Screening for Stroke and Cognitive
Impairment
Chapter 3:
Cognitive Screening in Stroke
Screening
• By building screening for symptoms of VCI into regular
workflows or practice, health care providers are
participating in Taking Action to address cognition1.
• Clinicians must bear in mind that although screening can
provide highly useful information, it must not be confused
with formal evaluation.
• Rather, screening is for case finding to identify those who
warrant further cognitive evaluation.
Validation of Screening
in TIA/Stroke Outpatients
In a study by Pendlebury et al. (2012), the MoCA was
validated as a screen for cognitive impairment in stroke
prevention clinic patients in the UK returning >1 year after
TIA/stroke. A MoCA score of <25 (77% sensitivity, 83%
specificity) was found to be comparable to a MMSE<29
(77% sensitivity, 83% specificity)11.
Validation in Stroke Patients
The MoCA was also validated in the post stroke
population in France with higher sensitivity, but lower
specificity (MoCA<20; 94% sensitivity, 42%
specificity; MMSE<24; 66% sensitivity; 97%
specificity)8.
Who to Screen?
Canadian Best Practice Recommendation for Stroke Care 7.2.1:
http://www.strokebestpractices.ca/index.php/cognition-mood/vascular cognitive-impairment-anddementia/
• “All patients with vascular risk factors and those with
clinically evident stroke or transient ischemic attack should
be considered at increased risk for vascular cognitive
impairment (VCI), particularly in patients with cognitive,
perceptual or functional changes that are clinically evident
or reported during history taking.”1
Who to Screen?
Canadian Best Practice Recommendation for Stroke Care 7.2.1:
http://www.strokebestpractices.ca/index.php/cognition-mood/vascular cognitive-impairment-and-dementia/
Vascular risk factors include:
• Hypertension
• Diabetes
• Transient ischemic attack or clinical stroke,
• Atrial fibrillation
• Other cardiac disease, and/or
• Sleep apnea1.
In addition, all patients with:
• Neuroimaging findings of covert stroke or white matter disease
• Hypertension-associated damage to other target organs, should
also be considered for VCI screening1.
When to Screen
Canadian Best Practice Recommendation for Stroke Care 7.2.2:
http://www.strokebestpractices.ca/index.php/cognition-mood/vascular cognitive-impairment-and-dementia/
“All patients considered at high risk for cognitive impairment
should be assessed periodically throughout the stages of
care as indicated by the severity of clinical presentation,
history and/or imaging abnormalities to identify cognitive,
perceptual deficits, depression, delirium and/or changes in
function.”1
When to Screen
Canadian Best Practice Recommendation for Stroke Care 7.2.2:
http://www.strokebestpractices.ca/index.php/cognition-mood/vascular cognitive-impairment-and-dementia/
Cognitive Screening should occur through all stages and settings
following a stroke, including:
• “During presentation to emergency when cognitive, perceptual or
functional concerns are noted;
• During acute care stay, particularly if cognitive, perceptual or
functional concerns, or evidence of delirium is noted;
• Throughout rehabilitation within inpatient, outpatient, and homebased settings, according to client progress;
• Following hospital discharge from the emergency department or
inpatient setting to an outpatient or community-based healthcare
setting.”1
When to Screen
Canadian Best Practice Recommendation for Stroke Care 7.2.2:
http://www.strokebestpractices.ca/index.php/cognition-mood/vascular cognitive-impairment-and-dementia/
“While assessment at different stages of care is important for
guiding diagnosis and management, it is also important to be
aware of the potential impact of multiple assessments on
both the validity of the results as well as on the patient (e.g.,
test fatigue, practice effects).”1
Cognitive Screening Tools
Canadian Best Practice Recommendation for Stroke Care 7.2.1:
http://www.strokebestpractices.ca/index.php/cognition-mood/vascular cognitive-impairment-and-dementia/
“Screening for VCI should be conducted using a validated
screening tool, such as the Montreal Cognitive
Assessment”1 (MoCA) (www.mocatest.org)
A Summary of Select Screening Tools for Assessment of Vascular
Cognitive Impairment in Stroke Patients can be found at1:
http://www.strokebestpractices.ca/wp-content/uploads/2012/04/Table7.2B-EN.pdf
What is the MoCA?
•
The Montreal Cognitive Assessment, MoCA, was created in 1996 by
Dr. Ziad Nasreddine5.
•
It was validated in the setting of mild cognitive impairment, and has
subsequently been adopted in other clinical settings5.
•
The MoCA is a rapid screening instrument for mild cognitive
impairment5.
•
Poor sensitivity of the Mini-mental State Examination (MMSE) in
differentiating clients with mild cognitive impairment from elderly clients
led to the development of the MoCA. Therefore, it was meant to be used
in clients with a normal range score on MMSE6.
What is the MoCA?
www.mocatest.org:
• 30 point test;
• May be administered in approximately 10 minutes;
• The MoCA assesses several different cognitive domains:
•
•
•
•
•
•
•
•
Visuospatial / Executive
Naming
Memory
Attention
Language
Abstraction
Delayed Recall
Orientation5.
What is the MoCA?
• It can be used in a variety of settings and with culturally diverse
populations;
• The test is available in 36 languages and dialects;
http://www.mocatest.org/moca_news.asp
• Sensitive to detecting mild cognitive impairment;
• Applicable to the stroke population;
• Any health care professional with knowledge of the MoCA and how to
administer it, can use the MoCA;
• The test and administration instructions are readily available at
www.mocatest.org
• There is no cost5.
MMSE Background
• MMSE was developed to identify dementia, delirium and
cognitive changes over time6.
• A score of <26 is an indication of potential cognitive deficit6.
• It lacks sensitivity in detecting mild cognitive impairment and
early stages of dementia6.
• Additional limitations of the MMSE in the stroke population:
• Ineffective in differentiating between focal & diffuse lesions7.
• Performance is dependent on age, education factors,
ethnicity, and sociocultural background6.
• Insensitivity to right-sided lesions6.
MMSE vs. MoCA
•
2011 study by MacKenzie et al. examined 20 patients diagnosed with TIA
in a stroke prevention clinic7.
•
All were screened for cognitive impairment7.
•
MMSE was administered upon admission to the study and the MoCA was
administered 2 weeks later - scores were then compared7.
•
Findings demonstrated that patients were more likely to score as impaired
on the MoCA in comparison to the MMSE: 7
Comparison of MMSE and MoCA Scores
Instrument
Participants
scoring in
Normal Range
(> 26)
Mean
Score
Standard
Deviation
MMSE
90%
27.9
2.15
MoCA
45%
23.65
4.082
P=<0.05
MoCA vs MMSE
MoCA has been shown to be more sensitive screening tool than
MMSE in detecting the presence of cognitive impairment in the acute
stroke population8.
Possible Reasons for Increased Sensitivity:
• Memory testing involves more words, fewer learning trials and longer
delayed recall.
• More numerous and demanding tasks to assess for visuospatial
processing, executive functions, and language abilities.
• However, by adjusting the cut off scores it is sensitive to mild poststroke cognitive impairment (MMSE & MOCA are similar)8.