Gupta et al. (2008) (%)
Grover et al. (2011a) N = 151 (CLP) (%)
Grover et al. (2012b) N = 109 elderly (CLP) (%)
Jain et al. (2011) N = 85 (CLP) (%)
Mattoo et al. (2012) N = 100 (CLP) (%)
Aarya et al. (2013) N = 64 (CLP) (%)
Grover et al. (2012c) N = 30 (CAP-CLP) (%)
Grover et al. (2013a) Adult N = 245 (%)
Grover et al. (2013a) Elderly N = 76 (%)
Grover et al. (2013d) AWD N = 112 (%)
Lahariya (2012) N = 81 (CCU) (%)
Sharma et al. (unpublished) N = 75
Indian studies range (%)
Sleep–wake cycle disturbances
92–97
100
97.2
100
99
100
96.7
98.8
96.1
100
100
94.7
94.7–100
Perceptual disturbance
50–63
76.2
78.9
76.7
35
84.4
80
79.2
80.3
75
70
5.3
5.3–80.3
Delusions
21–31
27.8
35.8
37.2
14
67.2
33.3
46.5
40.8
48.2
22
0
14–67.2
Lability of affect
43–86
77.5
62.4
59.3
94
92.2
90
87.8
78.9
87
100
73.3
59.3–100
Language
57–67
76.8
79.8
73.3
90
93.8
73.3
88.2
85.8
85.7
59
90.6
59–90.6
Thought process abnormality
54–79
69.5
74.3
89.5
92
73.4
73.3
87.3
76.3
87
90
100
69.5–100
Motor agitation
24–94
94
89.0
89.5
94
85.9
93.3
90.2
90.8
94.6
73
46.6
73–94.6
Motor retardation
39.1
32.1
31.4
9
56.2
33.3
51.0
50.0
25
40
53.3
25–56.2
Disorientation
76–96
100
95.4
100
100
100
100
99.2
97.4
99.1
94
81.3
81.3–100
Attention deficits
97–100
100
97.2
97.7
100
100
100
99.6
100
100
100
100
97.2–100
Short-term memory
88–96
97.4
91.8
97.7
91
96.9
93.3
94.7
98.7
92.9
100
73.3
73.3–100
Long-term memory
93.4
65.1
40.7
97
48.4
53.3
53.1
51.3
65.2
86
57.3
40.7–97
Visuospatial ability
96.7
63.3
98.8
93
75
60
64.9
57.9
68.8
66
58.6
58.6–98.8
Phenomenology in special populations: Very few studies from the West have evaluated delirium in children and adolescents (Hatherill and Flisher 2010). Two studies from India have evaluated the clinical profile of delirium in children and adolescents. One of these was a retrospective study which included patients seen by the CL psychiatry team and reported that sleep–wake cycle disturbance, impairment in orientation, attention, short-term memory, and agitation are the common symptoms of delirium in children and adolescents (Grover et al. 2009b). In another study, authors rated 30 children and adolescents (age 8–18 years) diagnosed with delirium on DRS-R-98 and showed that delirium commonly manifests in children and adolescents in the form disturbance in attention, orientation, sleep–wake cycle disturbances, fluctuation of symptoms, disturbance of short-term memory, and motor agitation. Delusions and motor retardation were the least commonly observed symptoms (Grover et al. 2012b). In another retrospective study, the authors studied the clinical profile of delirium in elderly and reported that delirium in elderly commonly manifests in the form of sleep–wake cycle disturbance, disturbance in orientation, attention and short-term memory impairments, fluctuation of symptoms, temporal onset of symptoms, and a physical disorder (Grover et al. 2012a).
Comparison of symptoms across different age groups: Occasional study from the West has compared the symptom profile of delirium across different age groups. A study that compared children and adolescents with adults showed that compared to adults, the children and adolescent had higher average scores for acute onset, hallucinations, delusions, psychomotor symptom, and lability of mood, but lower scores for cognitive deficits, fluctuation, and sleep–wake disturbance. Further, when compared to the elderly, the children and adolescent had higher average scores for acute onset, hallucinations, delusions, psychomotor symptoms, and lability of mood, but lower scores for cognitive deficits, fluctuation, and sleep–wake disturbance (Leentjens et al. 2008). A study from Chandigarh compared children and adolescents with adults and elderly and showed that compared to adults, children and adolescents had lower frequency of long-term memory and visuospatial disturbances, whereas, compared to the elderly, children and adolescents had higher frequency of lability of affect. In terms of severity of symptoms, children and adolescents had lower severity of sleep–wake disturbances, motor agitation, orientation, attention, short-term memory, long-term memory, and visuospatial abilities compared to the adults. When compared to the elderly group, children and adolescents had higher severity of lability of affect and lower severity of short-term memory and visuospatial abilities (Grover et al. 2012b). Another study compared symptom profile of adults and elderly in a larger sample size and reported that the prevalence and severity of various symptoms of delirium as assessed on DRS-R-98 were similar across the two age groups except for the fact that adult group had higher prevalence and severity scores for thought process abnormality and lability of affect (Grover et al. 2013a). From the above, it can be concluded that there are more similarities than differences in terms of prevalence and severity of different symptoms of delirium across different age groups. This suggests that delirium manifest similarly across all age groups.
Factor analytic studies: Factor analysis as a tool has been extensively used to delineate the phenomenology of delirium. It is thought that factor analysis can help in understanding the correlations among different symptoms (Trzepacz and Dew 1995). Studies from the West have been limited to the elderly (Camus et al. 2000; Trzepacz et al. 1998; Saravay et al. 2004; de Jonghe et al. 2005), critically ill (van der Mast 1994), or those with malignancies (Trzepacz and Dew 1995; Franco et al. 2009). Many of these studies have small sample size as a limitation (Trzepacz et al. 1998; Saravay et al. 2004; de Jonghe et al. 2005; Fann et al. 2005).
The factor analytic studies from India (Table 2) have used larger sample sizes and have mostly involved DRS-R-98; however, occasional study has carried out factor analysis of the Memorial Delirium Assessment Scale (MDAS) (Shyamsundar et al. 2009) and another study used 3 scales, i.e., DRS-R-98, MDAS, and Confusion State Evaluation (CSE) (Jain et al. 2011). A study evaluated the factor structure of Intensive Care Delirium Screening Checklist (ICDSC) (George et al. 2011). Studies from India have more consistently showed 3-factor structure (except 2 studies), with minor differences across the composition of symptoms across different factors. In most of these studies, the cognitive symptoms cluster together, the motoric and psychotic symptoms cluster together, and the third factor consists of language, thought process abnormality, and diagnostic items. In general, the motoric and psychotic symptoms factor appears to be more consistent across different studies. However, it is important to remember that most of these studies have included patients with heterogenous etiologies for delirium.
Table 2
Factor analytic studies of delirium from India
Sample size | Treatment setting | Scales used | Percentage of variance explained (%) | Factor structure | |
|---|---|---|---|---|---|
Shyamsundar et al. (2009) | 120 | ICU | MDAS | 62.7 | Factor I (‘ cognitive disturbance ’)—impaired digit span, short-term memory impairment, disorientation, and inattention |
Factor II (‘ behavioral abnormality ’)—altered psychomotor activity, perceptual disturbances, delusions, disorganized thinking, sleep–wake cycle disturbances, and reduced awareness | |||||
George et al. (2011) | 53 | ICU | ICDSC | 56.2 | Factor I (altered sensorium/psychopathology)—altered level of consciousness, inattention, disorientation, hallucination/delusion/psychosis, psychomotor agitation, and inappropriate speech or mood |
Factor II (sleep–wake cycle problems)—sleep–wake cycle disturbances, and fluctuation of symptoms | |||||
Jain et al. (2011) | 86 | CLP | DRS-R-98 separately and DRS-R-98, MDAS, CSE combined | 47.8 | Factor I (‘ cognitive ’)—abnormalities of language, thought process, orientation, attention, short-term memory, long-term memory, visuospatial ability, reduced level of consciousness (awareness), and perseveration or prolonged latency |
Factor II (‘ behavioral ’)—sleep–wake cycle disturbances, delusions, perceptual disturbances including hallucinations, motor agitation, inverse of motor retardation, lability of affect, distractibility, irritability, and temporal onset of symptoms | |||||
Grover et al. (2011a) | 151 | CLP, drug naive | DRS-R-98 | 47.32 | Factor I (cognitive)—attention, orientation, short-term memory, long-term memory, and visuospatial ability |
Factor II (sleep and motoric disturbances)—sleep–wake cycle disturbances, delusions, perceptual disturbances, lability of affect, motor agitation, and inverse of motor retardation | |||||
Factor III (thought, language, and fluctuations)—language, thought process abnormality, temporal onset of symptoms, and fluctuations | |||||
Grover et al. (2012b) | 112 | CLP, elderly | DRS-R-98 | 43.5 | Factor I (cognitive)—thought disturbance, short-term memory, long-term memory, and visuospatial disturbance |
Factor II (cognitive and diagnostic factor)—disturbance of attention and concentration and the three items of diagnostic significance (temporal onset, fluctuation, and presence of physical disorder) | |||||
Factor III (psychotic and motoric symptoms)—perceptual disturbances, delusions, and the motoric disturbances | |||||
Mattoo et al. (2012) | 100 | CLP, mixed adult and elderly | DRS-R-98 | 48.5 | 2-factor model |
Factor I (cognition and thinking)—delusions, language disturbances, thought process abnormality, attention, orientation, short-term memory, long-term memory, visuospatial ability, and temporal onset of symptoms | |||||
Factor I (circadian)—motoric disturbances, fluctuations | |||||
59 | 3-factor model | ||||
Factor I (cognition)—attention, orientation, short-term memory, long-term memory, visuospatial ability, and fluctuation | |||||
Factor II (circadian and psychosis)—sleep disturbances, delusions, hallucinations, and motoric disturbances | |||||
Factor III (higher order thinking)—language disturbances, thought process abnormality, and temporal onset of symptoms | |||||
Grover et al. (2013a) | 321 | CLP, mixed adult and elderly | DRS-R-98 | 45.8 | Factor I (psychotic and motoric disturbances)—sleep–wake cycle disturbances, delusions, perceptual disturbances, lability of affect, motor agitation, inverse of motor retardation, and fluctuation |
Factor II (cognitive)—language, thought process abnormality, short-term memory, long-term memory, and visuospatial ability | |||||
Factor III (diagnostic factor)—attention, orientation, temporal onset of symptoms, and physical disorder | |||||
Grover et al. (2013a) | 245 | CLP, adult | DRS-R-98 | 46.75 | Factor I (psychotic and motoric disturbances)—sleep–wake cycle disturbances, delusions, perceptual disturbances, lability of affect, motor agitation, inverse of motor retardation, and fluctuation |
Factor II (cognitive)—language, thought process abnormality, short-term memory, long-term memory, and visuospatial ability | |||||
Factor III (diagnostic factor)—attention, orientation, temporal onset of symptoms, and physical disorder | |||||
Grover et al. (2013a) | 76 | CLP, elderly | DRS-R-98 | 48.53 | Factor I (cognitive-1)—delusions, language disturbance, thought process abnormality, long-term memory, and visuospatial ability |
Factor II (psychotic and motoric disturbances)—sleep–wake cycle disturbances, perceptual disturbances, motor agitation, inverse of motor retardation, fluctuation, and physical disorder | |||||
Factor III (cognitive-2)—inverse of lability of affect, attention, orientation, short-term memory, and temporal onset of symptoms | |||||
Sharma et al. (Unpublished) | 75 | RICU | DRS-R-98 | 54.6–63.4 | Factor I (cognitive factor)—attention, orientation, short-term memory, long-term memory, and visuospatial ability |
Factor II (motoric disturbances)—motor agitation, inverse of motor retardation, and lability of affect | |||||
Factor III (behavioral disturbances)—language disturbance, thought process abnormality, temporal onset of symptoms, and fluctuation |
Relationship between cognitive and non-cognitive symptoms: Very few studies from West have evaluated the relationship between cognitive and non-cognitive symptoms and motoric subtypes of delirium. Meagher et al. (2007) reported that among the cognitive symptoms of delirium, inattention was the most frequent and disorientation the least frequent. About one-fourth of subjects had no evidence of disorientation on the DRS-R-98, and only half had evidence of a greater than mild disturbance of orientation on the Cognitive Test for Delirium (CTD). The authors concluded that use of disorientation as a key indicator of delirium may lead to missed cases, and the use of inattention would be a more reliable way of screening cases for suspected delirium. They also reported that poor performance on attention and vigilance items on CTD was significantly related to the degree of disturbance on all other cognitive items on both the CTD and DRS-R-98, though much less so for non-cognitive items. The level of functioning on the CTD comprehension item (comprising a combination of language and executive function) was associated with more non-cognitive DRS-R-98 items than the other CTD items. Among the non-cognitive symptoms, neither delusions nor hallucinations were associated with cognitive impairments. The authors did not find any relationship between psychotic symptoms and motoric items, highlighting the fact that patients with quieter presentations also experience disturbing psychotic symptoms. Another prospective study of stem cell transplantation patients found that non-cognitive features dominated in the early stages of delirium, while cognitive impairment peaked after 1 week and dominated thereafter (Fann et al. 2005). Grassi et al. (2001) evaluated subjects with delirium on MMSE, DRS, and MDAS scale and reported high correlations between individual MDAS items and the MMSE total score than individual DRS items and the MMSE score. Non-cognitive items (e.g., perceptual disturbances, sleep–wake cycle disturbances) of both scales and certain specific DRS items (i.e., lability of mood, physical disorder) showed lower correlations with the MMSE.
A study from PGIMER, Chandigarh, evaluated the relationship of cognitive and non-cognitive symptoms of delirium as assessed on DRS-R-98 and CTD in 64 patients seen by the consultation liaison psychiatry services (Aarya et al. 2013). This study showed that poor attention on DRS-R-98 is associated with significantly higher motor retardation and higher DRS-R-98 severity scores. On CTD, higher attention deficits were associated with higher dysfunction on all other domains of CTD. Further, the study showed significant correlations between individual cognitive domains as assessed on CTD and total DRS-R-98 score (except for vigilance), DRS-R-98 severity score and DRS-R-98 severity score without the attention item score. Significant correlations also emerged between the total CTD scores and DRS-R-98 total scores, DRS-R-98 severity scores, DRS-R-98 severity score minus attention scores, total score of cognitive items of DRS-R-98, and total score of non-cognitive items DRS-R-98. Further, all these correlations persisted even when total CTD scores minus attention deficits score was used for correlations. On the basis of the findings of this study, it can be concluded that with the increase in severity of delirium, there is increase in cognitive deficits. This relationship is not dependent on attention deficits alone. Additionally, the relationship between severity of delirium exists with each domain of cognitive function (Aarya et al. 2013).
5 Subtypes of Delirium
Several attempts have been made to subclassify delirium based on phenomenological or etiological differences. Candidates for subtyping delirium include hyperactive versus hypoactive, cortical versus subcortical, anterior versus posterior cortical, right versus left hemisphere, psychotic versus non-psychotic, acute versus chronic, etc. (Meagher 2009). The most commonly used classification of subtypes of delirium is the one proposed by Lipowski (1983). Lipowski (1989) suggested ‘hyperactive’ and ‘hypoactive’ as labels for delirium subtypes, before adding a third ‘mixed’ category in recognition that many patients experience elements of both within short time frames (Lipowski 1989). Later, some of the authors have added another subtype to the above three subtypes. Liptzin and Levkoff (1992) described hyperactive, hypoactive, mixed, and neither subtype of delirium. O’Keefe and Lavan (1997) described hyperactive, hypoactive, mixed, and no subtype of delirium.
In view of the above described subtypes, studies from the West have used the descriptions of agitation and retardation from the MDAS, the Delirium Rating Scale, the Delirium Rating Scale-Revised-98, or visual analog scales, clinical observation, and agitation/sedation scale ratings to define motor subtypes.
Prevalence of various subtypes: Studies that have tried to characterize the subtype of delirium suggest that hyperactive delirium is the most common subtype in patients seen in CL psychiatry services (Mittal et al. 2006). In contrast, studies done in various other treatment settings suggest that mixed or hypoactive subtypes are more common compared to hyperactive subtype (Stagno et al. 2004). Studies that have evaluated subtypes of delirium using Delirium Motor Subtype Scale (DMSS) in palliative care setting suggest that hypoactive delirium is the most common subtype of delirium (Meagher et al. 2012, 2011). It has been suggested that some of the differences in incidence and clinical profile of motor subtypes can be attributed to assessment methods and population studied. Meagher et al. (2008) highlighted the inconsistency of current approaches by reporting concordance of motor subtype attribution with four different approaches applied to a single population as being a mere 34 %. Following this, Meagher et al. (2008) collated 30 clinical features used in different subtyping methods to define motor subtypes and developed a Delirium Motoric Checklist (DMC). Next, they identified 11 items that by virtue of frequency, correlation with independent measures of motor behavior, and relative specificity for delirium and constructed the DMSS (Meagher et al. 2008), which can be rated by both medical and non-medical staff and has been shown to have good concurrent and predictive validity (Leonard et al. 2003; Godfrey et al. 2010).
In contrast to the studies from the West, most of the studies from India have used DMSS to study the prevalence of various motoric subtypes of delirium. In a small sample study, Aarya et al. (2013) classified 64 patients of delirium using DMSS and reported nearly equal prevalence of hyperactive (39.1 %) and hypoactive delirium 35.93 %. One-eighth (12.5 %) of patients had mixed subtype of delirium, and 11 % of patients could not be classified into any of the three motoric subtypes. Sharma et al. (2012) subtyped patients of delirium admitted to RICU using RASS scores as suggested by Peterson et al. (2006) and reported hypoactive delirium (45.33 %) to be the most common subtype, followed by hyperactive (37.33 %) subtype, and only a small proportion (17.33 %) of patients were found to have mixed subtype. In the study which evaluated patients admitted to CCU for delirium, based on the DMSS, hyperactive (56.8 %) was the most common subtype of delirium, followed by hypoactive subtype (26 %). Only about 10 % of patients were categorized into mixed subtype, and 5 % could be categorized into any of the 3 subtypes and were defined as ‘no subtype.’ On further analysis, it was seen that incidence cases more commonly had hyperactive delirium (70 %), with no case of mixed subtype, whereas half (51 %) of the prevalence cases were categorized into hyperactive subtype, 26 % had hypoactive delirium, 15 % had mixed subtype, and 7 % had no subtype (Lahariya 2012). Another study evaluated motor subtypes in a large sample (N = 321) seen in CL psychiatry services showed that hyperactive subtype (50.15 %) was the most common motoric subtype of delirium, followed by mixed subtype (24.61 %), hypoactive subtype (19.93 %), and ‘no subtype’ (5.3 %) being the least common (Grover et al. 2014b).
Relationship between motor subtypes with other features of delirium: Studies from West suggest that psychosis is more common in the hyperactive subtype (Sandberg et al. 1999), while others report no difference in occurrence of psychosis between hyperactive and hypoactive subtypes (Breitbart et al. 2002) and no difference in antipsychotic responsiveness between the 2 groups (Platt et al. 1994). Greater sleep–wake cycle disturbance (Gupta et al. 2005) and mood lability (Gupta et al. 2005; de Rooij et al. 2006) have been reported in hyperactive subtype, while higher prevalence of language disturbance has been reported in hypoactive patients (Gupta et al. 2005). Evidence also suggests that there is no difference in mood alteration (Sandberg et al. 1999) between the hyperactive and hypoactive subtypes. Studies have also shown that motoric subtypes share core elements of delirium with similar degrees of cognitive impairment (Koponen et al. 1989; Meagher et al. 2000; Ross et al. 1991). However, the earlier studies from the West which evaluated cognitive impairment had done so using Delirium Rating Scale, which had only one item for assessment of all the cognitive domains (O’Keeffe and Lavan 1997). Meagher et al. (2000) using DMSS reported that subjects with hypoactive delirium scored lower than the hyperactive group for delusions, mood lability, sleep–wake cycle disturbances, and variability of symptoms, but lower than the mixed group only for mood lability. However, the three groups did not differ on cognitive functions.
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