The CANS-MCI presents the following progression of tasks to the subjects:
- Presents progressively more difficult General Reaction Time tasks that prepare the subject for the first test.
- Presents 4 pictures of objects with one word, & the user is instructed to touch the picture that goes with the word.
- User consecutively learns 5 sets of names of 4 pictures by touching pictures that fit into categories and then being told the name of the pictured object in that category.
- User is tested after each set of 4 pictures and the set is re-learned if mistakes were made.
- 20 3-button displays, each with an object name learned and 2 incorrect names from other categories are presented, with category-guided recall and re-acquisition of missed items.
- Presents 8 designs paired with letters in non-alphabetical order, & a set of 8 letters in alphabetical order.
- 1 of the designs appears in the middle of the screen, & the user is instructed to touch the letter paired with it.
- Complexity of attention-switching required is increased by within & between-test interference.
- Changes are made to the designs halfway through this test to present several types of interference.
- 10 clock blank faces are presented.
- A digital time is presented, & the user is instructed to first touch the hour hand position on the blank click face, then the minute hand position.
- User quickly touches buttons matching names of colors presented.
- User is then instructed to touch buttons matching the ink color, not the word name, of the words “Red”, “Blue” or “Green”, presented one at a time in either red, blue, or green ink.
- Pictures in multiple categories are presented, each with 4, 2-letter word beginnings, 1 naming the picture.
- One additional recognition test trial, with guided recall for missed items.
Table 2. Test Re-Test Reliability
|Test||Time 1 Mean (SD)||Time 2 Mean (SD)||Coefficient Alpha|
|General Reaction Time||0.77 (.21)||0.73 (.17)||.702|
|Design Matching (accuracy)||38.05 (11.41)||41.37 (8.94)||.765|
|Clock Test (accuracy)||30.65 (9.45)||32.86 (8.89)||.792|
|Stroop Discordant Item (reaction
|1.69 (.48)||1.61 (.52)||.794|
|Guided Recognition (accuracy)|
|Immediate||17.73 (2.01)||18.13 (1.86)||.681|
|Delayed||17.58 (2.27)||17.83 (2.25)||.607|
|Immediate & Delayed (combined)||35.23 (4.21)||35.95 (3.87)||.760|
|Guidance Efficacy||0.86 (.15)||0.90 (.14)||.385|
|Picture Naming (accuracy)||31.59 (4.81)||32.00 (4.91)||.788|
|Picture Naming (reaction time)||6.18 (2.13)||5.90 (2.26)||.854|
|Word/Picture Matching (reaction
|2.06 (.56)||1.93 (.49)||.833|
Table 3: Correlations of Standardized Tests with CANS-MCI Tests
|Conceptual Domain (CANS-MCI)||CANS-MCI Test||Standardized Test||Correlation Coefficient||P-value|
|Attention||General Reaction Time||Digit Symbol||-.585||<.001|
|Visuospatial ability||Design Matching (accuracy)||Digit Symbol||.537||<.001|
|Spatial relations||Clock (accuracy)||Digit Symbol||.469||<.001|
|Mental control||Stroop Discordant Item (latency)||Digit Symbol||-.565||<.001|
|Memory acquisition||Guided Recognition-Immediate||Mattis Memory
|Guidance Efficacy||Mattis Memory
|Memory retention||Guided Recognition-Delayed||Mattis Memory
|Composite memory score||Guided Recognition-Immediate & Delayed||Mattis Memory
|Picture naming||Picture Naming (accuracy)||Mattis Initiation||.584||<.001|
|Picture Naming (latency)||Mattis Initiation||.616||<.001|
|Other fluency tests||Word/Picture Matching (latency)||Mattis Initiation
Table 4: Diagnostic Validation using Delayed Memory Criterion
|Variable||WMS-II ≤ 10% Mean (SD)||WMS-II > 10% Mean (SD)||P-value|
|Age||80 (8.4)||76 (8.4)||.01|
|Years of formal education||13 (3.1)||15 (2.7)||.02|
|General Reaction Time||.91 (.28)||.73 (.17)||.000|
|Design Matching (accuracy)||29 (13.0)||40 (10.1)||.000|
|Clock (accuracy)||24 (8.8)||32 (8.9)||.000|
|Stroop Discordant Item (latency)||1.94 (.51)||1.64 (.45)||.000|
|Guided Recognition (accuracy)|
|Immediate||15 (2.7)||18 (1.4)||.000|
|Delayed||15 (3.2)||18 (1.8)||.000|
|Immediate & Delayed (combined)||30 (6.4)||36 (2.8)||.000|
|Picture Naming (accuracy)||27 (5.1)||32 (4.3)||.000|
|Picture Naming (latency)||8.4 (3.1)||5.8 (1.6)||.000|
|Word/Picture Matching (latency)||2.57 (.69)||1.95 (.46)||.000|
Table 5. Exploratory Factor Analysis (N=132)
|CANS-MCI Tests||Language/Spatial Fluency||Executive Function/Mental Control||Episodic Memory|
|General Reaction Time||-.294||-.741||.046|
|Stroop Discordant Item (reaction time)||-.169||-.791||-.126|
|Free Recognition-Immediate (accuracy)||.562||.119||.660|
|Free Recognition- Delayed (accuracy)||.682||-.120||.492|
|Picture Naming (accuracy)||.780||.308||.184|
|Picture Naming (reaction time)||-.825||-.242||-.231|
|Word/Picture Matching (reaction time)||-.543||-.568||-.167|
|WAIS Digit Symbol||.377||.635||.301|
Reliability: Internal consistency: Alpha coefficient reliabilities; Test-retest: Pearson correlations.
Validity: Concurrent: Pearson correlations with the scores on previously validated measures to provide a standard against which the component tests could be assessed.
Diagnostic: T-tests used to analyze differences between subjects in the lowest 10th percentile of cognitive functioning & those in the highest 90th percentile based on WMS-R LMS II scores.
Factor Analysis: Exploratory principal components factor analysis with Varimax rotation & Kaiser normalization.
Confirmatory factor analysis: presented at the American Association of Geriatric Psychiatry Convention, March, 2003.
Internal Consistency: Only 2 tests, Guided Recognition-Delayed (accuracy) & Guided Recognition-Guidance Efficacy, did not meet the predetermined standard for internal consistency (alpha >= .70) Other alpha coefficients ranged from .76-.97 (Table 1).
1 Month Test-Retest Reliability: Correlations over a 1-month period ranged from .607-.854 (Table 2). All but 3 had scores over .70. Separately, the Guided Recognition Immediate & Delayed accuracy tests had alphas below .70. When the immediate & delayed recall tests were combined to form a more global memory measure, the alpha was an acceptable .76. Guidance Efficacy had a very low test-retest alpha. Because Guidance Efficacy scored below the cut-off criteria in both inter-item & test-retest reliabilities, it was not included in further analyses.
Concurrent Validity: The correlations between the CANS-MCI & the previously standardized measures were moderate but all highly significant. Correlation coefficients ranged from .440 to .636 (p<.001) (Table 3).
Diagnostic Validation: Groups of impaired & intact memory subjects were established to assess the degree to which the CANS-MCI was able to detect impairments in cognitive abilities that are diagnostic of MCI or AD. Significant differences were observed between the memory intact group & the memory-impaired group on all CANS-MCI subtests (p<.001) (Table 4).
Factor Analysis: Results suggest a 3-factor solution that explained 63% of the total variance. The factors were Recognition Retrieval/Language, Executive Functions & Episodic Memory Acquisition (Table 5).
Reliability: The CANS-MCI demonstrates a high degree of internal consistency & test-retest reliability. These measures of test stability are comparable to those of the standardized comparison tests. Thus, the CANS-MCI can be reliably used at one or multiple testing sessions. Slight improvements in the mean scores are evident on all tests over the one-month period, probably
due to the reduction of anticipatory anxiety & establishment of positive relationships with the participants.
Validity: Cross validation of the CANS-MCI with the WMS-R LMSI & II, WAIS Digit Symbol & Mattis subscales demonstrates that the CANS-MCI subtests produce meaningful score differentiation of the memory impaired & non-memory impaired elderly. This is confirmed by an analysis based upon a WMS-R LMS II diagnostic criterion.
Factors: The factor analysis indicated that CANS-MCI items loaded onto 3 main factors: Recognition Retrieval/Language, Executive Functions, & Episodic Memory Acquisition. Design Matching & Word/Picture Matching loaded heaviest on Executive Functions but also heavily on Recognition Retrieval/Language, reflecting the overlap of cognitive domains when recognition ability is measured with psychomotor speed tests. Immediate & Delayed Recognition loaded most heavily on the Episodic Memory Acquisition factor but also loaded heavily on the Recognition Retrieval/Language factor.
As effective treatments for AD emerge, it will become important to identify people in primary care office visits who have the earliest signs of the cognitive impairments most likely to become AD. The CANS-MCI tests are reliable & differentiate memory impaired from normal elderly, as determined by the WMS-R LMS II. The CANS-MCI is an easily self-administered, valuable primary care screening tool for MCI to determine whether more intensive testing for cognitive impairment and possible dementia is warranted.
Screen, Inc. Seattle WA, USA
Department of Veterans Affairs, Seattle, WA, USA
Weschler Memory Scale-Revised Logical Memory Components I & II (WMS-R LMS I & II); Mattis Dementia Rating Subscales (Mattis)-Attention, Conceptualization, Inititation, Memory; Weschler Adult Intelligence Scale, Digit Symbol Component (WAIS)