CAMCOG.pdf
Transcript of CAMCOG.pdf
-
5/28/2018 CAMCOG.pdf
1/8
CAMCOG: Detaileddescription, population dataand psychometric properties
-
5/28/2018 CAMCOG.pdf
2/8
-
5/28/2018 CAMCOG.pdf
3/8
CAMCOG: Detailed description, population dataand psychometric properties
The Cambridge Cognitive Examination (CAMCOG) is a
concise neuropsychological test for the assessment of
cognitive impairment in elderly people. It was designed
specifically to assist in the diagnosis of dementia at an
early stage. CAMCOG assesses a broad range of cogni-
tive functions, as is required for the diagnosis of demen-
tia, and it minimises floor and ceiling effects by covering
a range of item difficulty.
Aims
To assess the range of cognitive functions required
for a diagnosis of dementia.
To assist in differential diagnosis within the demen-
tias.
To incorporate items which are graded in difficulty
within a cognitive domain in order to assess the full
range of cognitive ability.
To permit the measurement of cognitive decline
from very high levels of premorbid ability by minimiz-
ing ceiling effects.
To facilitate comparison with some other widely
used brief cognitive tests, by including them within
its framework.
To examine profiles of cognitive performance by
deriving scores on subscales which assess different
cognitive abilities.
Content
The items contained in the CAMCOG were selected to
sample the areas of cognitive functioning which arespecified in operational diagnostic criteria, such as those
elaborated in DSM-IV (American Psychiatric Association,
1994) and ICD-10 (World Health Organization, 1993).
These cognitive functions include memory, language,
attention, perception, praxis and thinking (now called
executive functioning). The CAMCOG also samples
important domains within an area of cognitive function-
ing; for example, memory items include assessment of
remote and recent memory, semantic and episodic
memory, intentional and incidental learning, and recall
and recognition measures of retrieval. The CAMCOG
incorporates items which are commonly used in neu-
ropsychological assessment to examine dissociable fun-
tions. Thus, for example, there are measures of language
comprehension and language expression and these are
assessed both in an oral and in a written form. Some
standard neuropsychological items which are included in
the CAMCOG are verbal fluency, similarities and the
identification of objects photographed from unusual
views. A summary of CAMCOG items and subscales is
provided in Table 1.
All the MMSE items are included in the cognitive exami-
nation but the following are not used in calculating the
CAMCOG score; naming two objects (pencil, wrist-
watch), registration and recall of three words, writing a
sentence and paper folding. The processes involved in
these tests are assessed in more detail by other
CAMCOG items. CAMCOG also contains the
Abbreviated Mental Test (AMT) of Hodkinson (1972),
derived from the original Dementia Scale of Blessed
et al. (1968) and its predecessor (Roth & Hopkins,
1953).
CAMCOG-R differs from CAMCOG in three ways:
(1) It includes two additional items to assess executivefunction in more detail; a verbal measure (ideational
fluency) and a non-verbal measure (visual reasoning).
(2) In addition to the six original items assessing remote
memory (for the period of the 1930s and 40s), it
contains six alternative items (for the period of the
1950s and 60s) which are intended for more
recently born cohorts.
(3) The tactile perception item (recognising two coins
placed in the subjects hand) has been omitted.
This item proved problematic as new coins were
introduced and normal elderly people often had dif-
ficulty in recognising them. The omission of this item
brings the CAMCOG total down from the original
107 to the new total of 105.
Scoring
CAMCOG provides subscale scores for hypothetically
dissociable functions, as well as a total score with a
maximum of 105 points. Each item contributes between
1 and 6 points to the relevant subscale and to the total
score. For the animal fluency item, where elderly subjectsmay produce over 40 different animals, recoding is nec-
essary, as specified in question 158.
Despite the addition of further tests of executive func-
tion, the original CAMCOG scoring and total score has
-
5/28/2018 CAMCOG.pdf
4/8
82 Detailed description
not been changed, but a separate executive function
score may be calculated (see p. 66).
Extended assessment of executive function
CAMCOG takes approximately 20 minutes to adminis-
ter. Strict adherence by the interviewer to the printed
instructions for administration and coding is required to
ensure reliable scores.
Administration
Executive function is the term used to describe a variety
of high level cognitive processes including planning,
organisation, abstraction, categorization, initiation, rea-
soning, mental flexibility, sequencing and the allocation
of attentional resources. Neuropsychological evidence
suggests that the frontal lobes play a key role in perfor-
mance on tasks of executive function (e.g. Cummings,
1993) and that performance on such tasks may be com-
promised relatively early in the course of dementia.
Impaired executive function together with a relative
preservation of memory is indicative of dementia of the
frontal type (e.g. Gregory & Hodges, 1993).
Executive function is very difficult to assess briefly, both
because of the many different processes subsumed
under this rubric, and because most of the existing mea-
sures (many still at an early stage of development) tend
to be time-consuming. The original CAMCOG contains
two items which can be regarded as measures of execu-
tive function. These are the Similarities questions which
assess abstraction, and the fluency item (animals) which
assesses initiation and categorisation. In view of the
increasingly prominent role of executive function mea-
sures in cognitive assessment and dementia diagnosis
two further items have been added. The ideational
fluency item (How many different uses can you think of
Table 1 CAMCOG items and subscales
Subscale Maximum Score Sections Maximum Score
1 Orientation 10 Time 5Place 5
2 Language 30 Comprehension:motor response 4verbal response 3reading 2
Expression:naming 6fluency (animals) 6definitions 6repetition 1writing to dictation 2
3 Memory 27 Remote 6Recent 4New learning: incidental 12New learning: intertional 5
4 Attention and calculation 9 Serial sevens 5Counting backwards 2Calculation 2
5 Praxis 12 Copying 3Drawing 3
Actions to command 66 Abstract thinking 8 Similarities 87 Perception 11 Tactile recognition* 2
Visual recognition 2Unusual views 6Recognise person 1
Total 107
* This item (recognising two coins) has been omitted from CAMCOG-R, changing the total from 107 to 105.
-
5/28/2018 CAMCOG.pdf
5/8
CAM CO G: Detailed description 83
for a bottle?) is taken from a test battery developed by
Crawford et al. (1995). It assesses initiation and mental
flexibility in the verbal domain. To assess executive func-
tion in subjects who may have language problems, a
non-verbal test of visual reasoning has been added. It
uses a format somewhat similar to Ravens Progressive
Matrices (Raven et al., 1976) and assesses sequencing,
categorisation and abstraction.
The ideational fluency test has been validated in patients
with head injury, where it was found to be more sensitive
to impairment than other fluency tests (Crawford, 1995).
Validation studies are currently underway in normal
elderly and demented patients. The tests are included in
advance of published results, on the basis of their validity
in other contexts and their brevity. They are inserted after
the Similarities items (questions 197200) and num-
bered 200(a) and (b). Because of their provisional status,
scores on these tests do not contribute to the total
CAMCOG score, which remains unchanged. A separate
executive function score may be derived by adding thescores on these two items to the scores on similarities
and animal fluency (see p. 66). For this purpose, both
ideational fluency and animal fluency are recoded, bring-
ing the maximum executive function score to 28.
CAMCOG Applications
CAMCOG has been used in many published investiga-
tions both clinical (e.g. Hunter et al., 1989; Jobst et al.,
1992a, b) and population-based (e.g. OConnor et al.,
1989; Brayne & Calloway, 1990; Clarke et al., 1991;
Cooper et al., 1992). It is currently being used in the UK
in the Medical Research Council Multi-Centre Study of
Cognitive Function and Ageing (MRC CFA Study) and
data will soon be available on over 3000 people aged
65 years and older from a nationally representative
sample, half of whom are being re-assessed annually
with CAMCOG. This study will provide norms on an uns-
elected elderly population as well as data on large
numbers of individuals with dementia.
To date, British norms are available only on a very elderly
cohort in Cambridge City aged over 75 years (Huppert
et al., 1995, 1996). Data from these studies are pre-
sented in Tables 2 and 3.
CAMCOG Profile
For clinical work, it is often useful to have a visual profile of
an individuals cognitive strengths and weaknesses. Jean
Hooper and Romola Bucks, two clinical psychologists
working with older adults in Gloucestershire, have devel-
oped the Cognitive Profile (Hooper & Bucks, 1993)based on CAMCOG subscales, which is scored manually.
A CAMCOG profile can also be obtained using com-
puter scoring and can be printed out from the CAMDEX-
R disk. We are currently developing a computerised
method for examining an individuals obtained versus
expected scores on the CAMCOG total and subscales,
based on his/her sociodemographic characteristics.
Health variables may also be included to examine the
extent to which an individuals cognitive impairment can
Table 2 Performance of an elderly population sample on CAMCOG subscales
Percent obtainingSubscale Maximum value Mean (SD) Median score maximum Range
Orientation 10 9.2 (1.0) 10 51 310Language 30 21.9 (2.6) 25 0 929Memory 27 20.7 (3.6) 21 0 426Attention 7 5.1 (1.9) 5 31 07Praxis 12 10.1 (2.0) 10 27 012Calculation 2 1.8 (0.4) 2 80 02Abstract thinking 8 5.2 (2.3) 5 20 08Perception 10* 7.8 (1.8) 8 16 110Total 106*
* For this community sample one item (recognising two people in the room) had to be omitted, reducing the number of itemsfrom 4 to 3, and the maximum score from 11 to 10. The total CAMCOG score was accordingly reduced from 107 to 106.Source: Huppert et al. (1995)
-
5/28/2018 CAMCOG.pdf
6/8
84 Detailed description
be explained by physical disorder or depression as
opposed to dementia (see Jorm, 1994).
Camcog Scores and Sociodemographic variables
CAMCOG scores, like scores on any cognitive test with
an adequate range, are markedly influenced by age, sex,
education and social class. This can be seen in Table 4.
For total CAMCOG score, all four variables exert a sig-
nificant effect even when the other three variables have
been controlled for. For CAMCOG subscales, the rela-
tionship is more complex, with age exerting a significant
effect on almost all subscales while the other variables
show selective effects. These findings make it clear that
sociodemographic variables must be taken into account
when judging whether an individual is impaired or not
impaired compared to the population average.
CAMCOG versus MMSE
CAMCOG examines a wider range of cognitive func-
tions than the MMSE and includes items graded in diffi-
culty. CAMCOG total score is more normally distributed
than MMSE scores (Fig. 1) and avoids ceiling effects.
Figure 2 shows that elderly people who obtain maximum
scores (29 or 30) on the MMSE are widely distributed in
terms of CAMCOG score.
Reliability
Total score on the CAMCOG was found to have excel-
lent internal reliability (Cochrans alpha 0.82, 0.89 in dif-
ferent samples) and testretest reliability (Pearson
correlation 0.86). The reliability of the individual sub-
Table 3 Mean scores of an elderly population sample on CAMCOG subscales
Age Group
7779 8084 8589 90+ All AgesCAMCOG Subscales (n=135) (n=191) (n=64) (n=28)
Orientation 9.5 9.3 8.8 8.9 9.2Language 25.4 25.2 23.5 23.8 24.9Memory 21.7 21.0 18.9 18.6 20.7Attention 5.5 5.1 4.7 4.5 5.1Praxis 10.5 10.3 9.3 8.8 10.1
Calculation 1.8 1.8 1.7 1.6 1.8Abstract thinking 5.6 5.2 4.4 4.6 5.1Perception 8.3 8.1 6.8 6.0 7.8
Source: Huppert et al., (1995)
Figure 1 (a) Distribution of CAMCOG scores(b) Distribution of MMSE scores
-
5/28/2018 CAMCOG.pdf
7/8
CAM CO G: Detailed description 85
scales, which corresponded to different cognitive abili-
ties, and which may sample qualitatively different
processes, was also acceptable. (Pearson test-retest
reliability 0.460.80). Reliability data are presented in
more detail in Huppert et al. (1996).
CAMCOG and Dementia
CAMCOG scores are very effective in differentiating
between demented and nondemented individuals.
Huppert et al. (1996) report that in an elderly population
sample the CAMCOG total score, as well as each
subscale score, differed significantly between non-
demented individuals and those with the diagnosis of
mild dementia or minimal dementia (Table 5). As well as
differentiating between groups, CAMCOG also differen-
tiates successfully between individuals. CAMCOG total
scores showed high levels of sensitivity and specificity in
differentiating between non-demented individuals and
those with a diagnosis of mild dementia. The cut-point
which produced the highest levels of both sensitivity and
specificity was 80/81, with values of 93% and 87%,
respectively (Table 6). CAMCOG score also predicts
dementia diagnosis. For each 1 point decrease in score,
there is a 20% increase in the probability of dementia
diagnosis.
These findings are described in more detail in Huppert et
al. (1996).
Figure 2 CAMCOG score for high MMSE scorers (29 or 30)
Table 4 Sociodemographic variables and CAMCOG performance
CAMCOG score
No. Female (%) Mean (SD) Median Range
SexMale 137 87.4 (9.5) 90 52102Female 281 67 83.7 (11.5) 86 31102
Age (years)7779 135 64 88.3 (9.1) 89 48102
8084 191 68 86.1 (9.8) 88 551028589 64 67 78.1 (13.3) 81 3110090+ 28 82 76.6 (10.7) 80 5189
Education* (age at leaving school)12/13 52 71 80.0 (12.8) 83 319814 242 64 84.3 (10.2) 86 4810215 52 73 88.0 (10.9) 90 5110216 44 66 87.5 (12.3) 92.5 5210017+ 26 88 90.4 (7.1) 91 67100
Social class*Professional/managerial 82 68 86.1 (10.9) 88 51102Skilled non-manual 74 73 88.2 (10.3) 90 48102Skilled manual 148 62 85.7 (10.1) 87.5 51100Semi-skilled/unskilled manual 103 69 81.4 (12.1) 85 31102
* It was not possible to establish education for 2 respondents, and social class for 1 respondent.Source: Huppert et al. (1995)
-
5/28/2018 CAMCOG.pdf
8/8
86 Detailed description
Table 5 Means (and SDs) on Cambridge Cognitive Examination (CAMCOG) and its Subscales as a
Function of Dementia Severity
Non-demented Minimal dementia Mild dementia
Subscale Mean (SD) Mean (SD) Mean (SD)
Orientation** 9.73 (0.57) 9.03 (0.96) 7.19 (1.83)
Language** 26.13 (2.27) 24.01 (2.20) 22.16 (3.75)Comprehension** 8.66 (0.63) 8.33 (0.82) 7.67 (1.34)Expression* 17.44 (2.00) 15.68 (1.83) 14.58 (2.83)
Memory** 22.18 (2.67) 18.41 (4.20) 14.74 (4.55)Remote Memory** 4.75 (1.21) 3.97 (1.44) 2.94 (1.47)Recent Memory** 3.82 (0.46) 3.37 (0.85) 2.23 (1.23)Learning** 13.56 (1.88) 11.09 (3.04) 9.30 (3.55)
Attention/Calculation* 6.91 (2.14) 5.16 (2.38) 4.32 (2.37)
Praxis** 1.57 (1.64) 9.40 (1.90) 8.10 (2.11)
Abstract Thinking** 5.78 (2.13) 4.64 (2.41) 2.58 (2.15)
Perception* 7.87 (1.80) 6.89 (1.88) 6.20 (1.53)
CAMCOG** 89.69 (8.49) 77.95 (9.72) 65.46 (1.69)
Note: Because of missing data, n = 291322 for non-demented, 6471 for minimal dementia and 4153 for mild dementia.
** All group means differ, P