One of the common symptoms of dementia is delusions. Due to a biological conceptualization of the behaviors represented as delusions, these are classified as psychotic symptoms. This is a qualitative and quantitative study aiming to describe the delusions experienced by older persons with dementia and the context of occurrence, and to elucidate their etiology. Participants were 74 nursing home residents aged 65 and over, diagnosed with dementia, from nine nursing homes in Israel. Participants with delusions were found to have significantly more difficulties in performing ADLs, and poorer vision and hearing. Based on assessment using the BEHAVE-AD, six categories of delusions were examined: 1. One's house is not one's home, 2. Theft, 3. Danger, 4. Abandonment, 5. Misidentification, and 6. Other non-paranoid. Common themes appeared across delusions including reality, disorientation, re-experience of past events, loneliness and insecurity, boredom, and trigger. Current results suggest that delusions may not represent psychotic symptoms for most participants, because they sometimes represented reality, or were neither firm nor incontrovertible. Thus, utilizing the term delusion relegates the person's behavior to the domain of severe psychiatric phenomena and precludes understanding its true meaning.
DSM-IV (American Psychiatric Association, 2000) defines a delusion as a false belief, based on incorrect inference about an external reality, that is firmly sustained despite what almost everyone believes and despite evidence constituting incontrovertible and obvious proof to the contrary. Types of delusions associated with dementia include the ‘one's house is not one's home’ delusion, delusions of theft, delusions of abandonment, delusions of danger, delusions of misidentification, delusions of infidelity, and non-paranoid delusions (Fischer et al., 2004).
Study limitations and inconsistencies in the definitions and classifications of delusions in dementia have led to inconclusive results regarding the frequency of experiencing delusions in dementia, and its prevalence over time. Past research reveals that 10%–73% of individuals with Alzheimer's Disease (AD) suffer from delusions (Wragg and Jeste, 1989, Wilson et al., 2000, Scarmeas et al., 2005 and Fernandez et al., 2010). While rates of subtypes of delusions among persons with dementia vary across studies, most studies found delusions of theft to be most common, followed by the delusion that ‘one's house is not one's home,’ and delusions of suspicion (see Table 1) (Reisberg et al., 1987, Burns et al., 1990, Deutsch et al., 1991, Khandelwal et al., 1992, Rubin, 1992, Migliorelli et al., 1995, Gormley et al., 1998 and Shaji et al., 2009).
Table 1.
Prevalence of specific delusions across studies.
Source Dementia status Sample size Sample type Overall delusions (%) Paranoid (general) (%) Theft (%) 'One's house is not one's home' (%) Suspiciousness (%) Abandonment (%)
Burns et al. (1990) AD 178 OS, IS, CS 15.7 * 9 a * 5.6 a *
Cohen-Mansfield et al. this study Dementia 74 IS 46 * 22 a 7 a * 5 a
Deutsch et al. (1991) Prob. AD 181 CS 41a 29.8 a * 14.4 a * *
Gormley et al. (1998) Prob. AD 70 CS, OS, IS 34.3a * 4.3 a * 7.1a *
Khandelwal et al. (1992) Dementia 30 CS 48 * 27 a 10a 33 a 10a
Migliorelli et al. (1995) Prob. AD 103 OS 20 * 14.6 a 5.8 a * 6-8 a
Reisberg et al. (1987) AD 57 OS * 12 a 28 a 12 a 12 a 12 a
Rubin (1992) AD 110 IS * 31 a 26 a * 9 a *
Shaji et al. (2009) DAT 40 OS, PH 53 * 30 a 35a 5 a 5 a
* Not available for this study.
Note: numbers may not add up because of overlaps, i.e., some persons manifested more than one delusion.
CS – Community Sample, IS – Institutional Sample, OS – Outpatient Sample, PH- Psychiatric Hospital
Prob – probable, AD – Alzheimer's Disease, DAT – Dementia of Alzheimer's Type.
a out of total sample.
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Various types of explanations have been proposed concerning the etiology of delusions in dementia (Cummings and Victoroff, 1990, Ballard and Oyebode, 1995, Rao and Lyketsos, 1998 and Cohen-Mansfield, 2003). Essentially, these reflect three categories: (1) Delusions may evolve from brain damage, caused by dementia; (2) Delusions may evolve from the person's response to the environment, which is restricted by the impairments caused by dementia; and (3) Delusions may reflect a separate disorder unrelated to dementia.
Prior research was confined to describing the prevalence of delusions in dementia and their subtypes using a variety of assessments, or to correlating delusions to demographic and medical data. Yet, previous studies focused on a biological conceptualization of the behaviors represented as delusions and thus failed to examine the potential influence of psychosocial and environmental factors on the presentation of delusional symptoms in this population. Thus, this study aims to describe the delusions experienced by older persons with dementia and the context of occurrence, and to elucidate their etiology.
