Abstract
Introduction: Obsessive-Compulsive Disorder (OCD) is a common, chronic disorder which results in marked distress and impairment of social and occupational functioning. Sleep disturbance often accompanies mental disorders, but there have been few studies of sleep disturbance in OCD. These have produced contradictory findings, with some reporting sleep disruption, and others a normal sleep pattern.
The aim of the present study is to examine sleep patterns in OCD, to establish the frequency of the different types of insomnia (early, middle and late insomnia) in a sample of patients with OCD. The study also intends to determine whether the presence of a comorbid mood disorder influence frequency and type of insomnia.
Methods: all patients with a primary diagnosis of OCD (according to DSM-IV criteria) consecutively referred to the Mood and Anxiety Disorder Unit, Department of Neuroscience, University of Turin, from January 2003 to June 2008, were recruited. Frequency and severity of the different types of insomnia were evaluated on the basis of the Hamilton Depression Rating Scale (HDRS) specific items score (item 4-5-6). A statistical comparison between OCD patients with and without insomnia was performed to examine whether there was any difference in clinical features.
Then a statistical comparison between patients with and without depressive comorbidity was performed to examine whether there was any difference in prevalence and type of insomnia.
Results: The sample included 315 OCD patients. More than a half of the sample suffered from any type of insomnia. The most frequent type of insomnia was early insomnia (about 44,8%). We didn’t find a positive correlation between the severity measured with total Y-BOCS score or obsessions and compulsions sub-score clinical and socio-demographic features and insomnia. The presence of any comorbid depressive disorder increased the frequency of insomnia.
Conclusions: Insomnia, especially the early one, is a common symptom in OCD patients with or without comorbid depressive disorders. Late insomnia is typical of OCD with comorbid major depression.
Introduction
Sleep disturbance often accompanies mental disorders, and among insomniac subjects, about 30% have a psychiatric diagnosis [1;2]. Anxiety disorders are known to be associated with difficulties in initiating and maintaining sleep, and this association has been widely studied, although the ethio-pathogenetic issues regarding the association of the two groups of symptoms are not well elucidated [3;4]. Obsessive-Compulsive Disorder (OCD) is classified in the Diagnostic and Statistic Manual for Mental Disorders IV Edition – Text Revised (DSM-IV-TR) as an anxiety disorder, characterized by recurrent and persistent thoughts, impulses or images that are experienced as intrusive, that are not simply excessive worries about real-life problems, and that are recognized as a product of one’s mind and not based on reality, causing marked distress and impairment of social and occupational functioning. Obsessive thoughts evoke anxiety and compulsive behaviours or mental acts aimed at decreasing discomfort, or at preventing some dreaded event or situation: they are not actually connected to the issue or they are excessive, and they must be applied rigidly. The patients, at some point during the course of illness, become aware of the fact that those obsessions and compulsions are unreasonable and excessive. Moreover they are time consuming (more than one hour per day) and they cause marked distress. It is worth noting that insomnia is not included in the diagnostic criteria of OCD. OCD is a relatively common disorder: the lifetime prevalence is at 2-3% of the population [5;6]; the course is predominantly chronic.
There have been relatively few studies examining sleep in patients with obsessive-compulsive disorder and these have produced contradictory findings with some reporting sleep disruption, and others a normal sleep pattern.
Based on epidemiological findings, insomnia related to OCD had a prevalence of 0.2% while the prevalence of OCD with insomnia was 1.2% .[7;8] The evidence emerging from clinical sample nevertheless is that about 30% of patients suffer from some kind of insomnia [9]. Thus, we can assume that it is a well established fact that sleep disturbances are recognized to occur; however, their type and nature have been little studied and the contribution of comorbid depression has been difficult to disentangle from that of OCD. As a matter of fact, it is well known that individuals with OCD tend to suffer from comorbid depression at some time during the course of their illness. The proportion of patients fulfilling the criteria of Major Depressive Episode (MDE), often considered to be secondary to the OCD, has been estimated at between one-third [10] and two-thirds [11] of all cases, though detailed multivariate analysis of a large epidemiological sample suggested the proportion to be approximately 17% [12]. It is often when depressive symptoms supervene that individuals with OCD seek treatment for the first time. Similarly, it is a common finding in clinical samples the emerging of depressive symptoms after OCD onset. Moreover, the risk of developing a depressive episode tends to increase progressively with the duration of the Obsessive-Compulsive Disorder [13].
This topic represents a significant challenge for clinicians in the study of OCD and sleep disorders. Consequently, after investigating sleep architecture and neuro-endocrine features, researchers are called to understand if there is a common pathway, such as abnormalities in the serotoninergic system, implicated in the etiology of OCD and in the disregulation of sleep, or if the comorbidity with depression could shed light on the clinical and biological profile of sleep disruption.
Three rather recent studies investigated the comorbidity between OCD and depressive symptoms, providing indirect evidence about sleep pattern in depressed OCD patients. In a study carried out in 2004, Moritz and colleagues [9], with the aim of assessing the distribution of depressive symptoms in a large OCD sample (162 patients) and of analyzing the dimensional structure of the Hamilton Depression Rating Scale (HDRS) in OCD, found Major Depressive Disorder according to DSM-IV criteria in approximately one third of the patients. Sleep problems occurred in approximately one fifth of all patients, with the following distribution: 20.4% early insomnia, 14.2% middle insomnia and 13.6% late insomnia. It is interesting to point out the presence of ordering behavior and aggressive thoughts, as associated to more sleep problems.
Fineberg and coworkers [14], compared the clinical characteristics of a group of about 50 OCD patients with comorbid depression to an equivalent group of patients with MDD, examining between-group differences on the individual MADRS item scores. The study has demonstrated a difference between the depressive symptom profile of OCD patients with comorbid depression and that of severity-matched MDD patients. It is interesting that the OCD group was less symptomatic on items that measure a vegetative response to depression, such as sleep and appetite disturbance, that appear specific to MDD alone. This may suggest a different biological contribution from brain systems modulating sleep and appetite in this form of depression. The items in which symptoms of depression showed to be common to the two groups, were inner tension and pessimism, closer to core symptoms of OCD.
To conclude, it is important to mention a recent work that tries to shine light on the issue of comorbidity [15]: in this study, investigating a large sample (124 patients) of unmedicated and not-primarily depressed patients with OCD, an electroencephalographic investigation and an anti-5HT challenge test (tryptophan depletion) were used, in order to clarify whether comorbidity with depression is associated with abnormalities of sleep. This study indicates that neurobiological disturbances are different in primary OCD as compared with primary depression. Assuming that changes of sleep architecture indicate underlying neurobiological abnormalities, a relatively decreased 5-HT neurotransmission should be one contributing factor explaining the sleep abnormalities in depression, whereas not in OCD. The non specific disturbances of sleep continuity in OCD patients reported in the above mentioned study might be explained by a psycho-physiological hyper-arousal as a consequence of negative feelings, tension and anxiety associated with the obsessions and compulsions. This view is supported by the weak, but positive correlation between the severity of obsessions and compulsions and sleep continuity measures.
The recent biological research is focusing on specific facets of the problem, such as sleep architecture and neuroendocrine features: formerly Authors [16; 17; 18; 19] led studies about electro-encephalographic profiles of sleep in small OCD patients groups, finding weak, not peculiar and not unanimous evidence of decreased total sleep time, decreased REM efficiency and shortened REM latency.
Recently retrospective studies identified a possible association between OCD and sleep onset REM periods [20] or a circadian rhythm sleep disorder known as delayed sleep phase syndrome (DSPS), an uncommon condition in the general adult population in which patients go to bed and get up much later than normal, unable to shift their sleep to an earlier time[21; 22]. There is also some evidence for abnormalities in the circadian secretion of melatonin in patients with OCD [23], more pronounced in patients with more severe OCD based on higher Y-BOCS scores, and for alterations in sleep onset related to nocturnal GH secretion [24], and ACTH secretion [25], confirming an altered function of the somatotrophic axis in OCD.
Although there have been many studies investigating biological aspects of sleep, no real attention was paid to the patients sleeping pattern. Therefore we need to understand if patients are actually suffering from insomnia or not, and if depression could influence this symptom.
Consequently the aim of our study is to examine sleep pattern in a large sample of OCD patients (N= 315) and to establish the frequency of the different types of insomnia. Furthermore our intention is to determine the influence of comorbid depression on prevalence and phenomenology of insomnia.
Methods
Subjects
Subjects for this study were recruited from all patients with a principal diagnosis of OCD according to DSM-IV criteria consecutively referred to the Anxiety and Mood Disorders Unit, Department of Neuroscience, University of Turin (Italy) over a period of 5 years (January 2002- December 2007).
Diagnoses were established by means of a structured clinical interview, the SCID-I [26]. The Yale-Brown Obsessive-Compulsive Scale rating had to exceed 16 points [27]. Furthermore, patients had to be at least 18 years of age, and be willing to voluntarily participate to the study. Informed consent from patients was obtained after the procedure had been fully explained.
Exclusion criteria were considered a current or previous diagnosis of organic mental disorder, schizophrenia or other psychotic disorder, or having an uncontrolled or serious medical condition.
Diagnostic and Symptomatological Evaluation
A systematic face-to-face interview that consisted of structured and semi-structured components was used to collect data. Diagnostic evaluation and Axis I comorbidities were recorded by means of the Structured Clinical Interview for the DSM-IV Axis I Disorders [28].
All socio-demographic and illness characteristics were obtained through the administration of a semi-structured interview, developed and used in previous studies [29-3031] with a format that covered the following areas:
a) Socio-demographic data: age, sex, marital status (single, married, divorced, widowed), years of education.
b) Onset and course of OCD: disease onset was dated within a 1-month period as the first occurrence of obsessive and compulsive symptoms, and when at least one of them caused marked distress, was time consuming (more than one hour a day) or interfered with the person’s normal daily functioning (normal routine, occupational and social activities). An attempt was made to date onset of OCD to a 4-week period, but if there was uncertainty, a close relative of the patient was interviewed and a range was plotted and its mid-point was used in the analysis. The onset was considered abrupt when the symptoms reached clinically significant intensity within 1 week of onset. All other types of onset were considered insidious. When present, the interval occurred between the two moments (symptoms onset and disorder onset) of the patients’ clinical history was registered. The course of the disorder was considered episodic when at least one circumscribed symptom-free interval (6 months) was present; all other types of course were considered chronic, according to a definition we used in previous studies.
c) Obsessive-compulsive symptomatology: for each subject up to three primary obsessions and compulsions were listed using the Y-BOCS Symptom Check List.
To evaluate presence, degree and type of insomnia (early, middle or late) we considered the specific items (items 4, 5 and 6) of Hamilton Rating Scale for Depression (HAM-D) [32].
• presence of insomnia: score > 1 to item 4.5 or 6 of HAM-D)
• mean score for each item.
The interview and all the ratings were completed by psychiatrists with at least 4 years experience in anxiety and mood disorders. Each interviewer underwent a training program in the use of the interview instruments, which included direct observation of experienced interviewers, direct supervision of interviews, and inter-rater reliability. High reliability and diagnostic concordance have been documented in previous reports [31-33].
Statistical Analysis
We conducted analyses to determine:
1) if there was any difference in clinical features between OCD patients with and without insomnia;
2) if the presence of insomnia in OCD was correlated with actual comorbidity with mood disorders (Major Depressive Episode, Dysthymic Disorder and Depressive Disorder Not Otherwise Specified)
A statistical comparison between OCD patients with and without insomnia was performed to examine whether there was any difference in clinical features.
Then a statistical comparison between patients with and without depressive comorbidity was performed to examine whether there was any difference in prevalence and type of insomnia.
Our study was designed to provide descriptive information; therefore, primarily descriptive statistics were used to analyze the data. Between-group comparison of categorical variables was made with Pearson’s Chi-square test. Continuous variables were compared by using Student’s t test for two-class comparisons Given the exploratory nature of our study, we decided to use a 2-tailed significance level of p<.05. Bonferroni’s correction was applied when needed.
Results
Patients with a principal diagnosis of OCD enrolled in the study were 315. The demographic and clinical characteristics of the sample are presented in table 1 and table 2.
In our sample, 170 OCD patients out of 315 (54.0%) suffered from insomnia. Figure 1 represents the distribution of the subtypes of insomnia in the sample. Among these, 76 patients (24.1%) suffered from two or more types of insomnia. Prevalence of the subtypes of insomnia in the OCD sample was, respectively, 44.8% of patients suffering from early insomnia, 21.9% from middle insomnia and 18.4% from late insomnia. Figure 2 represents mean scores at each item for insomnia (4: early insomnia, 5 middle insomnia, 6 late insomnia) of the HAM-D. Mean scores of early insomnia were significantly higher than both middle (p<0.001) and late insomnia (p<0.001). There were no statistically significant differences between mean scores of item 5 and item 6 (p=0.924).
The clinical characteristics of the sample according to presence of insomnia are presented in table 3. The only statistically significant difference was the prevalence of aggressive obsessions; anyway, after Bonferroni’s correction the difference was no longer statistically relevant. Table 4 reports the differences in terms of prevalence of insomnia and its subtypes according to the presence or the absence of an actual depressive disorder in comorbidity with OCD.
Figure 1. prevalence of subtype of insomnia in the OCD sample (n=315).
Figure 2. Mean scores of HAM-D item 4 – 5 – 6 in OCD sample (n=315).
Table 1. Demographic and clinical characteristics of the sample.
|
Total N=315 |
|
|
Index age, mean (±SD), y |
34.9 (11.9) |
|
Educational level, mean (±SD), y |
12.1 (4.2) |
|
Marital status, n (%) |
|
|
Single |
165 (52.4) |
|
Married |
133 (42.2) |
|
Divorced |
14 (4.4) |
|
Widowed |
3 (1.0) |
|
Gender, n (%) |
|
|
Males |
159 (50.5) |
|
Females |
156 (49.5) |
|
Age at onset, mean (±SD), y: |
|
|
OCD |
22.7 (9.4) |
|
OCSa |
17.2 (8.8) |
|
Type of onset, n (%) |
|
|
Insidious |
214 (67.9) |
|
Abrupt |
101 (32.1) |
|
Type of course, n (%) |
|
|
Chronic |
257 (81.6) |
|
Episodic |
58 (18.4) |
|
Y-BOCS, mean (±SD) |
|
|
Total score |
24.8 (6.4) |
|
Obsession subscore |
13.1 (3.3) |
|
Compulsion subscore |
11.8 (4.2) |
|
HAM-D, mean (±SD) |
11.3 (6.3) |
|
Positive family history, n (%) |
|
|
OCD |
67 (21.3) |
|
Other Anxiety disorders |
35 (11.1) |
|
Mood disorders |
89 (28.3) |
|
Schizophrenia |
13 (4.1) |
a OCS = Obsessive-compulsive symptoms
Table 2. Obsessive-compulsive phenomenology according to the Y-BOCS Symptoms Check List in the sample.
|
Obsessions, n (%) |
Total N=315 |
|
Aggressive |
174 (55.2) |
|
Contamination |
171 (54.3) |
|
Sexual |
54 (17.1) |
|
Hoarding/saving |
45 (14.3) |
|
Religious |
85 (27.0) |
|
Symmetry/order |
151 (47.9) |
|
Somatic |
98 (31.1) |
|
Miscellaneous |
199 (63.2) |
|
Compulsions, n (%) |
|
|
Checking |
197 (62.5) |
|
Cleaning |
169 (53.7) |
|
Repeating |
159 (50.5) |
|
Ordering |
66 (21.0) |
|
Counting |
85 (27.0) |
|
Hoarding/collecting |
39 (12.4) |
|
Miscellaneous |
181 (57.5) |
Table 3. Comparison of clinical characteristic of obsessive-compulsive patients (315) with or without insomnia.
* not significant after Bonferroni’s correction (a=0.003)
Table 4. prevalence of insomnia in OCD: comparison between OCD patient without actual depressive disorder and OCD with an actual depressive disorder (Major Depressive Episode, Dysthymic Disorder or Depressive Disorder Not Otherwise Specified).
Conclusion
In the field of the interaction between sleep and psychiatric disorders, OCD is probably one of the least treated topics. This study to our knowledge is the largest study of sleep in OCD so far, and one of the few investigating clinical features of sleep in obsessive-compulsive disorder. As far as socio-demographic and clinical features are concerned, our sample was representative of the OCD population described in the scientific literature. We found that patients with OCD show abnormalities of sleep: more than 50% of our sample suffered from insomnia, about 24% reporting two or more types of insomnia. Our results did not confirm previous preliminary findings of the literature about clinical predictors of sleep disturbances in OCD [9; 15]: we didn’t find a positive correlation between the severity measured with total Y-BOCS score or obsessions and compulsions sub-scores and sleep clinical measures, neither between specific symptomatic dimensions and insomnia. Aggressive obsessions showed a trend toward significance that disappeared after Bonferroni’s correction. Concerning specific subtypes of insomnia, early insomnia was the most common kind of sleep disruption in our sample (44.8%), followed by middle (21.9%) and late (18.4%) insomnia. Early insomnia was also the most severe type of insomnia found in the sample. The findings mentioned above are difficult to compare with data presented in the literature, since they are scarce and extracted from small samples. Both epidemiological and clinical findings suggest a lower prevalence of sleep disturbances in OCD patients [7; 8; 9]. Moritz and colleagues, for example, found a similar distribution of subtypes of insomnia, but with lower rates, respectively 20.4% for early insomnia, 14.2% of middle insomnia and 13.6% of late insomnia. The finding of a prevalent early sleep disruption in OCD sample might be partly explained by a psycho-physiological hyper-arousal as a consequence of negative feelings, tension and anxiety associated with the obsessions and compulsions. Nevertheless, this hypothesis could not answer for any case of early insomnia nor for middle and late insomnia. Moreover, it has to be emphasized that nearly all our patients had a moderate to severe OCD (mean Y-BOCS total score: 24.8±6.4), in almost all cases lasting for many years and that 64% of the patients suffered from depression, 45% fulfilling criteria for Major Depressive Episode and 55% for depressive disorder other than MDE, with a mean HAM-D score of 11.3 (± 6.3). The comorbidity with depressive symptoms showed to be common in patients with severe OCD [8; 14; 15]: in fact the disorder could frequently be associated with secondary depressive symptoms. Since sleep abnormalities are a consistent finding in depression, it is important to compare clinical sleep measures of OCD patients with and without depressive symptoms. Any type of depression was significantly related to the presence of any kind of insomnia, consistently with the data of the scientific literature [8; 14; 15].
In conclusion, our results about prevalence of insomnia are quite different from those presented in the literature: the explanation could be found in the characteristics of the sample studied. We lead the investigation on a clinical sample of moderate to severe OCD patients with high rates of depressive symptoms. These features evidently could predispose patients to insomnia, as a consequence both of negative feelings and inner tension disturbing the sleep and of the comorbidity with depression of which insomnia is a core symptom.
As mentioned above, the strength of the present study is supported by the investigation of clinical features of sleep in OCD with and without comorbid depression, carried out on a wide sample. The main limitations of this study are the retrospective design and the fact that the sleep record had not involved the use of standardized instruments apart from the three specific sub-items of the Hamilton Depression Rating Scale. Therefore, the two major conclusions from this study remain that OCD patients seem to exhibit significant rates of insomnia, and that depressive symptoms, either in the context of a Major Depressive Episode or in that of a depressive disorder other than MDE, produce a worsening of sleep abnormalities.
