitous SO responses to CFS-related symptoms are associated with poorer patient outcomes, especially in the context of a satisfactory intimate relationship. Because of the cross-sectional nature of the study, the direction of effects cannot be interpreted unambiguously. SOs may be inadvertently positively reinforcing illness-related behavior: Solicitous partners may help the patient more with tasks of daily living, thereby decreasing the patient's activity level, which may lead to deconditioning and disability. Alternatively, patients with more severe symptoms and disability may present more opportunities for concerned SO responses, which again may be heightened in the context of a caring, satisfactory relationship. In either case, the results suggest that additional research on the role of solicitous SO responses is warranted.

Asthma patients and their partners: gender differences in the relationship between psychological distress and patient functioning.

This study investigated gender differences in the association between partners' psychological functioning, and patients' perceptions of health functioning and healthcare utilization. Participants were 50 couples in which one person had mild to moderate asthma. Patients and partners completed several questionnaires. Male patients reported significantly greater psychological distress and utilized fewer physician services than female patients. Furthermore, female patients' perceptions of health functioning and their physician utilization were negatively affected by their partners' psychological distress. The findings suggest a need for an interdisciplinary approach to asthma management and the possible inclusion of partners in treatment, especially for female patients.

The Chronic Fatigue Twin Registry: method of construction, composition, and zygosity assignment.

Chronic fatigue syndrome (CFS) and the symptom of chronic fatigue are conditions of unknown etiology. The Centers for Disease Control and Prevention (CDC) define CFS as an illness characterized by > or = 6 months of disabling fatigue associated with muscle pain, pharyngitis, and alterations in mood, sleep and neurocognition. We constructed a registry of twins with chronic fatigue to facilitate research on the impact of illness, the associated medical and psychosocial factors, and the heterogeneous proposed mechanisms for these conditions. We have recruited 204 twin pairs in which one or both members reported persistent fatigue through patient support group newsletters (60%), clinicians/researchers familiar with CFS (12%), notices placed on electronic bulletin boards for CFS (11%), twin organizations and researchers (6%), relatives and friends (3%) and other sources (8%). Complete data are available for 177 pairs (87%). Twins completed an extensive questionnaire booklet that included measures of physical and mental health, functional status, and psychosocial factors; a structured psychiatric interview was also conducted by telephone. Twins were classified using three increasingly more stringent diagnostic criteria for chronic fatigue: 1) > or = 6 months of fatigue (115 discordant and 61 concordant pairs); 2) chronic fatigue with additional symptoms and application of the medial exclusions of the CDC CFS case definition as obtained by self-report (92 discordant and 41 concordant pairs) and; 3) chronic fatigue with additional symptoms unexplained by self-reported medical conditions and psychiatric diagnoses as determined by the structured interview (69 discordant pairs and 25 concordant pairs). Despite the limitations of a volunteer registry, the Chronic Fatigue Twin Registry promises to be an important resource for research on CFS and chronic fatigue.

Neurocognitive dysfunction in dually-diagnosed patients: a potential roadblock to motivating behavior change.

Substance abuse has been associated with cognitive dysfunction, such as problems with attention, reasoning, and memory. Certain psychiatric disorders also have been associated with cognitive difficulties, thus placing dually-diagnosed patients at high risk for cognitive impairment that could interfere with successful entry into or completion of therapy. Twenty-two dually-disordered inpatients were administered the Brief Readiness to Change Questionnaire to measure levels of motivation to change substance use, and a neuropsychological test battery that included the Wechsler Adult Intelligence Scale-Revised (WAIS-R), the Halstead Category Test (HCT), and the Wechsler Memory Scale-Revised (WMS-R). Higher general intellectual, executive, and memory functioning were significantly related to greater scores in readiness to change substance abuse in this sample. Cognitive ability may be an important variable to consider in the motivation and treatment of dually-diagnosed patients.

Predictors of treatment adherence among asthma patients in the emergency department.

This study examined predictors of treatment adherence among 120 adult patients with asthma at two emergency departments (EDs). Structured medical chart reviews were performed for characteristics hypothesized to be associated with treatment adherence difficulties. Sixty percent of subjects had evidence of nonadherence with asthma treatment. Several variables were associated with nonadherence including younger age, more utilization of ED services (more ED visits, using the ED for medication refills), certain treatment characteristics (receiving more medications in the ED, not being prescribed prednisone at discharge), and not keeping post-discharge follow-up appointments. Further research should be directed at enhancing self-management skills and decreasing inappropriate ED use among nonadherent patients.

Regret, substance abuse, and readiness to change in a dually diagnosed sample.

The transtheoretical stages of change model posits that increased readiness to change is associated with greater awareness of the negative consequences of substance use. Experiencing regrets implies a greater awareness of these consequences. Eighty dually diagnosed patients completed a 22-item Measure of Substance-Related Regret (MSR) that assessed the intensity, type, idiographic importance of, and emotions associated with regrets related to substance use and the Brief Readiness to Change Questionnaire. The MSR yielded a global measure of regret that accounted for statistically significant amounts of variance in total readiness-to-change scores (R2 = .30). Global scores also predicted precontemplation and contemplation stage scores, whereas total fear scores associated with regrets predicted action scores. Regret seems to play a complex yet important role in the decision to change substance abuse.

Chronic fatigue syndrome: identification of distinct subgroups on the basis of allergy and psychologic variables.

BACKGROUND: We investigated a role for allergic inflammation and psychologic parameters in the development of chronic fatigue syndrome (CFS). METHODS: The design was a comparison between subjects with CFS and age- and sex-matched control cohorts. Studies were performed on CFS subjects (n = 18) and control cohorts consisting of normal subjects (n = 11), allergic subjects (n = 14), and individuals with primary depression (n = 12). We quantified cytokines at baseline as cell-associated immunoreactive peptides and as transcripts evaluated by means of semiquantitative RNA-based polymerase chain reactions. Psychologic evaluations included administration of the Diagnostic Interview Schedule, the Structured Clinical Interview, and the Symptom Checklist 90-Revised. RESULTS: Increases in tumor necrosis factor (TNF)-alpha were identified in individual subjects with CFS (50.1 +/- 14.4 pg TNF-alpha per 10(7) peripheral blood mononuclear cells [PBMCs]; mean +/- SEM) and allergic subjects (41.6 +/- 7.6) in comparison with normal subjects (13.1 +/- 8.8) (P < .01 and P < .05, respectively). Similar trends were observed for interferon (IFN)-alpha in allergic subjects (3.0 +/- 1.7 pg/10(7) PBMCs) and subjects with CFS (6.4 +/- 3.4) compared with normal subjects (1.9 +/- 1.4). A significant increase (P < .05) in TNF-alpha transcripts was demonstrated between subjects with CFS and depressed subjects. In contrast to these proinflammatory cytokines, both subjects with CFS (2.6 +/- 1.8 pg/10(7) PBMCs) and allergic subjects (3.4 +/- 2.8) were associated with a statistically significant (P < .01) decrease in IL-10 concentrations compared with normal subjects (60.2 +/- 18.2). As shown in other studies, most of our subjects with CFS were allergic (15 of 18) and therefore presumably demonstrated cytokine gene activation on that basis. The seasonal exacerbation of allergy was associated with a further increase in cellular IFN-alpha (from 2.1 +/- 1.2 to 14.2 +/- 4.5 pg/107 PBMCs; P < .05) but no further modulation of TNF-alpha or IL-10. Similarly, self-reported exacerbations of CFS were associated with a further increase in IFN-alpha (from 2.5 +/- 1.0 to 21.9 +/- 7.8; P < .05) and occurred at times of seasonal exposures to allergens. This linkage does not permit making any definitive conclusions regarding a causative influence of either seasonal allergies or the increase in cellular IFN-alpha with the increase in CFS symptoms. The close association between atopy and CFS led us to speculate that CFS may arise from an abnormal psychologic response to the disordered expression of these proinflammatory and antiinflammatory cytokines. Psychologic variables were predictive of immune status within the CFS sample (65.9% of the variance in immune status; F (3,10) = 6.44, P < .05). Specifically, the absence of a personality disorder but greater endorsement of global psychiatric symptoms was predictive of immune activation. CONCLUSIONS: Most of our subjects with CFS were allergic, and the CFS and allergy cohorts were similar in terms of their immune status. However, the CFS subjects could be discriminated by the distinct psychologic profiles among subjects with and without immune activation. We propose that in at least a large subgroup of subjects with CFS who had allergies, the concomitant influences of immune activation brought on by allergic inflammation in an individual with the appropriate psychologic profile may interact to produce the symptoms of CFS. In a psychologically predisposed individual, symptoms associated with allergic inflammation are recognized as illness.

Core body temperature is normal in chronic fatigue syndrome.

BACKGROUND: Subjects with chronic fatigue syndrome (CFS) frequently report symptoms of subnormal body temperature and low-grade fever. We conducted a study to determine whether CFS subjects manifest any abnormality of core body temperature (CBT) that might help explain their fatigue. METHODS: Continuous 24-hour recordings of CBT measured every 5 min were performed in 7 subjects meeting the Centers for Disease Control definition of CFS. Three additional groups were studied: normal controls, subjects with seasonal allergy, and subjects with major depression. Subjects (n = 7) in each group were age-, sex-, and weight-matched to the CFS group and had normal basal metabolic rates, thyroid function, and 24-hour urinary free cortisol excretions. CBT was measured with an ingestible radio frequency transmitter pill and a belt-worn receiver-logger. Each pill was factory-calibrated to +/- 0.1 degree C and field-calibrated with a water bath calibration prior to use. RESULTS: The 24-hour mean calibration-adjusted CBTs of each group were not significantly different (control: 37.00 +/- 0.17 degrees C; CFS: 37.04 +/- 0.31 degrees C; allergy: 37.15 +/- 0.18 degrees C; depression: 37.16 +/- 0.18 degrees C). Similarly, the mean peak and trough circadian temperatures were not statistically different. The mean 24-hour profile of CBT for each group showed a similar circadian rhythm. In simultaneously collected blood samples, each group showed a similar circadian profile of serum cortisol with a peak occurring at 08:00. CONCLUSIONS: Subjects with CFS have normal CBT despite frequent self-reports of subnormal body temperature and low-grade fever.

Specific classes of symptoms predict readiness to change scores among dually diagnosed patients.

The Transtheoretical Stages of Change model hypothesizes that disadvantages of substance abuse must outweigh advantages before change occurs. This study examined whether substance-related sequelae predicted readiness to change scores. A total of 150 dually diagnosed patients were administered the CAGE questionnaire (CAGE is an acronym for questions about substance use: Cutting down, Annoyed by criticism, feel Guilty, Early morning usage), which was scored for mood and behavior symptoms; a checklist of 12 physical, intrapersonal, and environmental symptoms; and the Brief Readiness to Change questionnaire (RTC). Regression analyses suggested that more physical and mood symptoms were predictive of higher total RTC (R2 = .11); physical, mood, and behavioral symptoms were predictive of higher contemplation scores (R2 = .17), whereas fewer physical symptoms were predictive of higher precontemplation scores (R2 = .05). The results suggest that the relative severity of physical, mood, and behavior symptoms may be important factors related to the contemplation of change among dually diagnosed patients.

Asthma and panic disorder.

OBJECTIVE: To compare asthma attacks with panic attacks and identify discriminating symptoms. DESIGN: Survey, case-control study. SETTING: Tertiary care centers. PATIENTS: Convenience sample of 71 patients with panic disorder, with or without agoraphobia, and without medical illnesses; and 71 patients with asthma, cohort-matched from 407 patients to be demographically similar to the panic disorder sample. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Asthma Symptom Checklist. RESULTS: Clusters of symptoms reflecting panic-fear and hyperventilation-hypocapnia were more strongly endorsed by subjects with panic disorder, whereas airway obstruction symptom clusters were more strongly descriptive of asthma attacks (all P < .05). Three symptoms differentiated the groups with sensitivity greater than 0.90 and specificity greater than 0.70: wheezing, mucous congestion, and coughing, all being present significantly more among asthma attacks than panic attacks. CONCLUSION: Knowledge of what symptoms discriminate asthma attacks from panic attacks may help physicians identify each type of attack in individuals who experience both.