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ORIGINAL ARTICLE Table of Contents  
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A cross-sectional study of insomnia severity and cognitive dysfunction in bipolar disorder and schizophrenia patients under remission


1 Senior Resident, Department of Psychiatry, Telangana Institute of Medical Sciences, Hyderabad, Telangana, India
2 Associate Professor, Department of Psychiatry, Government Medical College, Nizamabad, Telangana, India
3 Associate Professor, Department of Psychiatry, Kakathiya Medical College, Warangal, Telangana, India
4 Associate Professor, Department of Psychiatry, Guntur Medical College, Guntur, Andhra Pradesh, India
5 Senior Resident, Department of Psychiatry, Government District Hospital, Hyderabad, Telangana, India

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Date of Submission23-Mar-2021
Date of Acceptance06-Jun-2021
Date of Web Publication09-Sep-2021
 

  Abstract 


Background: Sleep disturbances are commonly seen in mental illnesses such as schizophrenia, bipolar affective disorder, depression, anxiety, and substance use disorders. Even though psychiatric symptoms are treated, sleep disturbances remain to be persisting in some groups of patients. Persistent sleep disturbances could lead to relapse of the disorder per se or could lead to cognitive dysfunction or impairment. Depending on the severity of insomnia, cognitive impairment can vary among remitted patients.
Methodology: A total of 200 patients suffering from mental illnesses such as schizophrenia and bipolar affective disorder under remission are taken for the study. After obtaining the sociodemographic profile of the patients, insomnia severity is calculated using the Insomnia Severity Index (ISI) scale and cognitive impairment is assessed using the Montreal Cognitive Assessment (MoCA). ISI scores are compared ith MoCA scores and cognitive impairment is assessed in those patients using statistical analysis.
Results: The mean age as found to be 32.08, the mean ISI score is 20.55, and the mean MoCA score is 23.15. ISI score as negatively correlated to MoCA score and age. MoCA score as positively correlated to age.
Conclusions: Cognitive impairment, as observed on MoCA score, as more hen the insomnia severity is high and also ith increasing age. Correcting the underlying insomnia in remitted patients is very important in preventing cognitive impairment.


How to cite this URL:
Yella SA, Kumar CS, Miryala GK, Pabbathi LR, Singagari SN. A cross-sectional study of insomnia severity and cognitive dysfunction in bipolar disorder and schizophrenia patients under remission. Arch Ment Health [Epub ahead of print] [cited 2021 Nov 28]. Available from: https://www.amhonline.org/preprintarticle.asp?id=325826





  Introduction Top


Sleep disturbances are commonly seen as a comorbid condition or as part of symptomatology in various mental illnesses such as schizophrenia, bipolar affective disorder, depression, anxiety, and substance use disorders such as alcohol, cannabis, benzodiazepines, opioids, and caffeine. Even though the symptoms and psychopathology are treated, sleep disturbances are found to be persisting in some patients hich can be disabling to the patient by reducing the quality of life and also could cause cognitive impairment or dysfunction. Insomnia is a condition of unsatisfactory quantity and/or sleep quality, hich persists for a period of time. Poor sleep quality is seen in such patients. There are people ho suffer immensely from the poor quality of their sleep, hile sleep quantity is judged subjectively and/or objectively as ithin normal limits. Among people suffering from insomnia, difficulty falling asleep is the most prevalent complaint, folloed by difficulty staying asleep and early morning akening.[1] Usually, hoever, patients report a combination of these complaints. Typically, insomnia develops at a time of increased life stress and tends to be more prevalent among omen, older individuals, and psychologically disturbed and socioeconomically disadvantaged people.[1] When insomnia is repeatedly present, it can lead to increased fear of sleeplessness and a preoccupation ith its disabling consequences. This creates a vicious circle hich tends to perpetuate the individual's problem. Individuals ith insomnia describe themselves as feeling tense, anxious, orried, or depressed at bedtime. They frequently think over getting enough sleep, personal problems, health status, and even death.[1] Often, they attempt to cope ith their tension by taking medications or alcohol or other substances. In the morning, they frequently report feeling physically and mentally tired; during the day, they characteristically feel depressed, orried, tensed, and irritable.[1]

Cognitive functions could be impaired in such individuals causing mild-to-moderate differences in domains such as orking memory, attention, problem-solving, and episodic memory. Cognitive dysfunction could also be seen in remitted patients secondary to persisting sleep disturbances or due to the disorder itself or probably due to medications.[2]

In an extensive revie, Durmer and Dinges[2] in their study have reported sloing don of cognition, decrease in response time, decline in short-term recall and orking memory, and reduced learning as a result of experimentally induced sleep deprivation. They observed that mood and cognition are more impaired folloing partial than total sleep deprivation further suggesting that these specific types of sleep restriction be given special attention ithin the context of bipolar disorder (BD).

There is a considerable literature documenting cognitive deficits in BD according to a study done by Bora et al., 2009,[3] that spans several domains of neurocognitive functioning including verbal memory, verbal learning, attention, and executive functioning. These deficits have been shon to persist during periods of euthymia, leading some to conceptualize cognitive dysfunction as a core component of a specific endophenotype of BD.

A 2004 analysis of cognitive deficits in various phases of BD done by Martínez-Arán et al.[4] reported that impairments on the Wisconsin Card Sort and the Stroop ere apparent among euthymic, manic/hypomanic, and depressed patients, adding to a line of evidence suggesting that certain types of cognitive deficits may persist folloing affective recovery.

Killgore et al.[5] tested the hypothesis that higher baseline executive function may predict resiliency to cognitive deterioration folloing sleep loss. The authors recruited 54 healthy volunteers and selected the upper and loer quartiles based on performance on a vigilance task in order to gauge resiliency to fatigue. The upper quartile scored higher on a battery of executive tests (Stroop, letter fluency, and trail making), but there ere no group differences on nonexecutive tasks.

Sylvia et al.[6] conducted an investigation of sleep disturbances among 483 euthymic individuals selected from the Systematic Treatment Enhancement Program for BD. Among these individuals, 15% reported mild sleep disturbances, ith these disturbances being more prevalent in individuals ho had histories of suicide attempts as ell as hypomanic symptoms. Survival analyses revealed a significant association beteen sleep disturbances and increased risk for mood episode recurrence.

Eidelman et al.[7] conducted an analysis of sleep disturbance, illness course, and concurrent symptoms among 21 individuals ith BD in the euthymic phase. The authors found that a greater number of past depressive episodes ere associated ith more variable sleep efficiency (a basic ratio of time spent asleep vs. time spent lying in bed), as ell as a more variable total ake time.

Studying the insomnia severity is of utmost importance to assess the cognitive impairment and also differentiate beteen the cognitive impairments due to insomnia or due to disease process itself. Identifying the causes could help improve cognition by correcting or treating the underlying mechanisms. Many studies have attempted but failed to sho the causative and underlying mechanisms linking insomnia and cognitive failures. Hence, this study has been attempted and done to study insomnia severity and cognitive impairment.

Aims and objectives

  1. To study the sociodemographic profile of the patients participating in the study
  2. To estimate the severity of insomnia and its association ith cognitive impairment in patients ith mental illness
  3. To estimate the underlying factors associated ith insomnia and cognitive impairments and also compare the cognitive impairment in schizophrenia and bipolar affective disorder.



  Methodology Top


This cross-sectional, comparative study of patients ith mental illness attending a tertiary care psychiatry hospital as conducted for a period of 6 months. Both male and female patients beteen 18 and 55 years ho ere diagnosed to have schizophrenia and bipolar affective disorder and currently in remission ere taken into the study after taking ritten informed consent. Patients ith dementia, end-stage medical illness, and comorbid substance dependence ere excluded from the study.

Patients ho met the criteria of ICD-10 for schizophrenia and bipolar affective disorder ere initially selected and screened for remission using Eight-item Positive and Negative syndrome scale (PANSS) (score of <3 for 6 months) for schizophrenia and the Young Mania Rating Scale (YMRS) (score ≤8) for mania and the Mattis Dementia Rating Scale (score ≤10 for 1 eek) for depression. Finally, 100 patients ith schizophrenia and 100 patients ith bipolar affective disorder under remission ere taken into the study. Insomnia in these patients under remission as diagnosed using ICD-10 criteria. The Insomnia Severity Index (ISI) scale to assess the severity of insomnia and cognitive function as assessed using the Montreal Cognitive Assessment (MoCA) scale, and they ere correlated using SPSS softare for statistical analysis version 22. Mean and standard deviation ere obtained. Pearson correlation test as done to find out correlation.

Tools used

  1. Intake pro forma for obtaining sociodemographic data
  2. ICD-10 classification of mental and behavioral disorders, clinical descriptions, and diagnostic guidelines[1]
  3. Young Mania Rating Scale: The YMRS hich as developed by Young et al. is one of the most frequently utilized rating scales to assess manic symptoms. The scale has 11 items hich are based on the patient's subjective report of his or her clinical condition over the last 48 h. Additional information is based upon the clinical observations made during the course of the clinical intervie by the intervieer. The items are selected based upon descriptions of the core symptoms of mania. There are four questions hich are graded on a 0–8 scale hich are irritability, speech, thought content, and disruptive/aggressive behavior, hile the remaining seven items are graded on a 0–4 scale. Strengths of the YMRS include its idely accepted usage and ease of administration. The scale is generally done by a clinician or otherise trained rater ith expertise ith manic patients and takes around 15–30 min to complete[8]
  4. Montgomery–Asberg Depression Rating Scale: It as developed by Montgomery SA in 1979. The scale consists of 10 items evaluating core symptoms of depression. Nine of the items are based upon patient report, and one is on the rater's observation during the rating intervie. The items are rated on a 0–6 continuum (here 0 = no abnormality and 6 = severe). Inter-rater reliability on the MADRS ith different pairs of raters has been reported to be 0.89–0.97[9]
  5. Eight PANSS signs and symptoms scoring: The consensus group for schizophrenia importantly put forard a component of remission developed by Andreasen et al. in 2005. They recommend that for remission to be considered achieved, all eight symptoms and signs in PANSS should rate 3 or less for a period of 6 months[10]
  6. ISI: The ISI comprises 7 items and assesses the individual's insomnia over the previous 2-eek symptoms on a five-point Likert scale. The total score ranges from 0 to 28, in hich a higher score indicates greater symptom severity[11]
  7. MoCA: The MoCA is a 10-min, 30-point cognitive screening test designed to assess cognitive dysfunction and a score above 26 is considered to be normal ithout any cognitive dysfunction. The internal consistency of the MoCA as good, yielding a Cronbach's alpha on the standardized items of 0.83[12]
  8. SPSS (Statistical package for Social Sciences) softare for statistical analysis version 22. It as originally launched in 1968 by SPSS Inc., and later as acquired by IBM in 2009. It as developed by Norman H. Nie, Dale H. Bent, and C. Hadlai.



  Results Top


This study revealed many important findings hich ere significant. Statistical analysis as done for respective variables ith hich different sociodemographic parameters such as age, gender, education, religion, domicile, marital status, and diagnosis ere analyzed and tabulated. [Table 1] shos the sociodemographic variables. Our study involved mostly males (66%) than females (34%); majority ere graduates (49.5%). Most of the sample population as from urban background and also belonged to Hindu religion, as depicted in [Table 1].
Table 1: Sociodemographic data of the study subjects

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[Table 2] shos means and standard deviations for age, ISI, and MoCA scores. [Table 3] shos Pearson correlations for ISI, MoCA, and age. It implies from the table that ISI score is negatively proportional to MoCA score of the individual, i.e., the higher the insomnia severity, the loer is the MoCA score of the individual suggesting cognitive deficits. It as observed in this study that schizophrenia and bipolar disorder patients under remission, P-values for age variable as found to be insignificant. We anted to find out if there is any correlation beteen age, insomnia severity, and cognitive impairment. With insignificant P values, e found out that age is not related to insomnia severity and cognitive impairment. [Table 4] shos MoCA score for schizophrenia and BDs here majority of BD-mania patients (55) are having <26 score on MoCA. Schizophrenia patients of around 75 are having <26 score on MoCA. The results in [Table 4] indicate that majority of manic patients had higher cognitive dysfunction along ith the results of schizophrenia here majority of them had high cognitive dysfunction as indicated by MOCA scores. On studying the results obtained on MoCA, e found out that majority of the bipolar patients (63%) had impairment in short-term memory (39%) and attention, concentration, orking memory domains (24%), and other domains ere either intact or better. Many schizophrenic patients (75 out of 100%–75%) ho had lo MoCA scores had impaired short-term memory (28%), executive functions (40%), and language domain (7%) and rest of them had minor or no impairment in scores.
Table 2: Age, Insomnia Severity Index, and Montreal Cognitive Assessment score

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Table 3: Correlation beteen age, Insomnia Severity Index score, and Montreal Cognitive Assessment score

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Table 4: Montreal Cognitive Assessment score in bipolar affective disorder and schizophrenia

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  Discussion Top


This study as aimed to study cognitive functions, insomnia severity, and their correlation in remitted patients of schizophrenia and BD. There as no significant difference in insomnia severity beteen schizophrenic and bipolar patients in our study. It goes in accordance ith the study done by Laskemoen et al.[13] here no significant difference as found beteen the to groups. In the study done by Laskemoen et al., sleep disturbances ere compared ith the healthy groups as ell here a significant mean difference as found beteen the schizophrenic/bipolar group and healthy controls group.

In our study, a significant association beteen insomnia and cognitive functions as found ith significant P < 0.05. Our study goes in accordance ith the study done by Laskemoen et al.[13] here a significant association as found beteen insomnia severity and cognitive functions. In their study, the relationship beteen insomnia and each independent cognitive domain as analyzed further and compared ith healthy controls here no association as found in healthy controls.

In our study, there as no significant mean difference for cognitive functions beteen schizophrenia and BD patients. This is contradictory to the findings in the study done by Konstantakopoulos et al.[14] here schizophrenics had higher cognitive dysfunctions hen compared to bipolar patients ith a statistical significance. This variance may be due to poor educational status of the patients attending government hospitals leading to poor drug compliance and frequent relapses and recurrences leading to further deterioration of cognitive functions among BD patients in our study sample.

Fortier-Brochu and Morin in 2014[15] studied cognitive impairment in insomnia in 25 individuals ith primary insomnia and 16 controls and found alterations in attention and episodic memory, hereas in our study, e studied insomnia in schizophrenia and bipolar patients of 200 samples and found cognitive impairment in insomniacs.

Fortier-Brochu et al. in 2012[16] in their meta-analysis done in patients of insomnia and ho their cognitive performances are affected during daytime found out that individuals ith insomnia exhibit performance impairments for several cognitive functions, including orking memory, episodic memory, and some aspects of executive functioning.

Fortier-Brochu et al. in 2010[17] studied relations beteen sleep, fatigue, and quality of life in 160 chronic patients and found that insomnia itself did not impair their quality of life, herein our study did not assess or compare ith quality of life in chronic patients.

Drummond et al. in 2013[18] studied the neural correlates of primary insomniacs and their orking memory performance. They studied and compared the orking memory performances in 25 primary insomniacs and 25 generalized insomniacs and observed that primary insomniacs had reduced activation of task-related orking memory regions. Our study did not study the neural correlates and orking performances per se but has studied cognitive functions and compared ith insomnia severity in mentally ill patients ith the help of MoCA and ISI.

An analysis of cognitive deficits in various phases of BD done by Martínez-Arán et al., 2004,[19] reported that impairments on the Wisconsin Card Sort and the Stroop ere apparent among euthymic, manic/hypomanic, and depressed patients, adding to a line of evidence suggesting that certain types of cognitive deficits may persist folloing affective recovery. Our study observed that cognitive deficits ere apparently present in BD patients ho ere having high insomnia severity.

A study of euthymic bipolar patients and controls done by Cavanagh et al. in 2002[20] found that the only significant differences observed ere in tests of verbal learning/memory, namely the California Verbal Learning Test (CVLT). Our study did not perform CVLT, but cognitive functions ere assessed by MoCA test.

In an analysis of 16 individuals ith primary insomnia and 16 healthy controls, Szelenberger and Niemceicz in 2000[21] found that the degree of learning impairment on a test of immediate recall correlated ith participants' scores on the Athens Insomnia Scale. Cognitive deficits in their samples appeared to be unrelated to self-reported levels of daytime sleepiness. In our study, patients of bipolar and schizophrenia have reported daytime sleepiness ho had higher rates of insomnia severity remained to have higher cognitive dysfunctions.

Ferrier et al. 1999[22] in their study shoed that patients ere impaired on a range of neuropsychological tests but that after covarying for affective symptoms, only specific executive function, especially orking memory tests, as significantly impaired in remission. In our study too, patients shoed impaired cognitive functions in various areas such as orking memory and attention, hich ere related to insomnia severity.

Rubinsztein et al. in 2000[23] have observed in their studies that patients ith mania and unipolar depression sho generalized impairment on tests of memory and executive function. Their study demonstrated that remitted patients sho relatively specific impairment in memory ith recovery of accuracy measures on executive function task. It is similar to the findings in our study, but e have demonstrated and correlated impairment in cognitive functions ith that of insomnia severity.


  Conclusions Top


Insomnia severity is related to cognitive dysfunctions in schizophrenia and BD patients ho are under remission. We conclude according to the observations in our study that the higher the insomnia severity, the more is the cognitive dysfunction. Insomnia has been identified to cause relapses as ell as deterioration in cognitive functions in patients suffering from mental illnesses. Domains of cognition that ere mainly impaired due to insomnia or other causes ere short-term memory, attention, concentration, and orking memory domains. This study concluded many findings through hich e could identify the severity of insomnia causing cognitive impairment. Furthermore, patients ere on antipsychotics and mood stabilizers and some patients ere on antidepressants too, here e could not find out if the cognitive impairment caused as also due to antipsychotics and other medications. Further research is needed to observe this association. We could observe that correcting sleep disturbances in patients ith mental illnesses is of utmost importance and it could prevent cognitive dysfunctions if identified at the earliest.

Limitations

A single tertiary care hospital as taken for place of study. Involving other mental illnesses ould have provided a larger scale of identification of at-risk patients. Patients on antipsychotics and mood stabilizers ere involved in the study, the long-term usage of hich could be associated ith cognitive dysfunction. Our study could not find out or differentiate its association.

Further research

We aim to further plan our area of research involving other kinds of mental illnesses also. We ould also plan to extend our research involving neurological imaging and correlating ith functional areas in insomnia patients ith higher cognitive dysfunctions.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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World Health Organization. ICD-10 Classification of Mental and Behavioral Disorders, Clinical Descriptions and Diagnostic Guideline.Geneva: WHO;1992;143.  Back to cited text no. 1
    
2.
Durmer JS, Dinges DF. Neurocognitive consequences of sleep deprivation. Semin Neurol 2005;25:117-29.  Back to cited text no. 2
    
3.
Bora E, Yucel M, Pantelis C. Cognitive endophenotypes of bipolar disorder: A meta-analysis of neuropsychological deficits in euthymic patients and their first-degree relatives. J Affect Disord 2009;113:1-20.  Back to cited text no. 3
    
4.
Martínez-Arán A, Vieta E, Reinares M, Colom F, Torrent C, Sánchez-Moreno J, et al. Cognitive function across manic or hypomanic, depressed, and euthymic states in bipolar disorder. Am J Psychiatry 2004;161:262-70.  Back to cited text no. 4
    
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Sylvia LG, Dupuy JM, Ostacher MJ, Coperthait CM, Hay AC, Sachs GS, et al. Sleep disturbance in euthymic bipolar patients. Journal of psychopharmacology. 2012;26:1108-12.  Back to cited text no. 6
    
7.
Eidelman P, Talbot LS, Gruber J, Hairston I, Harvey AG. Sleep architecture as correlate and predictor of symptoms and impairment in inter-episode bipolar disorder: Taking on the challenge of medication effects. J Sleep Res 2010;19:516-24.  Back to cited text no. 7
    
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13.
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14.
Konstantakopoulos G, Ioannidi N, Typaldou M, Sakkas D, Oulis P. Clinical and cognitive factors affecting psychosocial functioning in remitted patients ith bipolar disorder. Psychiatriki 2016;27:182-91.  Back to cited text no. 14
    
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19.
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20.
Cavanagh JT, Van Beck M, Muir W, Blackood DH. Case-control study of neurocognitive function in euthymic patients ith bipolar disorder: An association ith mania. Br J Psychiatry 2002;180:320-6.  Back to cited text no. 20
    
21.
Szelenberger W, Niemceicz S. Severity of insomnia correlates ith cognitive impairment. Acta Neurobiol Exp (Wars) 2000;60:373.  Back to cited text no. 21
    
22.
Ferrier IN, Stanton BR, Kelly TP, Scott J. Neuropsychological function in euthymic patients ith bipolar disorder. Br J Psychiatry 1999;175:246-51.  Back to cited text no. 22
    
23.
Rubinsztein JS, Michael A, Paykel ES, Sahakian BJ. Cognitive impairment in remission in bipolar affective disorder. Psychol Med 2000;30:1025-36.  Back to cited text no. 23
    

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Correspondence Address:
Gireesh Kumar Miryala,
Department of Psychiatry, Kakathiya Medical College, Warangal, Telangana
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/amh.amh_34_21




 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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