Alzheimer's Quick Test cognitive screening criteria for West African speakers of Krio

Abstract

To obtain normative data for Alzheimer's Quick Test (AQT) measures of perceptual and cognitive speed from West African speakers of Krio.
Normal adults, who were functionally independent, from Sierra Leone (n = 164) aged 25-79 years.
Perceptual and cognitive speed were measured with AQT single- and dual-dimension colour-number (C-N) and colour-animal (C-A) naming tasks. Tests were administered individually in the participants' communities.
Men and women performed similarly (P>0.05), whereas literate speakers used significantly less time than preliterate peers (P<0.01). Correlations between age and colour naming were low (P<0.01) and speed decreased by <0.1 s per year. Dual-dimension naming remained stable across ages. Correlations with years of education were low for dual-dimension naming (P<0.01) and speed increased approximately 0.4 s per added year. Correlations between age and education and AQT naming were non-significant for literate participants. Criterion time cut-offs (seconds) for screening were developed for preliterate and literate speakers of Krio for typical (<+1 SD), slower-than-typical (between +1 and +2 SD) and atypical (>+2 SD) performance.
AQT C-N and C-A naming are time efficient (3-5 min each), objective and reliable and can be administered in Krio to West African adults in Africa, Europe or North America to screen for cognitive impairments and facilitate referral for medical workup.

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Alzheimer’s Quick Test cognitive screening
criteria for West African speakers of Krio
NIELS PETER NIELSEN
1
, ELISABETH H. WIIG
2
1
Department of Psychiatry, Hvidovre Hospital, Vesterbrogade 31, Copenhagen, Denmark
2
Knowledge Research Institute, Inc., 7101 Lake Powell Drive, Arlington, TX 776016-3517, USA
Address correspondence to: Elisabeth H. Wiig. Tel: (+817) 572 6254. Fax: (+817) 478 1048. Email: ehwiig@krii.com
Abstract
Objectives: to obtain normative data for Alzheimer’s Quick Test (AQT) measures of perceptual and cognitive speed from
West African speakers of Krio.
Subjects: normal adults, who were functionally independent, from Sierra Leone (n = 164) aged 25–79 years.
Methods: perceptual and cognitive speed were measured with AQT single- and dual-dimension colour–number (C–N) and
colour–animal (C–A) naming tasks. Tests were administered individually in the participants’ communities.
Results: men and women performed similarly (P>0.05), whereas literate speakers used significantly less time than preliterate
peers (P<0.01). Correlations between age and colour naming were low (P<0.01) and speed decreased by <0.1 s per year.
Dual-dimension naming remained stable across ages. Correlations with years of education were low for dual-dimension naming
(P<0.01) and speed increased ∼0.4 s per added year. Correlations between age and education and AQT naming were non-sig-
nificant for literate participants. Criterion time cut-offs (seconds) for screening were developed for preliterate and literate
speakers of Krio for typical (<+1 SD), slower-than-typical (between +1 and +2 SD) and atypical (>+2 SD) performance.
Conclusion: AQT C–N and C–A naming are time efficient (3–5 min each), objective and reliable and can be administered in
Krio to West African adults in Africa, Europe or North America to screen for cognitive impairments and facilitate referral
for medical workup.
Keywords: cognitive processing speed, attention/executive, set shifting, screening criteria, elderly
Introduction
With rapid global growth in elderly populations, it is import-
ant to find behavioural measures to differentiate normal
ageing from cognitive impairments caused by disease proc-
esses. This is challenging, as normal performance varies
because of hereditary, developmental, educational or envi-
ronmental factors [1, 2]. There is limited information about
normal cognitive ageing [3–7] and none for African adults.
This is in spite of the estimates that the African population
over the age of 65 years would grow from 17.7 to 37.9 mil-
lion from 1997 to 2025 [8]. This study provides measures of
normal cognitive ageing in West African Krio speakers,
obtained with simple, objective and reliable processing-
speed tests with broad cultural/linguistic application [9].
Tests of content are typically used to screen for cogni-
tive impairment and decline associated with neurological
conditions. However, they introduce cultural, linguistic
and/or educational biases, when used outside Western cul-
tures for which they were developed. The common meas-
ure, Mini-Mental State Examination (MMSE) [10, 11],
shows limitations in differentiating normal function from
Alzheimer’s disease (AD) [12, 13]. Thus, MMSE showed spe-
cificity of 100% and sensitivity of 84%, whereas Alzheimer’s
Quick Test (AQT) colour–form (C–F) naming [9] showed
specificity of 97% and sensitivity of 97%. Educated West-
erners readily perform the MMSE tasks, but abilities
required for subtraction, reading and writing might not be
developed in societies where literacy is not generally estab-
lished. It is, therefore, of importance for the developing
societies to identify cognitive-screening measures that are
quick, reliable, objective and cross-culturally applicable, and
can be administered with minimal training. These consider-
ations prompted the collection of normative data for AQT
colour–number (C–N) and colour–animal (C–A) naming [9]
from functionally intact West African speakers of Krio.
AQT assesses processing speed (i.e. time to complete a
controlled-input task) with rapid naming. Processing-speed
tests are sensitive to small changes in time, and older adults
typically use longer time than younger adults [14–16]. Simi-
larly, AQT dual-dimension (C–N and C–A) naming shows
significant, but small, time increases with age for American
adults below the age of 60 years (1 s per decade) and slightly
larger increases after age 60 (1 s per seven years) [5]. Nam-
ing times are not affected by gender [9, 17].
The AQT naming tasks are criterion-referenced for nor-
mal adults in the US, Sweden and Greece, and cut-offs
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N. P. Nielsen and E. H. Wiig
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(seconds) for typical, slower-than-typical and atypical nam-
ing speeds are reported [9, 17, 18]. Test–retest reliability is
high, and effects of age on naming are similar for American
and Swedish speakers [9, 17]. Speakers of Greek require a
higher cut-off point (100 s) for atypical C–F naming than
American and Swedish speakers (∼+30 s) [18].
Sustained naming causes redistribution of cerebral blood
flow. During AQT C–F naming, normal adults show
increased blood flow to temporal–parietal brain regions
bilaterally and suppressed flow to frontal regions compared
with the rest [9, 17, 19, 20]. C–F naming shows high sensi-
tivity (93.1–98.7%) and specificity (96.6–99.9%) and differ-
entiates Swedish and Greek adults with mild-to-moderate
AD from cognitively normal peers [17, 18], and in differen-
tiating AD from dementia with Lewy bodies [21]. AQT
dual-dimension naming assesses attention/executive func-
tions mediated by temporal–parietal activation [22––24].
This study was descriptive and objectives were prag-
matic. They were as follows: (i) to obtain normative data for
AQT C–N and C–A naming from West African speakers of
Krio, (ii) to compare naming times and effects of ageing for
Krio and American speakers and (iii) to develop culturally/
linguistically appropriate criterion cut-offs (seconds) for
typical, slower-than-typical and atypical performance.
Methods
Participants
There were 59 women and 105 men (mean age 44.6 years, SD
9.5). All gave informed consent in accordance with the Decla-
ration of Helsinki. A well-being questionnaire about patterns
of eating, sleeping, working and mood and absence of fever,
neurological disorders, diabetes and HIV screened partici-
pants. Adults with neurological disorders or HIV, or who did
not meet the criteria for well-being, were excluded. Partici-
pants were recruited from the members of the Lutheran com-
munity, and each was paid $5.00 by the authors. All were
natives of Sierra Leone, equally distributed between urban
(Freetown) and rural areas. Participants completed between 2
and 17 years of education (M 10 years, SD 4 years). A total of
45 participants had recurring malaria and 119 were malaria
free. Participants included housewives, day workers, traders
and professionals, who led functionally independent lives in
which they shopped, held jobs and performed societal
responsibilities. Owing to their roles in the society, all were
presumed to function within the normal cognitive range and
to be free of cognitive impairments or dementia that would
interfere with their work or societal functions.
Materials and administration
A trained examiner, native of Sierra Leone, administered the
tests individually in Krio, the lingua franca for trading and
social interactions, which blends English, French and Por-
tuguese. Participants completed testing in one session in
their community settings, and short trials established ade-
quacy of naming test stimuli.
AQT C–N and C–A each consists of three tests. Test 1
requires naming of 40 squares (e.g. black, blue, red or
yellow) and Test 2 naming either 40 numbers (e.g. 2, 4, 5 and
7) or animals (e.g. bird, cat, fish, rat, snake and spider) ren-
dered in black. Tests 1 and 2 measure perceptual speed (i.e.
perception + response time). Test 3 requires naming of 40 C–
N (e.g. red circle and blue square) or C–A (e.g. yellow fish and
black spider) combinations and measures cognitive speed (i.e.
perceptual speed + cognitive overhead). Test–retest reliability
(r) is high for C–N (0.91) and C–A naming (0.96).
Naming times for each test were measured digitally,
beginning at voice onset, and recorded in seconds and in
fractions of seconds. Data from 144 American speakers
with a mean age of 39.6 years (SD 15.9) were used for com-
parison. One-way ANOVA indicated no significant differ-
ences in age between Krio and American speakers (F =
3.20; P>0.05).
Statistical analyses
Naming times (seconds) were used in the analyses for the
total group (n = 164), men (n = 105) and women (n = 59),
preliterate (n = 41) and literate (n = 123) speakers and
speakers with (n = 45) and without (n = 119) malaria. The
analyses (SPSS Version 11.0.2 for Macintosh) produced
descriptive statistics, one-way and univariate ANOVA com-
parisons, correlations (r) and linear regression coefficients
(b). Measures of variability (SD) and cumulative frequencies
were used to establish criterion cut-off times (seconds).
Results
Background variables
AQT naming times (seconds) for Krio speakers are summa-
rised in Table 1. Single-dimension naming times are about
one-third shorter than the dual-dimension times. Means for
men and women did not differ significantly for colour,
number, animal or C–A naming (F = 0.96–2.37; P>0.05).
C–N naming was significantly faster among women than
men (F = 6.55; P<0.01).
Mean time differences between (i) preliterate (n = 41)
and literate adults (n = 123) and (ii) adults with (n = 45) and
without malaria (n = 119) were tested. One-way ANOVA
with literacy as a factor (i.e. education above age 15/Grade
8) [25] indicates significantly shorter C–N (M = 55.30, SD
20.37) and C–A (M = 76.14, SD 23.52) times for literate
than for preliterate speakers (M = 73.10, SD 17.67; 82.98,
SD 14.36) (F = 8.19 and 12.01; P<0.01). Naming times by
literate Krio (n = 123) and American speakers (n = 144) were
compared. Means (seconds) for Americans were as follows:
colour—20.91 (SD 3.31), number—14.26 (SD 2.72), C–
N—41.04 (SD 6.75), animal—25.74 (SD 3.75) and C–A—
48.29 (SD 7.18). All differences were significant (P<0.01)
(F = 43.09, 21.65, 11.08, 44.30 and 36.85). Univariate
ANOVA with age and years of education as independent
variables tested interaction effects. For C–N, age was not
significant (F = 1.32), whereas education (F = 2.24;
P<0.05) and the age–education interaction were significant
(F = 0.81; P>0.05). For C–A, the effects for age (F = 1.52),
education (F = 1.23) and interaction (F = 1.11) were all
non-significant (P>0.05).
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AQT cognitive screening criteria
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Mean differences between speakers with (n = 45) and
without (n = 119) malaria were significant (P<0.05) for col-
our, C–N and C–A naming (F = 5.66, 20.63 and 9.50).
Adults with malaria completed 12.0 (SD 2.5) and adults
without malaria completed 9.8 (SD 3.7) years of education,
which is a significant difference (F = 11.67; P<0.01).
Age and education effects
In the total group (n = 164), correlations (r) between age
and colour and animal naming were significant (−0.23
and −0.17; P<0.05), whereas correlations with number,
C–N and C–A were not (−0.09, −0.15 and −0.03; P>0.05).
Significant relationships between age and naming times
were analysed using linear regression (Table 2). Coeffi-
cients for age effects for colour and animal naming indi-
cated increases (slowing of speed) of 0.05 and 0.08 s per
year. Age accounted for 5% of the variance in colour and
3% in animal naming time.
Correlations (r) were significant between education and
colour, C–N and C–A naming (−0.19, −0.38 and −0.28;
P<0.05), whereas correlations with number and animal nam-
ing were not (−0.03 and −0.13; P>0.05). Linear regression
(Table 2) indicated decreases in time (increased speed) of 0.14
s for colour, 0.43 s for C–N and 0.46 s for C–A naming per
added year of education. The relationships were described by
the following equations: C–N = 82.96 + (−2.25) (education)
and C–A = 94.97 + (−1.67) (education). Education
accounted for 3% of the variance in colour, 14% in C–N and
8% in C–A naming time. In the previous research, education
after the age of 15 years (Grade 8) did not affect AQT dual-
dimension naming times [1, 19]. Therefore, correlations (r)
were calculated between years of education and C–N and C–
A naming for literate Krio speakers (n =123). There was no
significant correlation for C–N (r = −0.14; P>0.05), but there
was for C–A naming (r = −0.29; P<0.01).
Criterion cut-offs
Normative ranges for typical, slower-than-typical and atypi-
cal naming times for literate (n = 123) and preliterate (n =
41) Krio speakers were developed by previously employed
methods [9, 17] (Table 3). Times (seconds) shorter than +1
SD above the mean indicated typical, longer than +2 SD
above the mean indicated atypical (potentially pathological)
and between +1 and +2 SD indicated slower-than-typical
performance. Cut-off times were adjusted to lend parsi-
mony and ease of reference for screening.
Cut-off criteria for literate Krio speakers were compared
with criteria for literate American and Swedish speakers for
C–N (typical <50 s; slower 51–59 s; atypical >60 s) and C–
A naming (typical <60 s; slower 61–69 s; atypical <70 s) [9,
17]. This indicated a difference in cut-off criteria of 25–30 s
for C–N and 40–50 s for C–A naming.
Discussion
Normative naming times were obtained from Krio speakers
for AQT C–N and C–A naming, and criterion cut-offs were
developed for potential cognitive screening. C–F naming,
explored in clinical research [9, 13, 17–20], was not adminis-
tered because of rare use of names for geometric forms in West
African daily life. The study assumed a macro-perspective
Table 1. AQT means and standard deviations for the total group of West African speakers of Krio and subgroups based on
gender, literacy and malaria
*One-way ANOVA F values for the comparison significant at P<0.01. Statistical differences between subgroups and F values are reported in the results section.
....................................................................................................................................
.
Measure [Mean (SD)]
Groups Colour Number Colour–number Animal Colour–animal
.................................................................................................................................................................................
T
otal (n = 164) 30.73 (6.09) 19.48 (5.72) 59.39 (21.06) 37.60 (9.20) 77.80 (21.72)
Men (n = 105) 30.99 (5.75) 19.06 (5.81) 62.56* (21.29) 38.25 (9.80) 79.22 (20.73)
W
omen (n = 59) 29.98 (7.10) 20.24 (5.54) 54.00* (19.84) 36.12 (7.62) 74.51 (23.62)
Preliterate (n = 41) 30.71 (5.83) 17.59 (3.57) 73.10* (17.67) 39.83 (10.65) 82.98* (14.36)
Literate (n = 123) 30.49 (6.50) 20.05 (6.18) 55.30* (20.37) 37.07 (8.74) 76.14* (23.52)
Malaria (n = 45) 28.76 (7.28) 19.38 (6.71) 48.04* (12.84) 36.18 (8.18) 69.27* (26.63)
Free from malaria (n = 119) 31.32 (5.69) 19.50 (5.32) 63.87* (21.96) 38.12 (9.51) 80.74* (18.89)
Table 2. Linear relationships between age and years of education and AQT naming times (seconds) for Krio speakers (n = 164)
V
ariable Naming time Constant B
0
Coefficient B
1
P r r-squared
.................................................................................................................................................................................
A
ge Color 23.97 0.15 <0.01 0.23 0.05
Animal 45.10 −0.17 <0.05 0.17 0.03
Education Color 34.28 −0.34 <0.05 0.19 0.03
Colour–number 82.96 −2.25 <0.01 0.38 0.15
Colour–animal 94.97 −1.67 <0.01 0.28 0.08
Table 3. Criterion cut-off times for typical, slower-than-
typical and atypical performance for preliterate and literate
adult speakers of Krio
Group AQT test Typical Slower-than-typical Atypical
.....................................................................................
Preliterate Colour–number <90 s 91–109 s >110 s
Colour–animal <110 s 111–129 s >130 s
Literate Colour–number <75 s 76–94 s >95 s
Colour–animal <100 s 101–124 s >125 s
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N. P. Nielsen and E. H. Wiig
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where dual-dimension naming times were considered sympto-
matic of broader attention/executive functions (e.g. attention,
working memory and set shifting) [20, 22–24].
Women named the C–N stimuli on average 10 s faster
than men, a counterintuitive finding, as men tend to be the
traders. More importantly, men and women used similar
times for dual-dimension naming, concurring with the find-
ings for American and Swedish speakers [1, 5, 17]. Age did
not significantly affect dual-dimension naming either.
Education (literacy) influenced C–N, but not C–A nam-
ing speed. This seems appropriate, as colour naming and
number naming are part of the curriculum in West African
schools, and longer exposure should result in greater cogni-
tive speed. Interactions between age and education were not
significant for dual-dimension naming. As a group, Krio
speakers were significantly slower at naming both single-
and dual-dimension stimuli than American speakers [5].
Even literate Krio speakers used considerably longer time
than literate Americans to name stimulus combinations.
Age and education
Associations between age and naming times were low and
only reached significance for perceptual speed measures.
Age accounted for less variance in colour naming for Krio
(5%) than for American speakers (8%) [5]. Associations
between years of education and dual-dimension naming
were low, but significant, and speed increased by about 2 s
for each added year of education. Education accounted for
relatively large proportions of the variance in C–N and C–A
naming (15 and 8%, respectively).
The association between education and naming time was
evident in adults with and without malaria. Adults with
malaria, and more advanced education, used on average 10 s
less for C–N and 20 s less for C–A naming than malaria-free
adults. This supports that achievement of literacy results in
greater cognitive flexibility. In the literate group, there was
no significant association between education and C–N nam-
ing. This concurs with the findings that education past
established literacy has little effect on dual-dimension nam-
ing among American and Swedish adults [9, 17].
Implications for screening
Criterion cut-offs for AQT naming are identical for Ameri-
can and Swedish speakers [9, 17, 18, 20]. Because Krio
shares features of English in content and structure, similari-
ties in naming times would be expected. However, criterion
cut-offs for the lower limits of atypical performance for
Krio speakers are more than 30 s longer than cut-offs for
American speakers [9]. The difference may reflect cultural
traditions for rate of speech in West Africa or other uncon-
trolled factors.
Speed, ease of administration and equity of access are
desirable screening-test qualities in societies with limited
education. The advantages of using C–N over C–A naming
with West African Krio speakers were therefore considered
based on variability, biases and expressed preferences. C–N
and C–A naming showed similar variability, but the majority
preferred C–N to C–A naming. Although C–N or C–A
naming may be used alone for screening, best clinical
practice suggests administering both the tasks (5–7 min total)
until clinical utility data become available. We also suggest
repeating administration of dual-dimension tests with atypi-
cal naming times (>+2 SD) for consistency and validation.
Results suggest that AQT C–N and C–A can be used for
first-line screening of Krio speakers in West Africa, Europe
or North America to identify adults, who may require fur-
ther evaluation for cognitive impairment and/or dementia.
The tests are not intended for diagnostic purposes, because
they are sensitive to cognitive impairments resulting from a
range of neurological and psychiatric disorders. If naming
time consistently falls in the atypical range, referral for med-
ical workup is recommended. If naming time falls within the
slower-than-typical range, periodic screening is recom-
mended to identify if significant reductions in cognitive
speed (+15 s or more), which may be indicative of a pro-
gressive disorder, have occurred.
Current health priorities in West Africa concern individ-
uals who are HIV positive. Growth in the elderly popula-
tion will, however, demand attention to detecting cognitive
impairments, resulting from dementia or other causes.
While prescription medications for AD are unavailable to
most West Africans, the cultures have long histories of
treating illness, including memory loss, with herbal constitu-
ents and compounds, justifying early identification.
Key points
• Normative data for AQT C–N and C–A naming were
collected from 164 functionally intact speakers of Krio in
Sierra Leone.
• Naming speed was significantly faster for literate than for
preliterate speakers.
• Age had no significant effect on dual-dimension naming
times.
• Years of education affected dual-dimension naming
times in the total group, but not in the group of literate
speakers.
• Criterion cut-offs were developed separately for screen-
ing literate and preliterate West African speakers of Krio.
Conflicts of interest
None.
Acknowledgements
We express our gratitude to the Evangelical Lutheran
Church of Sierra Leone, its staff and members. We are espe-
cially indebted to Bishop Tom Barnett for supporting the
study and to the Reverend Marie Barnett for collecting the
data. This research received no third party funding.
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