British Journal of Psychiatry (1990), 157, 72—76
Psychiatric Phenomena in Alzheimer's Disease. I: Disorders of Thought Content ALISTAIR BURNS, ROBIN JACOBY and RAYMOND LEVY
In a sample of 178 subjects with Alzheimer's disease, diagnosed by clinical criteria (NINCDS/ADRDA), delusions had occurred in 16% of the sample since the onset of the illness
and been present within the last 12 months in 11 %. Simple delusions of theft and suspicion were the most common types and a greater proportion of men suftered delusions of theft. Subjects with other types of delusion had relatively well preserved lateral ventricular size and basal ganglia calcification. Twenty per cent of the group had experienced persecutory ideation short of delusions since the onset of the illness. Cognitive function at entry to the study and cognitive deterioration over the succeeding 12 months was not influenced by the presence
of disorders of thought content. Alzheimer's first case (Alzheimer, 1907) was a description of a 51-year-old woman in whom focal cognitive defects were associated with delusions of jealousy and auditory hallucinations. In spite of this, non-cognitive features (psychiatric symptoms and behavioural disturbances) in Alzheimer's disease (AD) have been relatively neglected compared with those related to the cognitive deficit. The importance of these symptoms and behaviour associated with AD is threefold:
Cummings be divided
into
four
types:
simple
persecutory
neurological
deficits. He concluded
that delusions
were particularly common in disorders affecting the
limbic
and
subcortical
structures.
Cutting
(1987) used these definitions as a basis for classifying delusions in 35 patients with acute organic psychoses.
He found eight patients with simple persecutory delusions, and nine with mood-congruent delusions (equivalent to Cummings' grandiose delusions). The other 18 had delusions described as “¿complex,
(b) they may indicate subtypes of the disorder (c) neuropathological correlations in AD patients
bizarre
with and without psychiatric symptoms may
or
multiple―,
which
did
not
fit
any
of
the categories described by Cummings (1985) and were afforded a separate category. The distinction
of the so
called functional disorders.
between delusions and confabulation can be difficult to make but is of importance (Cummings et al,
It is recognised that delusions occur in association with AD. Association,
that
delusions, complex persecutory delusions, gran diose delusions, and those associated with specific
(a) the strain placed on carers is related to their presence
shed light on the neuropathology
(1985), in a review, suggested
delusions in patients with organic disease could
1987). Berrios & Brook (1985) investigated 100 patients with dementia (78 AD, 22 multi-infarct dementia, MID) and found delusions in 37. Cummings et a! (1987) found delusions in just under half
DSM-III-R (American Psychiatric 1987) has a separate category subsumed
under the main heading “¿primary degenerative dementia of the Alzheimer type―for patients with delusions, but ICD-10 (World Health Organization, 1989) appears to have neglected this aspect of symptoms. Delusions in a variety of other organic
of 30 patients with AD and 15 with MID. Studies dealing exclusively with AD have reported rates
conditions have been reported. Dewhurst et a! (1969)
for delusions
found 50% of subjects with Huntington's disease to
and 31 % (Rubin et al, 1988). These differences
be deluded, Fairweather (1947) noted delusions in
are probably related to the source of the population under study.
post-encephalitic Parkinsonism, and an association has been reported between delusions and idiopathic basal ganglia calcification (Cummings & Benson, 1983). Delusions are particularly common where temporal-lobe damage has occurred, as in temporal lobe epilepsy (Toone, 1981) and herpes encephalitis, which preferentially affects temporal structures
of 21% (Reisberg et al, 1987)
Persecutory ideation (ideas not held with de lusional intensity) have been reported in 21% of AD
patients (Reisberg et al,1987). This paper describes disorders of thought content delusions and persecutory ideation - in AD. Three further papers (this issue, pp. 76—94)deal with
disorders of perception, mood, and behaviour.
(Rennick et al, 1973). 72
PSYCHIATRIC
PHENOMENA
IN ALZHEIMER'S
Method
DISEASE
73
I
computed from the CAMCOG score. Both these scales were used because we consider the first to be
deficient in the detailed assessment of cognitive
Subjects All subjects
were drawn from the catchment
Camberwell Health Authority in south-east London. All were patients who had been in contact with the only two psychiatric hospitals in the area as out-patients, day patients, or in-patients or seen on domiciliary visits. Patients
who had been seen previously at the hospital and were in residential homes or long-stay care were also included. An attempt was made to assess all patients known to the hospital services between October 1986and October 1988. All patients satisfied the criteria for the clinical diagnosis of AD suggested by the National Institute for Neurological
andCommunicative Disordersand Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS/ ADRDA) (McKhann et a!, 1984).These criteria are the most sophisticated available for the clinical diagnosis of AD and the proportion of cases satisfying the criteria who are later found to have neuropathological changes of AD is high, between 85% (Tierney et a!, 1988) and lOO% (Martin et a!, 1987). Two main categories are defined: ‘¿probable', which
is reserved
for subjects
without
physical
illness or atypical
course
or presentation.
Patients in both these categories would satisfy criteria in DSM—III—Rfor primary degenerative dementia of the
Alzheimer type and for dementia in Alzheimer's disease in ICD-lO. The distinction between ‘¿possible' and ‘¿probable' AD is ambiguously defmed and we have taken a particularly strict view, utilising the ‘¿possible' category wheneverthere was significant
coexisting
physical disease.
in that
of non-cognitive
(c)
The Clinical Dementia Rating (CDR; Hughes et a!, 1982) assigns a rating of mild, moderate, or severe dementia. (d) Each patient underwent a computerised tomography
@cm scanoftheheadusinga GEC9800scanner.
The CT scan was assessed in two ways. (i) A visual rating of atrophy of the frontal, temporal, occipital, and parietal lobes was made on a four-point scale. Atrophy of the Sylvian fissure (both right and left) was assessed on a similar four-point scale and widening of the interhemispheric fissure measured on a three point scale. Each rating was made by comparing the scan with a standard. The presence or absence of basal ganglia calcification was also noted. (ii) Computerised measurements were made using a movable cursor on the independent viewing console of the scanner. Ventricular size (enabling
any associated
physical illness, and ‘¿possible', which allows for a diagnosis of AD to be made in the presence of atypical features such as minor
function and the latter symptoms.
area of the
a ventricular :brain ratio (VBR) to be calculated), size of the third
ventricle
and right and left
Sylvian fissures were assessed. All computerised assessments were reported as an area (cm2). The inter-rater reliability kappa for the visual ratings was 0.85. Correlations on the inter-rater and test-retest
reliability of the computerised
assessments
were 0.99 and 1.00 respectively. The VBR assessed on computer correlated with that made by planimetry (kappa = 0.98). (Detailed methods of the CT scan analysis will be published separately.)
Allpatients arepartofa longitudinal studyinvestigating(e) Each subject has been followed up and repeat the natural history of AD and correlating clinical and psychiatric and neuropsychological testing and CT neuropathological findings. scan have been performed at 12-month intervals. The results of repeat cognitive testing at 12 months and death rates up to 30 months are presented here. Assessment Each patient was examined
personally
by AB at entry to
the study. Additional information was gathered from the relativesand from nursingand othercarestaff looking after the patient. The patient's medical record was also examined. Patients were assessed using the following standardised procedures. (a) The Geriatric Mental State Schedule (GMSS; Copeland et a!, 1976), based on the Present State Examination
(PSE; Wing et a!, 1974), provided a
comprehensive assessment of current psychiatric symptoms. (b) The CAMDEX (Roth eta!, 1986)comprises various sections, including a section on cognitive assessment
(CAMCOG) and an interview schedule with an informant regarding the history of the dementing illness. The CAMCOG comprises many subsections including scales assessing memory, language and praxis. The Mini Mental State Examination(MMSE; Folstein eta!, 1975)and the AbbreviatedMentalTest Score (AMTS; Thompson & Blessed, 1987) can be
Definitions of psychiatric symptoms Delusions were defined according to Fish (1985) and Cummings (1985). Their presence required that the ideas be firmly held and impervious to evidence to the contrary. Presence or absence of delusions was based on historical evidence obtained through the history section of the CAMDEX and by taking additional evidence (e.g. from medical case records) when necessary. As the sample was weighted towards those with severe illness and patients were sometimes not seen until some time after presentation, to have considered only those with delusions at the time of the interview would have been misleading. Delusions were
recorded as present (a) if they had occurred at any time since the onset of the illness and (I,) if they had occurred within the months before entry to the study (to correspond
with the follow-upintervals).Thus (b) representsa subset of (a).
To avoid erroneously attributing symptoms to an acute delirium, delusions had to be present for at least seven days.
They were dividedintothreecategories: delusions of
74
BURNS ET AL Disorders
TABLE I of thought in Alzheimer's
ratio (M:F)°h
No. (%) with disorderSex
affectedAny
disease of men affected%
of women
delusions28(15.7)13:1535ll***Any (withinprevious recent delusions 12 months)19 (10.7)9:1024Delusions of theft16 (9.0)7:9196**Delusions (5.6)4:6114Other of suspicion.10 delusions6 (3.4)3:382Persecutory ideation36 (20.2)9:272419Any disorder of thought'53 (29.8)16:374326 1. The total number of subjectswith delusions,persecutoryideation, or both. P