Introducing the DizzyQuest: an app-based diary for vestibular disorders.

BACKGROUND: Most questionnaires currently used for assessing symptomatology of vestibular disorders are retrospective, inducing recall bias and lowering ecological validity. An app-based diary, administered multiple times in daily life, could increase the accuracy and ecological validity of symptom measurement. The objective of this study was to introduce a new experience sampling method (ESM) based vestibular diary app (DizzyQuest), evaluate response rates, and to provide examples of DizzyQuest outcome measures which can be used in future research. METHODS: Sixty-three patients diagnosed with a vestibular disorder were included. The DizzyQuest consisted of four questionnaires. The morning- and evening-questionnaires were administered once each day, the within-day-questionnaire 10 times a day using a semi-random time schedule, and the attack questionnaire could be completed after the occurrence of a vertigo or dizziness attack. Data were collected for 4 weeks. Response rates and loss-to-follow-up were determined. Reported symptoms in the within-day-questionnaire were compared within and between patients and subgroups of patients with different vestibular disorders. RESULTS: Fifty-one patients completed the study period. Average response rates were significantly higher than the desired response rate of > 50% (p < 0.001). The attack-questionnaire was used 159 times. A variety of neuro-otological symptoms and different disease profiles were demonstrated between patients and subgroups of patients with different vestibular disorders. CONCLUSION: The DizzyQuest is able to capture vestibular symptoms within their psychosocial context in daily life, with little recall bias and high ecological validity. The DizzyQuest reached the desired response rates and showed different disease profiles between subgroups of patients with different vestibular disorders. This is the first time ESM was used to assess daily symptoms and quality of life in vestibular disorders, showing that it might be a useful tool in this population.

White noise speech illusions in the general population: The association with psychosis expression and risk factors for psychosis.

INTRODUCTION: Positive psychotic experiences are associated with increased rate of white noise speech illusions in patients and their relatives. However, findings have been conflicting to what degree speech illusions are associated with subclinical expression of psychosis in the general population. The aim of this study was to investigate the link between speech illusions and positive psychotic experiences in a general population sample. In addition, the hypothesis that speech illusions are on the pathway from known risk factors for psychosis (childhood adversity and recent life events) to subthreshold expression of psychosis, was examined. METHODS: In a follow-up design (baseline and 6 months) the association between the number of white noise speech illusions and self-reported psychotic experiences, assessed with the Community Assessment of Psychic Experiences (CAPE), was investigated in a general population sample (n = 112). In addition, associations between speech illusions and childhood adversity and life events, using the Childhood Experiences of Care and Abuse questionnaire and the Social Readjustment Rating Scale, were investigated. RESULTS: No association was found between the CAPE positive scale and the number of white noise speech illusions. The CAPE positive scale was significantly associated with childhood adversity between 12 and 16 years (B = 0.980 p = 0.001) and life events (B = 0.488 p = 0.044). The number of speech illusions showed no association with either life events or childhood adversity. CONCLUSION: In the nonclinical population, the pathway from risk factors to expression of subclinical psychotic experiences does not involve white noise speech illusions as an intermediate outcome.

Cortical processes of speech illusions in the general population.

BACKGROUND: There is evidence that experimentally elicited auditory illusions in the general population index risk for psychotic symptoms. As little is known about underlying cortical mechanisms of auditory illusions, an experiment was conducted to analyze processing of auditory illusions in a general population sample. In a follow-up design with two measurement moments (baseline and 6 months), participants (n = 83) underwent the White Noise task under simultaneous recording with a 14-lead EEG. An auditory illusion was defined as hearing any speech in a sound fragment containing white noise. RESULTS: A total number of 256 speech illusions (SI) were observed over the two measurements, with a high degree of stability of SI over time. There were 7 main effects of speech illusion on the EEG alpha band-the most significant indicating a decrease in activity at T3 (t = -4.05). Other EEG frequency bands (slow beta, fast beta, gamma, delta, theta) showed no significant associations with SI. CONCLUSION: SIs are characterized by reduced alpha activity in non-clinical populations. Given the association of SIs with psychosis, follow-up research is required to examine the possibility of reduced alpha activity mediating SIs in high risk and symptomatic populations.

The Experience Sampling Method--a new digital tool for momentary symptom assessment in IBS: an exploratory study.

BACKGROUND: Retrospective questionnaires are frequently used for symptom assessment in irritable bowel syndrome (IBS) patients, but are influenced by recall bias and circumstantial and psychological factors. These limitations may be overcome by random, repeated, momentary assessment during the day, using electronic Experience Sampling Methodology (ESM). Therefore, we compared symptom assessment by ESM to retrospective paper questionnaires in IBS patients. METHODS: Twenty-six IBS patients (Rome III) were included, of which 16 were diagnosed with panic disorder (DSM-IV-TR). Patients scored symptoms using end-of-day diaries during 14 days and the gastrointestinal symptom rating scale (GSRS) once. ESM was used on seven consecutive days during the same time period. KEY RESULTS: End-of-day diary abdominal pain scores were 0.4 (SE 0.1, p < 0.001) point higher (on a 1-to-5-point scale) compared to corresponding ESM mean-scores in IBS patients. The difference was even more pronounced for upper abdominal pain scores assessed by the GSRS (4.77 ± 1.50) compared to ESM mean-scores (2.44 ± 1.30, p < 0.001), both on 1-to-7-point scale. For flatulence, comparable results were found. Nausea and belching scores showed small, but significant differences between end-of-day diary and ESM. All tested symptoms were scored higher on GSRS compared to ESM mean-scores (p < 0.01). Affective comorbidity did not influence differences in pain reporting between methods. CONCLUSIONS & INFERENCES: IBS patients report higher scores for abdominal pain in retrospective questionnaires compared to ESM, with a tendency to report peak rather than average pain scores. ESM can provide more insight in symptom course and potential triggers, and may lead to a better understanding of IBS symptomatology.

The association between motor subtypes and psychopathology in Parkinson's disease.

BACKGROUND: In Parkinson's disease (PD) it has been suggested that various motor subtypes are also characterized by a different prevalence and severity of specific non-motor symptoms such as cognitive deterioration, depression, apathy and hallucinations. The aim of this study was to investigate the association between motor subtypes and psychopathology in PD. METHODS: An exploratory and confirmatory cluster analysis of motor and psychopathological symptoms was performed with a randomized sample of 173 patients each, stemming from two research databases: one from Stavanger University Hospital and one from Maastricht University Hospital. These databases contained data of standardized assessments of patients with the Unified Parkinson's Disease Rating Scale, the Montgomery-Asberg Depression Rating Scale, and the Mini-Mental State Examination. RESULTS: PD patients can be accurately and reliably classified into four different subtypes: rapid disease progression subtype, young-onset subtype, non-tremor-dominant subtype with psychopathology and a tremor-dominant subtype. Cognitive deterioration, depressive and apathetic symptoms, and hallucinations all cluster within the non-tremor-dominant motor subtype, that is characterized by hypokinesia, rigidity, postural instability and gait disorder. CONCLUSIONS: This study shows that non-tremor-dominant PD is associated with cognitive deterioration, depression, apathy, and hallucinations, which has implications for future research into the pathophysiology of psychopathology in PD.

Altered omega-3 polyunsaturated fatty acid status in depressed post-myocardial infarction patients.

OBJECTIVE: Lower levels of long-chain omega-3 polyunsaturated fatty acids (n-3 LCPUFAs) and increased inflammation have been associated with both depressive disorder and myocardial infarction (MI). The present study investigated whether patients who develop depression post-MI, have higher arachidonic acid/eicosapentanoic acid (AA/EPA) ratios than non-depressed post-MI patients and whether depressed post-MI patients have signs of increased inflammation as measured by C-reactive protein (CRP). METHOD: Serum AA/EPA ratio and plasma CRP levels were quantified in 50 post-MI patients, of which 29 were depressed and 21 non-depressed. RESULTS: Compared with the non-depressed group, depressed post-MI patients had significantly higher AA/EPA ratios. No significant difference was observed in CRP levels. CONCLUSION: Depressed post-MI patients had lower levels of n-3 LCPUFAs as measured by mean AA/EPA ratio and no signs of increased inflammation as determined by CRP levels.

Focal or generalized vascular brain damage and vulnerability to depression after stroke: a 1-year prospective follow-up study.

BACKGROUND: Both the lesion location hypothesis and the vascular depression hypothesis have been proposed to explain the high incidence of depression in stroke patients. However, research studying both hypotheses in a single cohort is, at present, scarce. OBJECTIVE: To test the independent effects of lesion location (left hemisphere, anterior region) and of co-occurring generalized vascular damage on the development of depression in the first year after ischemic stroke, while other risk factors for depression are controlled for. METHODS: One hundred and ninety consecutive patients with a first-ever, supratentorial infarct were followed up for one year. CT was performed in the acute phase of stroke, while in 75 patients an additional MRI scan was also available. Depression was assessed at 1, 3, 6, 9, and 12 months after stroke using self-rating scales as screening tools and the SCID-I to diagnose depression according to DSM-IV criteria. RESULTS: Separate analyses of the lesion location hypothesis and the vascular depression hypothesis failed to reveal significant support for either of these biological models of post-stroke depression. Similar negative results appeared from one overall, multivariate analysis including variables of both focal and generalized vascular brain damage, as well as other non-cerebral risk factors. In addition, level of handicap and neuroticism were independent predictors of depression in this cohort, as has been reported previously. CONCLUSION: This study supports neither the lesion location nor the vascular depression hypothesis of post-stroke depression. A biopsychosocial model including both premorbid (prior to stroke) vulnerability factors, such as neuroticism and (family) history of depression, as well as post-stroke stressors, such as level of handicap, may be more appropriate and deserves further study.

Cognitive performance after first ever stroke related to progression of vascular brain damage: a 2 year follow up CT scan study.

BACKGROUND: Stroke is one of the most common causes of cognitive impairment in the elderly. Ischaemic brain damage (white matter lesions and silent infarcts) progresses in a substantial number of stroke patients. The aim of this study was to investigate whether the progression of ischaemic brain damage is associated with cognitive functioning after first ever stroke. METHODS: A total of 101 stroke patients were followed up for 2 years. Neuropsychological functioning was assessed at 1, 6, 12, and 24 months after stroke. Computed tomography was performed on all patients at baseline and 2 years after stroke. Progression in white matter lesions and (silent) infarcts was recorded. RESULTS: Patients with progressive vascular brain damage performed worse on cognitive tasks, both 1 and 24 months after stroke, yet change in cognitive functioning was not different from that of patients without progressive vascular damage. During the follow up, improvement was noticed on most cognitive domains. CONCLUSIONS: Although patients with progressive vascular brain damage after a first stroke performed somewhat worse on cognitive tests than those without such damage, both groups showed an improved or stable performance 2 years later. Thus, there is not a simple relation between progression of ischaemic brain damage and decline in cognitive functioning after first ever stroke.

Predictive accuracy of MCI subtypes for Alzheimer's disease and vascular dementia in subjects with mild cognitive impairment: a 2-year follow-up study.

AIM: The aim of this study was to investigate the prognostic accuracy of different subtypes of mild cognitive impairment (MCI): amnestic MCI, multiple domain MCI, and single non-memory domain MCI, for the development of Alzheimer's dementia (AD) and vascular dementia (VaD). PATIENTS: Nondemented patients from a memory clinic cohort (n = 118), and a stroke cohort (n = 80, older than 55 years and with a cognitive impairment). RESULTS: 'Multiple domain MCI' had the highest sensitivity for both AD (80.8%) and VaD (100%), and 'amnestic MCI' had the highest specificity (85.9% for AD, 100% for VaD). The positive predictive value was low for all subtypes (0.0-32.7%), whereas the negative predictive value was high (72.8-100%). DISCUSSION: The subtype 'multiple domain MCI' has high sensitivity in identifying people at risk for developing AD or VaD. The predictive accuracy of the MCI subtypes was similar for both AD and VaD.

Demographic and CT scan features related to cognitive impairment in the first year after stroke.

OBJECTIVE: Little is known about the relation between stroke related features and cognitive performance over time when stroke patients with dementia or less severe cognitive disorders are considered separately. We aimed to study the features (computed tomography (CT) scan and demographic) that could be related to vascular cognitive impairment one, six, and 12 months after stroke. METHODS: A total of 176 patients with a first-ever brain infarct, a Mini Mental State Examination score > or = 15, age older than 40 years, and without pre-stroke dementia and other neurological or psychiatric disorders participated in this study. The following CT scan features were recorded: side of infarct, lacunar or territorial infarct, white matter lesions, silent infarcts, and brain atrophy. The demographic features studied were: age, level of education, and sex. Univariate and multivariate logistic regression analyses were performed to compare the three groups of patients (patients with dementia, patients with vascular cognitive impairment (VCI), and patients with vascular mild cognitive impairment (MCI)) with patients without cognitive disorders. RESULTS: At one month none of the variables were predictors of dementia; at six months older age (odds ratio (OR) 9.4), low education (OR 14.7), and territorial infarct (OR 10.6) predicted dementia; and at 12 months low education (OR 8.7) and pre-stroke cerebrovascular damage (OR 7.4) predicted dementia. Predictors of VCI were low education (OR 3.4) and territorial infarct (OR 2.4) at one month post stroke; older age (OR 4.3) and low education (OR 4.1) at six months; and older age (OR 3.5) at 12 months. Predictors of vascular MCI were low education (OR 4.96) and territorial infarct (OR 3.58) at one month; and older age and lower education at six months (OR 3.4 and 3.7, respectively) and at 12 months (OR 3.5 and 2.28, respectively). CONCLUSIONS: Territorial infarct, older age, and low educational level are predictors of cognitive disorders after stroke.

A comparative study into the one year cumulative incidence of depression after stroke and myocardial infarction.

BACKGROUND: The high incidence of post-stroke depression has been claimed to reflect a specific, stroke related pathogenesis in which lesion location plays an important role. To substantiate this claim, post-stroke depression should occur more often than depression after another acute, life threatening, disabling disease that does not involve cerebrovascular damage. OBJECTIVES: To compare the cumulative one year incidence of depression after stroke and after myocardial infarction, taking into consideration differences in age, sex, and the level of handicap. METHODS: In a longitudinal design, 190 first ever stroke patients and 200 first ever myocardial infarction patients were followed up for one year. Depression self rating scales were used as a screening instrument to detect patients with depressive symptoms. Major and minor depression was assessed at one, three, six, nine, and 12 months after stroke or myocardial infarction according to DSM-IV criteria, using the structured clinical interview from DSM-IV. The severity of depressive symptoms was measured with the Hamilton depression rating scale. Level of disability and handicap was rated with the Rankin handicap scale. RESULTS: The cumulative one year incidence of major and minor depression was 37.8% in stroke patients and 25% in patients with myocardial infarction (hazard ratio 1.6; p = 0.06). This difference disappeared after controlling for sex, age, and level of handicap. In addition, no differences were found in the severity of depressive symptoms or in the time of onset of the depressive episode after stroke or myocardial infarction. CONCLUSIONS: Depression occurs equally often during the first year after stroke and after myocardial infarction when non-specific factors such as sex, age, and level of handicap are taken into account. Thus the relatively high incidence of post-stroke depression seems not to reflect a specific pathogenic mechanism. Further research is needed to investigate whether vascular factors play a common role in the development of depression after stroke and myocardial infarction.

The contribution of somatic symptoms to the diagnosis of depressive disorder in Parkinson's disease: a discriminant analytic approach.

This study assessed the sensitivity of individual depressive symptoms and their relative contribution to the diagnosis of depressive disorder in patients with Parkinson's disease. The Structured Clinical Interview for DSM-IV Depression and the Hamilton and Montgomery-Asberg depression rating scales (Ham-D, MADRS) were administered to 149 consecutive nondemented patients. The contribution of the individual items of these scales to the diagnosis of "depressive disorder" was calculated by discriminant analysis. The discriminant models based on the Ham-D and MADRS scores were both highly significant. Nonsomatic core symptoms of depression had the highest correlation coefficient. Somatic items had mostly low correlation coefficients, with the exception of reduced appetite and early morning wakening (late insomnia). Nonsomatic symptoms of depression appear to be the most important for distinguishing between depressed and nondepressed patients with Parkinson's disease, along with reduced appetite and early morning awakening.

Cardiological risk factors for depressive symptoms after a first myocardial infarction.

OBJECTIVE: To detect possible cardiological risk factors in the acute phase of MI for developing depressive symptoms after first MI. DESIGN: Retrospective analysis of cardiac and psychiatric data of 111 consecutive patients admitted with a first MI. METHODS: During one year, all consecutive patients with a first MI, less than 12 hours chest pain and a maximal aspartate aminotransferase (ASAT) value of at least 80 U/l, admitted to the University Hospital of Maastricht, were screened for the presence of depressive symptoms using the 90-item 'Symptom checklist' (SCL-90) questionnaire at one month post-MI. Inclusion criteria were fulfilled by 111 patients; 28 patients refused to participate in the study. RESULTS: No correlation was found between LVEF, peak ASAT, peak CK value and characteristics, location or mode of treatment of the MI and depressive symptoms post-MI. A statistically significant negative correlation was found between SCL-90 depression score and cardiac tissue loss as defined by cumulative ASAT release at 24, 48 and 72 hours after the acute event (p values 0.029, 0.028 and <0.009, respectively) at the one month post-MI screening. CONCLUSIONS: No cardiological parameters were correlated to depressive symptoms post-MI. If there was a connection at all, this appeared to be a negative correlation between infarct size as measured by ASAT release and the occurrence of depressive symptoms at one month post-MI.

Vascular cognitive disorders: memory, mental speed and cognitive flexibility after stroke.

This study investigated the occurrence of cognitive disorders 1 and 6 months after stroke in a cohort of patients with a first-ever stroke. In addition, it was investigated whether age, sex and level of education are risk factors for vascular cognitive disorders. Memory, simple speed, cognitive flexibility and overall cognitive functioning were examined in 139 patients at 1 and 6 months post-stroke. Inclusion criteria on admission were first cerebral stroke, age>/=40, no other neurological or psychiatric disorders and ability to communicate. Mean age was 69.3 years (S.D.=12.3). Patients were compared with a healthy control group matched for age, sex and level of education. A large group of patients who, at 1 month after stroke, scored below the cutoff on cognitive domains, scored above the cutoff on most of these cognitive domains at 6 months. For overall cognitive functioning, 16 out of 39, for memory, 13 out of 26 and for cognitive flexibility, 15 out of 49 patients, who at 1 month scored below the cutoff, scored above the cutoff at 6 months. Simple speed did not change; 12 patients scored above the cutoff and 7 patients scored below the cutoff at 6 months after stroke. Speaking in terms of improvement or deterioration, most people remained stable on the four cognitive domains (ranging from 37.6% to 83.5%), and a substantial group improved (ranging from 12.9% to 52.1%). Older and female patients had more cognitive disturbances. Overall, the conclusion is that the prognosis of cognitive functioning after stroke is general favourable, especially in younger patients.

Daily hassles and stress vulnerability in patients with a whiplash-associated disorder.

The objectives of this study were to examine the self-reported, daily problems of patients with a whiplash-associated disorder (WAD) and a healthy control group, with the hypothesis that WAD patients would report more person-dependent hassles and perceive them as more serious than the healthy control group, due to the prior experience of a whiplash injury. In addition, it was expected that the person-independent seriousness rating would be elevated, reflecting the increased vulnerability of WAD patients to common stressors. Finally, a strong relationship was expected between frequency or seriousness of daily problems on the one hand and level of distress on the other. Forty-seven WAD patients seeking treatment and 47 matched healthy control participants completed the everyday problem checklist (EPCL). The level of distress was measured by the symptom checklist (SCL-90). As expected, most EPCL-scores in the WAD group were higher than the scores of the healthy participants. Regression analysis further revealed that 61% of the variance in general distress in the WAD group could be explained by EPCL scores and educational background. Chronic WAD patients report a high stress load, which is related specifically to personal functioning after the whiplash injury. In addition, WAD patients (especially those with a low educational level) appear to be more vulnerable and react with more distress than healthy people to all kinds of stressors. Stress responses probably play an important role in the maintenance or deterioration of whiplash-associated complaints.

Markers for depression in Parkinson's disease.

OBJECTIVE: To assess whether general risk factors for depression are also markers of depression in patients with Parkinson's disease (PD) and to identify additional disease-specific markers. METHOD: A two-step logistic regression was performed on data from 161 consecutively referred PD patients, 40 of whom suffered from major depressive disorder. A first logistic model was created with five general risk factors for depression. Next, five potential disease-specific markers were added to see whether this would improve the model. RESULTS: The logistic model of general risk factors for depression also predicted depression in PD patients. A family history of depression was the most important marker. 'Right-sided onset' was the only disease-specific marker that improved the model. CONCLUSION: Established risk factors for depression in the general population are also markers of depression in PD. The importance of correcting for general risk factors for depression in the search for disease-specific risk factors is stressed.

Sensitivity and specificity of observer and self-report questionnaires in major and minor depression following myocardial infarction.

This study evaluated screening abilities of self-report questionnaires for depression in first myocardial infarction (MI) patients. One month post-MI, 206 patients with first MI were screened for major and minor depression using the 90-item Symptom Check List (SCL-90), the Beck Depression Inventory (BDI), the Hospital Anxiety and Depression Scale (HADS), and the 17-item Hamilton Depression Rating Scale (Ham-D). The Structured Clinical Interview for DSM-IV criteria was used as the gold standard. Sensitivity and specificity for different cutoff points, using relative operating characteristics curves, were assessed. The internal consistency for all scales was good. When screening for major and minor depression, the optimal cutoff scores are lower than those for screening major depression only. The SCL-90, BDI, HADS, and Ham-D proved to have acceptable abilities for screening post-MI major and minor depression.

Research into the specificity of depression after stroke: a review on an unresolved issue.

Iwo decades of research have failed to generate consistent insight into the specificity of poststroke depression (PSD). This is, at least in part, caused by methodological difficulties. Differences in symptom profile between PSD and depression with no or another medical cause were described, but no specific and unequivocal clinical picture has been established so far. Prevalence rates of PSD varied largely between studies. In community based studies using standardised diagnostic instruments for depression, relatively low prevalence rates were reported compared to inpatient or rehabilitation studies. PSD occurs most frequently in the first few months after stroke, while a new incidence peak may occur 2-3 years after stroke. Two systematic reviews on the relation between lesion location and depression did not support the claim that left hemisphere lesions are a risk factor for PSD. A new concept of vascular depression has been proposed, which relates depression in the elderly to acute or chronic damage to the cerebral vascular system. Future efforts should aim at increasing the uniformity of study designs, assessment tools should be further improved for use in cognitively impaired patients and appropriate control groups should be defined to study the characteristic features of PSD.

Clinical correlates of depression following myocardial infarction.

OBJECTIVE: Post-MI depression increases mortality, especially in the first 18 months after MI. Identifying patients at risk for post-MI depression is therefore important. In the present study we investigated possible correlates for post-MI depression on an a priori basis. METHOD: Based on the literature, four clinically easily attainable variables were selected as possible correlates for post-MI depression. These were prescription of benzodiazepines during acute hospitalization, cardiac complications during acute hospitalization, history of depression, and not being able to stop smoking within six months after MI. A consecutive cohort of 173 first-MI patients was screened with the SCL-90 depression scale and DSM-III-R criteria for major depression. Of this cohort 35 depressed patients were compared with 35 non-depressed post-MI patients, matched for gender, age, and severity of MI. RESULTS: In univariate analyses, complications during hospitalisation (OR = 2.14; CI = 0.89-5.14), prescription of benzodiazepines (OR = 3.67; CI = 1.11-12.1), history of depression (OR = 3.0; CI = 0.87-10.4), and not being able to stop smoking (OR = 4.5; CI = 1.11-18.2) were clinical correlates for post-MI depression. Multivariate analyses showed that none of these variables were independent of the others in predicting depression. CONCLUSIONS: A number of easily measurable patient characteristics identify those MI-patients at risk of post-MI depression. Further investigations should focus on the predictive value of these factors in relation to post-MI depression.

The relationship between depressive and vital exhaustion symptomatology post-myocardial infarction.

OBJECTIVE: Many peri-myocardial infarction patients experience decreased wellbeing, which is either conceptualized as depression or as vital exhaustion. The objective of the present study is to investigate whether or not depression and vital exhaustion are separate entities. It was hypothesized that, if depression and vital exhaustion are separate phenomena, the correlation between two depression questionnaires would be higher than those between either of the two depression questionnaires and a vital exhaustion questionnaire. METHOD: Subjects were 143 patients who had recently experienced a first acute myocardial infarction (MI). At 1, 3, 6 and 12 months post-MI, patients completed two self-report depression questionnaires (the Zung-SDS and the Depression scale of the SCL-90), and a vital exhaustion questionnaire (the Maastricht Questionnaire). Correlation coefficients were calculated for the two depression questionnaires and the vital exhaustion questionnaire. Furthermore, an exploratory principal component analysis was performed on the combined items of the three questionnaires. RESULTS: Strong and virtually identical correlations were found between the three measures at all four time-points. A one-factor model was the best fit in the exploratory principal component analysis. CONCLUSION: The present results do not support the hypothesized separate conceptual identity of depression and vital exhaustion.