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 Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 2  |  Issue : 2  |  Page : 83-89

Influence of preexisting cognitive deficits on symptom profile and motoric subtypes of delirium


Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Date of Web Publication18-Jan-2016

Correspondence Address:
Sandeep Grover
Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2348-9995.174272

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  Abstract 

Aim: To compare the symptom profile of patients with delirium without preexisting cognitive deficits and those experiencing delirium in the background of preexisting cognitive deficits.
Materials and Methods: A total of 107 patients aged ≥60 years with diagnosis of delirium as per the Diagnostic and Statistical Manual, IV text revision criteria were evaluated on Short Informant Questionnaire on Cognitive Decline in the Elderly (Short IQCODE), Delirium Rating Scale Revised 98 version (DRS-R98), amended delirium motor symptom scale, and delirium etiology checklist and risk factor checklist. On the basis of short IQCODE score, the study sample was divided into those with (≥3.5) and without cognitive deficits and were compared for the symptom profile, motor subtype, risk factors, and etiologies.
Results: Based on the short IQCODE scores, the patients were divided into those with (≥3.5) and without cognitive deficits (<3.5). Those with cognitive deficits (n = 20) were significantly older and more often had delirium prior to getting admitted to the hospital. The groups did not differ in terms of frequency and severity of various symptoms of delirium, DRS-R98 total score, DRS-R98 severity score, DRS-R98 cognitive domain score, DRS-R98 noncognitive domain score, motor subtypes, various risk factors, various associated etiologies, mean number of risk factors for delirium, and mean number of associated etiologies. There was no association between mean IQCODE score and severity scores for each symptom of delirium as per DRS-R98, DRS-R98 total score, DRS-R98 severity score, DRS-R98 cognitive domain score, and DRS-R98 noncognitive domain score.
Conclusion: There is no difference in the symptom profile of those with and without preexisting cognitive deficits.

Keywords: Cognitive deficits, delirium, symptom profile


How to cite this article:
Grover S, Chakrabarti S, Avasthi A. Influence of preexisting cognitive deficits on symptom profile and motoric subtypes of delirium. J Geriatr Ment Health 2015;2:83-9

How to cite this URL:
Grover S, Chakrabarti S, Avasthi A. Influence of preexisting cognitive deficits on symptom profile and motoric subtypes of delirium. J Geriatr Ment Health [serial online] 2015 [cited 2019 Oct 17];2:83-9. Available from: http://www.jgmh.org/text.asp?2015/2/2/83/174272


  Introduction Top


Delirium is an acute brain dysfunction, which is common, serious condition and is reported to be associated with high rate of mortality. It is more commonly seen in elderly. The presence of dementia or cognitive dysfunction is a well-known risk factor for development of delirium. Delirium superimposed on dementia (DsD) has been shown to be associated with higher rates of dependence in terms of help required for walking, institutionalization, and mortality. [1],[2] Further, it has been shown that in terms of course, DsD is associated with longer duration of delirium and slower recovery. [3]

Although many studies have evaluated the phenomenology of delirium, very few studies have evaluated the effect of preexisting cognitive deficits on the symptomatology of delirium and there is a lack of consensus. In one of the earlier studies, authors compared patients of delirium (n = 18) and those with DsD (n = 43) by using Delirium Rating Scale (DRS), Mini-Mental State Examination (MMSE), Brief Psychiatric Rating Scale (BPRS), and electroencephalographic (EEG) and showed that the two groups had no difference on DRS, BPRS, and EEG profile; however, those with DsD had lower MMSE scores. [4] A study divided the participants on the basis of scores obtained on short Informant Questionnaire on Cognitive Decline in the Elderly, short form (IQCODE) and categorized 104 participants into those without cognitive deficits and those with mild, moderate, and severe prior cognitive impairment. These patients were evaluated for the symptoms of delirium by using Short Portable Mental Status Questionnaire (SPMSQ) and Confusion Assessment Method (CAM). When compared, the authors did not find difference in the symptom profile of those with mild, moderate, or severe cognitive deficit except for disorganized thinking which was more prevalent among those with mild cognitive impairment. [5] Another study included patients with dementia only (n = 20), delirium only (n = 40), controls (n = 40), and those with DsD (n = 40) and reported that those with delirium and DsD have comparable symptom profile in terms of DRS-R98 and cognitive test for delirium (CTD). However, those with dementia and healthy controls had lower scores on both the scales. [6] It has also been shown that compared to those with delirium in the absence of dementia, those with DsD more often have past history of delirium, and are more often treated with analgesic medications. [7]

However, there are few studies which report that preexisting cognitive deficits do influence the symptom profile of delirium. A study compared the patients of delirium and DsD in palliative care set-up in terms of memorial delirium assessment scale and reported that compared to patients with delirium in the absence of preexisting cognitive deficits, those with DsD had a higher level of disturbance of consciousness and impairments in all cognitive domains (i.e., orientation, short-term memory, concentration, organization of thought process) but not for the noncognitive symptoms (i.e., hallucinations, delusions, psychomotor behavior, and sleep-wake cycle disturbance). [8] One of the recent studies reported that compared to those with delirium in the absence of cognitive deficits, those with DsD have higher severity scores on DRS-R98. [3] Accordingly, it can be said that the issue of the influence of preexisting cognitive disturbances on delirium is not yet settled, and there is a need to expand this literature. Accordingly, the present study aimed to compare the symptom profile of patients without preexisting cognitive deficits and those experiencing delirium in the background of preexisting cognitive deficits.


  Materials and Methods Top


The study was done by the psychiatry consultation-liaison (CL) team in a multispecialty tertiary care hospital. The hospital has approximately 2000 beds, with all the major medical and surgical specialties and there is a lot of cross-referral between different specialities to provide care to the patients. Psychiatry CL team, uses a three-tier system; in which any patient referred to the psychiatry CL team is the first evaluated by a Junior Resident (MD trainee resident) under the supervision of a Senior Resident (qualified psychiatrist, registrar level). After evaluation, the patient is reviewed by the consultant and on the basis of the history, mental status examination and investigation findings, psychiatric diagnoses are made as per the International Classification of Diseases, 10 th revision. A management plan is formulated and executed.

Ethical approval for the study was obtained from the Institute Ethics Committee. Written informed consent was obtained from a responsible family caregiver, accompanying the patients during the inpatient stay.

All the patients referred to CL psychiatric services, and diagnosed with delirium were eligible for this study. For inclusion, patients were required to be aged ≥60 years and must be fulfilling the diagnosis of delirium as per the Diagnostic and Statistical Manual, IV text revision (DSM-IV TR). [9] Those admitted in the intensive care units and on mechanical ventilation were excluded.

Instruments

Diagnostic and statistical manual, IV text revision criteria for delirium and depression

DSM-IV TR [9] criteria are standard criteria for making the diagnosis of delirium. Over the years, DSM-IV has been the basis of designing various screening instruments for delirium and those used to assess the severity of delirium. A qualified psychiatrist also evaluated the patients for the presence or absence of depression as per the DSM-IVTR criteria prior to development of delirium based on the information available from the caregivers staying with the patients.

Short Informant Questionnaire on Cognitive Decline in the Elderly (Retrospective)

It is a 16 item instrument, which is rated, based on the information obtained from a key relative to determine the cognitive status of the patient for the specified period (last 6 months for this study). It is considered to be relatively unaffected by education, premorbid ability, and proficiency in the language. Based on the information obtained, each item is rated on a 5-point scale with scores higher than 3 indicating a more cognitive decline. [10] The score of 3 indicates no change in cognitive status and the lower scores indicates improvement in cognitive functions. To obtain the final score, the scores obtained for all items are added and divided by 16. Many researchers have evaluated the sensitivity and specificity of short IQCODE for dementia and many cut-offs ranging from 3.31 to 3.5 have been used. [11],[12],[13] In one of the studies involving patients from primary care, a cut-off 3.2 was associated with 100% sensitivity and 76% specificity. However, when the cut-off 3.6 was used, the sensitivity was 75%, and the specificity was 98%. [12] For this study, we used a cut-off of 3.5 to categorize the sample into those with and without cognitive deficits.

Delirium rating scale revised 98 version

It comprises of 16 items, 13 of which are used for rating of severity of illness and 3 items are of diagnostic significance. First, 14 items are rating on a 4 point scale (0-3) and last two items are rated on 3 point scale (0-2). The mean severity score ranges from 0 to 39 and total score ranges from 0 to 46. It has been extensively used to study the symptom profile of delirium. It has also been shown to have high inter-rater reliability, sensitivity, and specificity. [14]

Amended delirium motor symptom scale

This scale was derived from delirium motor checklist. [15] It comprises of 13 items, 5 of which are used for the assessment of hyperactivity and 8 items are used for the assessment of hypoactivity. Each item is rated as "yes" or "no" based on the motor activity in the last 24 h. Based on the overall rating the delirium is subtyped as hyperactive, hypoactive, mixed, or no subtype. For this study, this amended delirium motor symptom scale (amended DMSS) was used for subtyping the delirium. [15],[16]

Delirium etiology checklist

The checklist consists of 12 etiological categories (drug intoxication, drug withdrawal, metabolic/endocrine disturbance, traumatic brain injury, seizures, intracranial infection, systemic infection, intracranial neoplasm, systemic neoplasm, cerebrovascular, organ insufficiency, other central nervous system disorder, and other systemic disorder), which are rated on a 5-point scale based on the degree of attribution to the delirium episode, ranging from "ruled out/not present/not relevant" (score-0) to "definite cause" (score-4) based on all the available clinical information. [17]

Risk factor checklist

Based on the review of the literature, a risk factor checklist was prepared to rate the various risk/etiological factors commonly associated with delirium.

Family members of the patients diagnosed with delirium by the CL psychiatry team were contacted and explained about the purpose of the study. Initially, the diagnosis of delirium based on the DSM-IV TR criteria was confirmed based on the information provided by the family caregivers, treating team, and mental status examination of the patient. The caregivers of patients with confirmed diagnosis of delirium were interviewed on short IQCODE to establish the level of cognitive functioning of the patient in 6 months prior to the development of symptoms of delirium. Based on the short IQCODE scores, the patients were divided into those with (≥3.5) and without cognitive deficits (<3.5). Patients were further evaluated on DRS-R98 and amended DMSS. The etiology checklist and risk factors for delirium were rated based on the history, information obtained from the caregivers, treatment records, and investigation findings.

Statistical analyses

Data were analyzed by using Statistical Package for Social Scientists version 14 (SPSS-14, Chicago, IL, USA). Mean, standard deviation, frequency, and percentages were calculated for the descriptive data. Comparisons were done by using t-test, Chi-square test, Mann-Whitney U-test, and Fischer exact test. Associations between different variables were studied by using Pearson's product moment correlation and Spearman rank correlation.


  Results Top


The study cohort was formed by 107 patients, of whom 20 were categorized as having cognitive deficits. The demographic and clinical profile of patients are shown in [Table 1]. Mean age and proportion of those with delirium before admission to the hospital were significantly more among those with cognitive deficits. There was no significant difference between the two groups in terms of years of education, gender, and duration of delirium.
Table 1: Demographic and clinical profile

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Risk factors for delirium

[Table 2] depicts the commonly present risk factors for the development of delirium. The most commonly noted risk factors were the use of more than 3 medications, use of antibiotics, use of NSAIDS, history of smoking, and anemia. When the two groups were compared in terms of risk factors, no significant difference was noted on various risk factors except for the use of restraints and the use of more than 3 medications. Use of restraints was noted more frequently among those with preexisting cognitive deficits (25% vs. 8%; Chi-square value −4.69; P = 0.03*), whereas those without preexisting cognitive deficits had significantly higher proportion of those who were receiving more than 3 medications (51.72% vs. 25%; Chi-square value −4.66; P = 0.03*).
Table 2: Risk factors for the development of delirium in study sample

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In terms of various etiological categories [Table 3], the majority of the patients had metabolic and/or endocrine disturbances as the etiological factors associated with delirium and this was followed by the presence of neoplasm and organ insufficiency. When the two groups were compared in terms of frequency of presence of associated etiologies (by combining the definite cause, likely cause, and the present and possible contributory etiological categories), no significant difference was noted.
Table 3: Delirium etiology checklist

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Symptom profile of delirium

The symptom profile of delirium in terms of frequency and the severity of symptoms is shown in [Table 4] and [Table 5]. All the patients had the presence of physical disorder and fluctuation of symptoms. Other commonly present symptoms included acute onset of symptoms, inattention, disorientation, visuospatial disturbances, thought process abnormality, disturbances in long-term, and short-term memory and language. In terms of severity of symptoms, mean scores were more than 2 for the items of sleep disturbances, acute onset of illness, motor agitation, disorientation, inattention, and short-term memory disturbances.
Table 4: Frequency of delirium symptoms on DRS-R98

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Table 5: Severity of delirium symptoms on DRS-R98

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When both the groups, i.e., those with and without cognitive deficits were compared, there was no significant difference between the two groups in terms of frequency and severity of each symptom, DRS-R98 total score, DRS-R98 severity score, DRS-R98 cognitive domain score, and DRS-R98 non-cognitive domain score.

In terms of motor subtypes, as shown in [Table 2], the majority of the patients had hyperactive subtype and when the two groups were compared no significant difference was noted between the two groups.

Association of IQCODE score and DRS-R98 scores

There was no significant association between IQCODE score and the mean scores of each item of DRS-R98, DRS-R98 total score, DRS-R98 severity score, DRS-R98 cognitive domain score, and DRS-R98 noncognitive domain score in the whole group and either of the two groups.


  Discussion Top


Very few studies have evaluated the influence of preexisting cognitive deficits on symptom profile of delirium. [4],[5],[6],[8] The present study attempted to expand the knowledge in this area. In the present study, preexisting cognitive deficits were substantiated by using the short IQCODE scale with a cut-off of ≥3.5, which is considered to have about 98% specificity in detecting dementia. In India, in substantial proportion of the patient, dementia remains undetected till the late, accordingly, to be surer about the existence of the same, we preferred to use this cut-off so as to categorize the study sample into various groups. In the present study, symptom profile of delirium was assessed by using DRS-R98, which is a more comprehensible instrument to assess the symptom profile and the motor subtyping was done by using a standardized scale. Previous studies which have compared the motor subtypes of those with and without preexisting cognitive deficits have usually not followed the same. [5]

Findings of the present study suggest that those with preexisting cognitive deficits were significantly older. This finding is quite understandable considering the known fact that the incidence of cognitive deficits/dementia increases with age. [18] Previous studies which have compared these groups have also reported similar findings. [9] Patients with preexisting cognitive deficits more often had delirium prior to being hospitalized. This finding suggests that in many cases, those with preexisting cognitive deficits are admitted late to the hospital even in the presence of medical complications.

The present study suggests that there is no significant difference between those with and without preexisting cognitive deficits in terms of frequency and severity of various symptoms of delirium, DRS-R98 total score, DRS-R98 severity score, DRS-R98 cognitive domain score, and DRS-R98 noncognitive domain score.

There is a lack of consensus in the literature in terms of the influence of preexisting cognitive deficits on symptom profile of delirium with the majority of the studies reporting a lack of difference between the groups. [3],[4],[5],[6],[7] Our findings are supported by previous studies which also did not find significant difference between those with delirium and DsD in terms of DRS, MMSE, BPRS, EEG findings, [4] DRS-R98, and CTD. [6] Another study also showed that those with different levels (mild, moderate, and severe) of preexisting cognitive deficits lack significant difference in terms of SPMSQ and CAM (which were used to assess the symptom profile of these patients), except for disorganized thinking which was more prevalent among those with mild cognitive impairment. [5] In our study too, we did not find any association of IQCODE scores with the DRS-R98 severity scores. Accordingly, it can be said that the present study and most of the available literature suggests that preexisting cognitive deficits do not have a significant influence on the symptom profile of patients with delirium.

However, findings of the present study are not supported by some of the previous studies which suggest that compared to those with delirium, those with DsD have higher severity scores on DRS-R98, [3] higher level of disturbance of consciousness and impairments in all cognitive domains (i.e., orientation, short-term memory, concentration, and organization of thought process). [8] The differences between the findings of the present study and these studies can be understood in the background of treatment setting from which the patients were recruited. One of the studies relied on patients referred to psychiatry CL services from palliative care settings, [8] whereas the other study followed screening method for evaluating delirium in the acute geriatric monitoring unit. [3] Accordingly, it can be said that the treatment setting possibly influences the findings and there is a need to evaluate this issue further.

Only one of the previous studies has reported about psychomotor subtypes, but without using a standardized scale. This study reported a lack of significant difference in the prevalence of various motoric subtypes between those with and without preexisting cognitive deficits. [5] In the present study too, there was no significant difference in the prevalence of various motoric subtypes between those with and without preexisting cognitive deficits.

Occasional studies have reported that those with DsD more often have past history of delirium and are more often treated with analgesic medications. [7] However, findings of the present study do not support the same.

The present study has some limitations. The study included a small sample size. Further, the proportion of patients with preexisting cognitive deficits were relatively low in number as compared to the whole sample size. The study was limited to the patients referred to the CL Psychiatry team and did not include those with delirium admitted in various intensive care units. Hence, the findings of the present study cannot be generalized to other treatment settings. The assessment of symptoms was cross-sectional and the patients were evaluated only once. Accordingly, the present study cannot provide information about the course of symptoms of delirium and outcome in the presence of preexisting cognitive deficits. Future studies must attempt to overcome these limitations.

To conclude, the present study suggests that there is no significant difference in the symptom profile of delirium both in terms of frequency of various symptoms and severity of symptoms among those with and without preexisting cognitive deficits. Further, there was no association between the preexisting cognitive deficits and severity of symptoms of delirium. The present study also suggests that the two groups' do not differ in terms of motoric subtypes of delirium, various risk factors, and associated etiological categories.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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