International Psychogeriatrics (2013), 25:4, 635–643 C© International Psychogeriatric Association 2012doi:10.1017/S1041610212002232

Relationship between delirium and behavioral symptomsof dementia

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Philippe Landreville,1,3 Philippe Voyer2,3 and Pierre-Hugues Carmichael31School of Psychology, Université Laval, Québec, Canada2Faculty of Nursing, Université Laval, Québec, Canada3Centre de recherche du CHU de Québec, Québec, Canada

ABSTRACT

Background: Persons with dementia frequently present behavioral and psychological symptoms as well asdelirium. However, the association between these has received little attention from researchers and currentknowledge in this area is limited. The purpose of this study was to examine the relation between delirium andbehavioral symptoms of dementia (BSD).

Methods: Participants were 155 persons with a diagnosis of dementia, 109 (70.3%) of whom were founddelirious according to the Confusion Assessment Method. BSD were assessed using the Nursing HomeBehavior Problem Scale.

Results: Participants with delirium presented significantly more BSD than participants without delirium. Morespecifically, they presented more wandering/trying to leave, sleep problems, and irrational behavior aftercontrolling for cognitive problems and use of antipsychotics and benzodiazepines. Most relationships betweenparticipant characteristics and BSD did not differ according to the presence or absence of delirium, but somevariables, notably sleep problems, were more strongly associated to BSD in persons with delirium.

Conclusions: Although correlates of BSD in persons with delirium superimposed on dementia are generallysimilar to those in persons with dementia alone, delirium is associated with a higher level of BSD. Results of thisstudy have practical implications for the detection of delirium superimposed on dementia, the managementof behavioral disturbances in patients with delirium, and caregiver burden.

Key words: delirium, behavioral and psychological symptoms of dementia, dementia

Introduction

Persons with dementia frequently present beha-vioral and psychological symptoms that reducetheir quality of life, make care more difficultto provide, and contribute to caregiver burden.The umbrella term “behavioral and psychologicalsymptoms of dementia” (BPSD) was originallyadopted by participants of a consensus conferenceorganized by the International PsychogeriatricsAssociation in 1996. BPSD were defined as signsand symptoms of disturbed perception, thoughtcontent, mood, or behavior that frequently occur inpatients with dementia (Finkel et al., 1996). BPSDare in fact comprised of two main subgroups. Inthis study, we focus on behavioral symptoms ofdementia (BSD), which include various observable

Correspondence should be addressed to: Philippe Landreville, PhD, Schoolof psychology, Université Laval, Pavillon Félix-Antoine-Savard, 2325 ruedes Bibliothèques, Québec, QC, G1V 0A6, Canada. Phone: +418-656-2131 (3024); Fax: +418-656-3646. Email: philippe.landreville@psy.ulaval.ca.Received 15 Aug 2012; revision requested 8 Oct 2012; revised version received20 Nov 2012; accepted 20 Nov 2012. First published online 20 December2012.

manifestations such as screaming, hitting, resistingcare, wandering, sexual disinhibition, and cursing.They differ from psychological symptoms ofdementia, such as depression and delusions, whichare usually assessed on the basis of interviewswith the patient or a relative. The prevalence ofvarious forms of BSD has been found to rangefrom 12% (disinhibition) to 63% (apathy) in acommunity setting (Aalten et al., 2005). In long-term care facilities, 85% of residents with dementiashow at least one symptom of agitation, of whichgeneral restlessness is observed most frequently(44%; Zuidema et al., 2007). BSD have beenfound to be associated with various factors includingseverity of cognitive impairment, use of certaindrugs, and sleep difficulties (Ray et al., 1992; Algaseet al., 1996; Cohen-Mansfield and Libin, 2005).Insomnia, disability, depression, pain, and genderhave also been found to be associated with BSD(Cohen-Mansfield and Libin, 2005; Lemay andLandreville, 2011).

Delirium is also frequently found in persons withdementia. The essential feature of delirium is a

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disturbance of consciousness that is accompaniedby a change in cognition that is not accounted forby dementia. The disturbance develops over a shortperiod of time and presents a fluctuating course.It is usually a consequence of a general medicalcondition, substance intoxication or withdrawal,use of a medication, or toxin exposure, or acombination of multiple factors. Associated featuresof delirium include behavior problems such asperceptual disturbances, psychomotor agitation orretardation, and altered sleep–wake cycle (Amer-ican Psychiatric Association, 2000). Risk factors ofdelirium include but are not limited to older age,severity of dementia, dehydration, malnutrition,acute illnesses (pneumonia, myocardial infarction,etc.) medication use (Fick et al., 2002; Elie et al.,2009; McCusker et al., 2012), and use of physicalrestraints (Inouye, 2006; Voyer et al., 2009; 2011).Delirium superimposed on dementia is particularlyfrequent among older persons, with prevalenceranging from 22% to 89%, and may have seriouscomplications and poor prognostic implications(Fick et al., 2002).

It has been argued that BSD may be due to anunderlying delirium and that behavioral or cognitivechanges in a patient with dementia are oftenmisattributed to diurnal variation of symptoms orto the dementia itself rather than to a superimposeddelirium (Fick et al., 2002). Conversely, behavioraldisturbances have been shown to be significant riskfactors for delirium and may contribute to thisrisk by their impact on other factors associatedwith delirium such as use of physical restraints andcertain drugs (Voyer et al., 2009; 2011).

The relation between delirium and BSD hasimportant practical implications. Persons withdementia and behavioral disturbances typicallyreceive more medication (Stevenson et al., 2010).Care of these patients is also more difficult andmore costly (Okura and Langa, 2011). If behavioralproblems are caused in part by delirium, healthcareprofessionals should be particularly vigilant toidentify and treat delirium, a transient condition,rather than use medication to control behavior, suchas atypical antipsychotics that are modestly effectiveand present serious health risks (Sink et al., 2005;Schneider et al., 2006). Also, if behavioral problemscontribute to delirium, they should be preventedor managed with safe and effective treatmentsthat do not increase the risk of delirium, such aspsychosocial interventions (O’Connor et al., 2009).Delirium superimposed on dementia may lead anindividual to refuse his medication, to eat and drinkless, to fall, to have insomnia, and so on. All ofthese may become perpetuating factors of delirium(Canadian Coalition for Seniors’ Mental Health,2006).

To date, only a few studies have compared beha-vioral and psychological symptoms of patients withdelirium superimposed on dementia with patientswith dementia alone. Cole et al. (2002) foundthat the mean number of symptoms of deliriumis higher in persons with delirium compared tothose without delirium irrespective of the presenceof dementia. They concluded that delirium appearsto be phenomenologically similar among patientswith or without dementia, although patientswith dementia tend to have more symptoms.More recently, Meagher et al. (2010) reportedthat patients with either comorbid dementia anddelirium or delirium alone present more severenon-cognitive symptoms of delirium (sleep–wakecycle disturbance, perceptual abnormality, affectivelability, thought process abnormality, and motorretardation) than patients with dementia alone.However, only thought process abnormalities andmotor agitation remained statistically significantafter correction for multiple testing.

Current knowledge in this area is limited intwo ways. First, previous studies have focusedexclusively on symptoms of delirium. BSD includea broad range of manifestations, some of whichmay not be captured by measures of deliriumbecause they are not typical manifestations ofthis disorder (e.g. aggressive behavior). Holttaet al. (2011) reported overlap between deliriumand neuropsychiatric symptoms in patients withdementia. They found that 85% of patients withboth dementia and delirium suffer from multipleneuropsychiatric symptoms, and nearly one inthree patients with such symptoms fulfill criteriafor delirium. Second, it is unknown if causes ofBSD in patients with delirium superimposed ondementia differ from those found in patients withdementia alone. Examining if the correlates ofBSD vary according to the presence or absenceof delirium would help shed some light on thisissue.

The purpose of this study was to extend thisarea of research by addressing three main questions:(1) Do persons with delirium superimposed ondementia present more BSD than persons withdementia alone? (2) Do these groups differ onspecific forms of BSD? (3) Do the correlates ofBSD vary according to the presence or absenceof delirium? To examine Question 2, we selectedand controlled for potential confounding variables(cognitive problems, and use of antipsychotics andbenzodiazepines) on the basis of their reportedrelationship with both delirium and BSD. Question3 was addressed by including the same variablesas well as others (insomnia, disability, depression,pain, and gender) that have been found previouslyto be associated with BSD.

Delirium and behavioral symptoms of dementia 637

Methods

The method has been described elsewhere (Voyeret al., 2009; 2011) and will be summarized here.

Participants’ selectionParticipants were recruited in three long-termcare facilities and one long-term care unit of alarge regional hospital. A convenience samplingprocedure was used. All residents aged 65 years andolder with a diagnosis of dementia in their medicalchart and no history of psychiatric illness (psychoticdisorders, bipolar disorders, and major depressivedisorders with psychotic features) were eligible forthe study.

Measures

DELIRIUM

The Confusion Assessment Method (CAM) is anestablished and widely used test to assist withdetection of delirium (Wei et al., 2008). Thisinstrument has been shown to be sensitive (94%to 100%) and specific (90% to 95%) comparedto the diagnosis of a psychiatrist (Inouye et al.,1990). The tool assesses the nine criteria fordelirium specified in the Diagnostic and StatisticalManual of Mental Disorders, 4th edn (AmericanPsychiatric Association, 2000), i.e. (1) acute onsetand fluctuation of symptoms over the course of theday, (2) inattention, (3) disorganized thinking, (4)altered level of consciousness, (5) disorientation, (6)memory impairment, (7) perceptual disturbances,(8) psychomotor agitation or retardation, and (9)altered sleep–wake cycle. The presence of Criteria1 and 2 plus the presence of either Criterion 3 or 4is indicative of a definite delirium. For a diagnosisof probable delirium, the first criterion changes to“acute onset or fluctuation of symptoms over thecourse of the day” and the rest of the algorithmremains the same. In the present study, residentswho met the criteria for definite or probabledelirium were defined as having delirium. In thecontext of this study, inter-rater agreement wassatisfactory: κ = 0.53 (95% CI: 0.03–1.00) for CAMdefinite delirium and κ = 0.71 (95% CI: 0.21–1.00)for CAM probable delirium.

BE H A V I O R A L SY M P T O M S OF DE M E N T I A

These were assessed using the 29-item NursingHome Behaviour Problem Scale (NHBPS; Rayet al., 1992). All but one of the items (hallucina-tions) refer to directly observable behaviors. Thisscale has shown good inter-rater reliability and ahigh level of convergent validity (Ray et al., 1992).The frequency of each behavior during the lastthree days is reported using a five-point Likert

scale ranging from 0 (never) to 4 (always). A five-factor solution explaining a total of 58% of the totalscore variance was previously identified with oursample of patients with dementia through principalcomponent analysis (Fraser et al., submitted).These factors are aggressive/uncooperative behavior(seven items, e.g. “Fights or is physically aggressive:hits, slaps, kicks, bites, spits, pushes, pulls”; “Resistscare”), sleep problems (three items, e.g. “Hasdifficulty falling asleep;” “Awakens during thenight”), wandering/trying to leave (three items,e.g. “Wanders, tries to escape or go to off-limitsplaces;” “Enters others’ rooms inappropriately”),irrational behavior (three items, e.g. “Sees or hearsthings that are not there;” “Says things that donot make sense”), and agitation (three items, e.g.“Fidgets, is unable to sit still, restless;” “Doessomething over and over, even though it does notmake sense”). Total and factor scores are obtainedby summing individual item scores and are allcontinuous variables.

COGNITIVE PR O B L E M S

Dementia severity was assessed using the HierarchicDementia Scale (HDS; Cole and Dastoor, 1987).The maximum score for the entire scale is 200points. Older adults who are cognitively intactgenerally achieve the maximum or close to themaximum number of points. The validity andreliability of the scale are well established (Ronnbergand Ericsson, 1994).

MEDICATION

Use of benzodiazepines and antipsychotics over theprevious 24-hour period was recorded.

INSOMNIA

The Insomnia Severity Index (ISI; Bastien et al.,2001) was used. Each of the seven items israted on a 0–4 scale, with higher total scoreindicative of severe insomnia. Internal consistencyand concurrent validity of this scale have beendemonstrated by Bastien et al. (2001).

COMORBIDITY

Comorbidity was assessed through a chartreview using the validated and reliable CharlsonComorbidity Index (Charlson et al., 1987). Theoverall score ranges from 0 to 37 with higher scoresindicating greater comorbidity.

DISABILITY

Functional autonomy of the resident was measuredaccording to the Functional Autonomy Measure-ment System (SMAF; Hebert et al., 1988). Thetotal score ranges from –63 to 0. The absolute value

638 P. Landreville et al.

of the total score was used; therefore, higher scoreis indicative of severe autonomy impairment. Theoriginal version of this scale has shown good test–retest and inter-rater reliability (Desrosiers et al.,1995).

PA I N

Pain was assessed using the DOLOPLUS-II (Waryand Doloplus, 1999). Each of the ten DOLOPLUS-II items (somatic complaints, protective bodypostures adopted at rest, self-protection of soreareas, expression, sleep pattern, washing and/ordressing, mobility, communication, social life,behavioral problems) is rated on a 0–3 scale withhigher scores indicative of increased difficulties dueto pain. The validity and reliability of this measurehas been supported in the literature (Zwakhalenet al., 2006).

DEPR ES S I ON

Depression was assessed using the Cornell Depres-sion Scale (Alexopoulos et al., 1988). It consists of19 items corresponding to five dimensions (mood-related signs, behavioral disturbance, physical signs,cyclic functions, ideational disturbance). In thisstudy, the assessor indicates if the symptom is 0(absent), 1 (mild to intermittent), or 2 (severe). Thescale has good test–retest reliability (r = 0.75) andexcellent internal consistency (α = 0.83; Camuset al., 1995). Inter-rater reliability and concurrentvalidity are also well established (Kørner et al.,2006).

ProcedureEach resident was observed over a seven-hourperiod by two trained research nurses, both ofwhom collected different information at differenttimes during the day. To make the most of theobservation time per resident, the nurses evaluateda maximum of three residents per day. In orderto homogenize the observation period between thedifferent recruitment sites, observations took placeduring the day shift schedule, i.e. 7:30 am to 3:30pm or 8:00 am to 4:00 pm, depending on the long-term care facility involved.

A first research nurse was responsible forassessing the presence of delirium with the CAMas well as the severity of dementia using the HDS.In order to complete the CAM, she used variousdata sources (chart, family members, nursing staff,and a baseline cognitive assessment of the residentconducted seven days prior to the evaluation ofdelirium). In addition, three structured assessmentsof symptoms of delirium had to be performedover the seven-hour observation period prior tocompleting the CAM. A second research nurse,

blinded to resident delirium status, collectedbaseline characteristics (age, sex, marital status,level of education, days since admission to facility,level of functional autonomy, and comorbidity)and medication use (previous 24 hours beforeassessment with the CAM) based on the medicalchart and direct observation. She also assessed BSD(last three days before CAM) as well as insomnia,depression, and pain (last seven days before CAM).The procedures followed were in accordance withthe ethical standards of the local committee onhuman experimentation.

Statistical analysisSAS software (version 9.2) was used for dataanalysis. Descriptive statistics, such as percentage,mean, and standard deviation, were calculatedfirst. Next, t-tests were conducted to compareparticipants with and without delirium on BSD. Inorder to control for confounding variables that mayexplain the relation between delirium and BSD, weperformed a series of multiple regression analyses ofdelirium on BSD controlling for cognitive problemsand use of antipsychotics and benzodiazepines. Inthese analyses, the parameter estimate indicates theaverage difference on BSD between the levels ofeach variable (e.g. difference between delirium andno delirium). The statistics take into account theother variables in the model.

To investigate interaction between deliriumand each covariate (cognitive problems, useof antipsychotics and benzodiazepines, insomnia,disability, depression, pain, and gender), multipleregression models were fit separately for eachcombination. Significant interaction effects betweencovariates and delirium were identified andinterpreted based on the covariate’s effect estimatefor each group. Each covariate effect estimateindicates the degree to which an increase of oneunit of a given variable is associated with a change inBSD. For example, an estimate of 3.81 for insomniain participants with delirium would mean that anincrease on a single unit on the insomnia scale isassociated with a 3.81 increase on the BSD scalein that group. Because of the exploratory nature ofthese analyses, significance level was fixed at p <

0.10. For all other tests, significance level was fixedat p < 0.05. When multiple univariate significancetests were used, p was adjusted using Bonferroni’smethod. Exact p values are reported unless p <

0.01.

Results

Of the 293 eligible residents, proxy consent wasobtained for 54.6% of them (160 residents).

Delirium and behavioral symptoms of dementia 639

Figure 1. Total behavioral symptoms of dementia.

More precisely, 41.6% of proxies did notrespond and 3.8% of them refused to give theirconsent. Following enrolment, three residents diedbefore the evaluation, one was transferred, andanother hospitalized, leaving a total sample of155 participants. Of these, 109 (70.3%) wereascertained delirious according to the CAM(definite or probable). Mean age was 86.3 (SD =6.9) and the majority were women (73.5%).Mean time since admission to facility was 2.6years (SD = 2.3). The degree of cognitiveimpairment in this population was moderate witha mean score of 91.22 (SD = 49.42) on theHDS. The majority of the residents (84%) hada high level of comorbidity (score ≥6 on theCharlson Comorbidity Index). More than two-thirds of the residents were showing significantdeterioration in their functional autonomy (score≥29 on the SMAF). Antipsychotics were used by81 participants (52.26%) and benzodiazepines wereused by 78 participants (50.32%).

Mean total BSD scores for participants withand without delirium are shown in Figure 1.It can be seen that participants with deliriumpresent significantly more BSD, p < 0.0001.Between-group comparisons for each category ofBSD are shown in Table 1. Results show thatparticipants with delirium present significantly moreof most types of BSD. The difference on sleep

problems, although not significant after adjustingusing Bonferroni’s method, is substantial and in thesame direction.

Results of the first series of multiple regressionanalyses are presented in Table 2. For totalBSD, delirium is a significant predictor and thevariance explained for the model as a whole issignificant, p < 0.0001. The importance of deliriumin explaining specific types of BSD is variable.Delirium is associated with wandering/trying toleave, sleep problems, and irrational behaviorbut not with aggressive/uncooperative behavior oragitation. Cognitive problems are associated withaggressive/uncooperative behavior and irrationalbehavior. Benzodiazepines are associated with bothaggressive/uncooperative behavior and irrationalbehavior whereas antipsychotics are associated onlywith wandering/trying to leave. Total varianceexplained by each subtype of BSD model issignificant and ranges from 7% for both sleepproblems, p = 0.01, and agitation, p = 0.01, to39% for irrational behavior, p < 0.0001.

Most multiple regression analyses on BSDusing delirium and each covariate separately didnot show significant interaction effects. Thoseinteractions that were significant are presented inTable 3. All covariates in this table show a positiveassociation with behavioral problems in the groupwith delirium. Insomnia is positively associatedwith wandering/trying to leave, sleep problems,and agitation in both groups but more stronglyin participants with delirium. Antipsychotics useis positively and more strongly associated withirrational behavior in the presence of deliriumwhile the reverse is true in the absence ofdelirium. A similar pattern is found for therelation between depression and agitation. Finally,cognitive problems are negatively and more stronglyassociated with sleep problems in the group ofparticipants without delirium.

The finding of weak association betweenantipsychotics use and BSD, shown in Table 2, isintriguing since these agents are commonly usedfor treating BSD, especially aggressive behavior.

Table 1. Specific subtypes of behavioral symptoms of dementia as a function ofdelirium

NO DELIRIUM: DELIRIUM:BE H A V IO R A L S Y M P T O M S M (SD) M (SD) p............................................................................................................................................................................................................................................

Aggressive/uncooperative behavior 2.34 (3.39) 5.21 (4.60) <0.001Wandering/trying to leave 0.28 (0.01) 1.33 (2.35) <0.001Sleep problems 0.54 (0.22) 1.06 (0.75) 0.02Irrational behavior 0.28 (0.06) 2.33 (1.96) <0.001Agitation 0.45 (1.32) 1.28 (1.74) <0.01

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Table 2. Parameter estimates for variables included in multiple regression analyses onbehavioral symptoms of dementia

P A R A M E T E R

B E H A V I O R A L S Y M P T O M S V A R I A B L E E S T I M A T E SE p..............................................................................................................................................................................................................................................................

TotalDelirium 4.87 1.64 <0.01Cognitive problems −0.03 0.01 0.05Antipsychotics 2.60 1.20 0.03Benzodiazepines 3.33 1.20 <0.01

Aggressive/uncooperative behaviorDelirium 1.27 0.93 0.17Cognitive problems −0.02 0.00 0.01Antipsychotics 0.52 0.68 0.44Benzodiazepines 1.65 0.69 0.01

Wandering/trying to leaveDelirium 1.40 0.44 <0.01Cognitive problems 0.00 0.00 0.10Antipsychotics 0.82 0.33 0.01Benzodiazepines −0.09 0.33 0.77

Sleep problemsDelirium 0.78 0.32 0.01Cognitive problems 0.00 0.00 0.11Antipsychotics 0.33 0.24 0.16Benzodiazepines 0.35 0.24 0.14

Irrational behaviorDelirium 0.87 0.33 <0.01Cognitive problems −0.01 0.00 <0.001Antipsychotics 0.37 0.24 0.13Benzodiazepines 0.72 0.24 <0.01

AgitationDelirium 0.45 0.36 0.21Cognitive problems 0.00 0.00 0.13Antipsychotics 0.10 0.26 0.70Benzodiazepines 0.39 0.26 0.14

Table 3. Significant interactions with delirium on behavioral symptoms of dementia

E FF E C T E S T I M A T E E FF E C T E S T I M A T E

BEHAVIORAL S Y M P T O M S CO V A R IA T E p DELIRIUM NO DELIRIUM...............................................................................................................................................................................................................................................................................................................

Wandering/trying to leaveInsomnia <0.01 3.81 0.36

Sleep problemsCognitive problems 0.03 0.007 −0.01Insomnia 0.03 3.01 1.41

Irrational behaviorAntipsychotics 0.08 0.77 −0.24

AgitationInsomnia 0.07 1.99 0.38Depression 0.03 0.18 −0.02

Since we had data on drug use and BSD attwo separate time points (separated by a seven-day interval), we examined if the difference inBSD between these time points was related toantipsychotics use in patients with delirium. t-

tests were performed to compare participants whoreceived antipsychotics and those who did not onthe difference in BSD between each time point.Results are shown in Table 4 and none of thecomparisons were significant.

Delirium and behavioral symptoms of dementia 641

Table 4. Behavioral symptoms of dementia inpersons with delirium superimposed on dementiaas a function of time and antipsychotics use

A N T I

PSYCHOTICS

BEHAVIORAL

SYMPTOMS No Y E S p....................................................................................................................................................

Total 0.98T1 9.96 14.57T2 9.33 13.84

Aggressive/uncooperative 0.54T1 4.75 6.51T2 4.42 5.84

Wandering/trying to leave 0.03T1 1.02 1.44T2 0.83 1.74

Sleep problems 0.93T1 0.67 1.28T2 0.75 1.31

Irrational behavior 0.17T1 1.75 2.80T2 1.90 2.67

Agitation 0.40T1 1.27 1.41T2 1.08 1.44

T1 and T2 refer to time points for the collection of data onbehavioral symptoms separated by a seven-day interval. p wasadjusted using Bonferroni’s method.

Discussion

Our results indicate that persons with deliriumin addition to dementia present significantlymore BSD than persons with dementia alone.Delirium remained significantly associated withBSD in general and with three subtypes ofBSD (wandering/trying to leave, sleep problems,and irrational behavior) even after controllingfor cognitive problems and drug use. This isconsistent with symptoms and associated featuresof delirium including disorganized thinking,perceptual disturbances, psychomotor agitation,and altered sleep–wake cycle (American PsychiatricAssociation, 2000). It is also in line with results ofprevious studies (Cole et al., 2002; Meagher et al.,2010).

It is surprising that the difference between thegroups on agitation did not remain significantbecause psychomotor agitation is a typical feature ofdelirium (American Psychiatric Association, 2000).It has been suggested that hypoactivity is morefrequent in delirium superimposed on dementia(Fick et al., 2002). On the other hand, delirium wasstill associated with wandering/trying to leave aftercontrolling for confounding variables. Although thistype of behavior can be regarded as a consequenceof the increased level of motor activity often found

in delirium, the absence of difference in agitationbetween our groups suggests that other factors maybe involved. It is also possible that disorientation,another associated feature of delirium, contributesto wandering/trying to leave. On the other hand,this behavior may increase the risk of delirium(e.g. through an increase in antipsychotics use).An alternative explanation is that the potentialor tendency to wander and leave one’s residenceis already present in persons with dementia andincreased by the presence of delirium. In any case,our results point to a very serious risk to patients’security.

This study also explored if the correlates ofBSD vary according to the presence or absence ofdelirium. In general, interaction effects were notsignificant suggesting that the variables associatedwith BSD in persons with delirium superimposed ondementia are more similar than different to those inpersons with dementia alone. However, the relationbetween BSD and some patient characteristics doesseem to vary depending on the presence or absenceof delirium. Insomnia, in particular, appears to bemore strongly associated with different forms ofBSD in persons with delirium. Despite a significantinteraction, it should be noted that there is obviouslysome redundancy between the severity of insomnia,as measured by the ISI, and the sleep problemsfactor of the NHBPS. This particular relation istherefore not very informative. Future researchshould continue to examine the issue of interactionwith delirium and consider other potentialcorrelates of BSD, such as relationships withcaregivers, which were not included in this study.

Our results also suggest that the use ofantipsychotics had no effect on BSD even whencomparing BSD rates twice separated by a one-week interval and controlling for delirium status.In other words, giving these drugs had no effecton BSD, even on aggressive behaviors. Use ofantipsychotics was however associated with slightlymore wandering/trying to leave, which can behypothesized to be the result of extrapyramidaladverse effects (Lonergan et al., 2007).

The main findings of this study have importantimplications. First, they indicate that delirium isassociated with a higher level of BSD. Cliniciansshould consider delirium as a possible contributingfactor and target for management of BSD. Inversely,they should consider that BSD is a risk factorfor delirium (Voyer et al., 2009; 2011). Second,wandering/trying to leave, sleep problems, andirrational behavior may be especially useful as signsof delirium superimposed on dementia. Third,patients with both conditions may be at increasedrisk of wandering/trying to leave and may thusrequire particular attention in order to provide them

642 P. Landreville et al.

a safe environment and prevent them from leavingtheir home by themselves. Fourth, since both BSDand delirium increase burden in those caring forpersons with dementia (Sourial et al., 2001; Milisenet al., 2004), it is likely that the increased levelof BSD in persons with delirium superimposedon dementia results in more caregiver burden.Future studies should examine this issue. If this isconfirmed, educating caregivers to detect deliriumso that persons who present this disorder receiveappropriate treatment would seem an importantstrategy to reduce both BSD and caregiver burden.

There are also limitations to this study. Onelimitation is that there are other forms of BSD andBPSD that are not captured by the NHBPS butthat could be examined in future studies. Theseinclude resistance to care, anxiety, depression,inappropriate sexual behavior, and eating disorders.Another limitation is that BSD were assessed byrecalling manifestations over a period of one week.Future work should include observational data onBSD to address the potential biases of retrospectivedata. Third, the design of the study precludes anyconclusions about causality. Behavioral problemscan be a risk factor of delirium as well as a symptomof both delirium and dementia. It would be usefulto obtain prospective data to help untangle thecomplex relationship between BSD, dementia, anddelirium. Lastly, because of the relatively smallsample size, the results of this study need to bereplicated. Future research in this area is needed toaddress these shortcomings and further understandthe relation between delirium and BSD.

Conflicts of interest

None.

Description of authors’ roles

P. Landreville wrote the paper; P. Voyer designedthe study, supervised the data collection, andassisted with writing the paper; and P.H.Carmichael was responsible for the statistical designof the study and for carrying out the statisticalanalysis.

Acknowledgments

This study was made possible by the financialsupport of the Quebec Health Research Funds,the Quebec Nursing Research Funds, and Saint-Sacrement Hospital Foundation. The authors thankLise Doucet, Christine Danjou, Sophie Dufort,

Christine Noebert, and Marie-Pierre Poulin fortheir dedicated work.

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