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Vascular cognitive impairment and dementia

5th Edition
2015 UPDATE
June 2015

The Canadian Stroke Best Practice Recommendations for the Mood, Cognition and Fatigue following Stroke, 5th Edition (2015) is published in the International Journal of Stroke (IJS) and available freely online. To access the specific recommendations for Vascular cognitive impairment and dementia and all other sections of the Mood, Cognition and Fatigue module, please click on this URL which will take you to the recommendations online in the IJS: http://onlinelibrary.wiley.com/doi/10.1111/ijs.12557/full.

For the French version of these recommendations, open the appendix at this link : http://onlinelibrary.wiley.com/store/10.1111/ijs.12557/asset/supinfo/ijs12557-sup-0001-si.pdf?v=1&s=2416dbbaf6bc557a385758a55284840380cfe209

All other supporting information, including performance measures, implementation resources, evidence summaries and references, remain available through www.strokebestpractices.ca, and not through the IJS.  Please click on the appropriate sections on our website below for this additional content.

Rationale

Vascular cognitive impairment affects up to 60 percent of stroke survivors and is associated with poorer recovery and decreased function in activities of daily living and instrumental activities of daily living. Patients may require long-term, ongoing intervention and rehabilitation (Teasell et al, 2009; Madureira et al 2001). Cognitive abilities in the areas of executive function, attention and memory appear important in predicting functional status at discharge. In addition, cognitive impairment can be chronic and progressive after stroke; post-stroke dementia is estimated to occur in 26 percent of stroke patients by three months (95% CI 3% in age-matched controls) and adversely affects recovery. Cognitive impairment increases long-term dependence and is associated with increased mortality rates (61 percent versus 25 percent) (Black, 2007).

Cognitive impairment due to covert vascular pathology is also increasing. Covert strokes, visualized as lacunes or white matter hyperintensities on T2-weighted images, are common (23 percent of community elderly) and are associated with cognitive decline, dementia, and stroke. Evidence is emerging that demonstrates that for every clinically evident stroke, there may be up to ten covert strokes. Intracerebral small-vessel disease is a disorder that is on the rise with the aging of the population, leading to an increase in the need support services over the long term.

Emotional and related behavioural changes are known to occur following stroke, with specific behaviours linked to the affected hemisphere and stroke location.Disorders such as apathy, anxiety, labile laughing and crying, and other behaviours such as disinhibition, denial, indifference, overt sadness, and aggressiveness can occur in the early days following stroke. Some of these behaviours may be related to later development of depression; however, prospective studies of mood changes during and immediately after stroke are limited as yet.

In most population studies, vascular dementia is the second most common cause of dementia, after Alzheimer disease. The combination of Alzheimer disease and vascular disease results in the commonest substrate of dementia in the elderly. A single macroscopic hemispheric infarct is sufficient to cause dementia in people with intermediate Alzheimer pathology.

System Implications

  • Public education to increase awareness that cognitive changes may be considered as manifestations of vascular disease and stroke.
  • Public education to increase awareness of untreated or uncontrolled hypertension and other vascular risk factors and their relationship to cognitive changes and dementia.
  • Professional education to increase awareness among family physicians and primary care health professionals that patients with vascular risk factors, if not treated, will be at high risk for cognitive deficits.
  • Professional education across specialties (e.g., nephrology, ophthalmology, family medicine) to increase awareness that patients with small-vessel disease should be investigated for stroke risk factors and cognitive impairment.
  • Access to interprofessional teams with the expertise to appropriately manage patients with vascular cognitive impairment across the continuum of stroke care and in the community.
  • Mechanisms to ensure good communication and information flow between the range of specialists and programs beyond the core stroke care providers to meet the varied needs of individuals post stroke (e.g., mental health specialists, cognitive specialists, geriatric programs).
  • Continuing professional education to ensure proficiency in assessment administration, interpretation and management of patients demonstrating post stroke and vascular cognitive impairment or at risk of vascular cognitive impairment

Performance Measures

  1. Percentage of patients with stroke or stroke risk factors who undergo a brief cognitive screening at each transition point along the continuum of stroke care (i.e., acute inpatient care, inpatient rehabilitation, outpatient clinics and programs, home-based services, and stroke prevention clinics) and in the community following inpatient discharge and at any time when there is a suspected change in cognitive status. (Core indicator)
  2. Percentage of patients with stroke who are referred for more in-depth cognitive or neuropsychological assessment throughout the continuum of stroke care (for example, during inpatient care, inpatient rehabilitation, outpatient and ambulatory clinics or programs (stroke prevention clinics) and/or following inpatient discharge to the community.
  3. Percentage of change in cognition, e.g. Montreal Cognitive Assessment (MoCA) or other recommended measure scores at baseline and three months, six months and one year following initiation of therapy.
  4. Percentage improvement in control of high blood pressure and other vascular risk factors in patients with vascular cognitive impairment.
  5. Proportion of stroke patients diagnosed with VCI and according to cognitive domain at one month, 6 months and one year following stroke.

Measurement notes

  • Recommendations for VCI and corresponding performance measures apply across the continuum of stroke care and should be considered in acute inpatient care, inpatient rehabilitation, outpatient clinics, home-based services, and stroke prevention clinics and/or following inpatient discharge to the community.
  • When using these performance measures it is important to record when and in what context (continuum of care) the measurements were conducted. Data for measurement may be found through primary chart audit. Data quality will be dependent on the quality of documentation by healthcare professionals.
  • Performance Measure 3: Change will occur due to natural recovery in the absence of therapy, so for this measure to be meaningful this should be considered, and when possible conduct a comparison of change due to natural recovery versus change due to therapy.
  • This is a new area and will require a great deal of education for healthcare professionals especially in the area of documentation.

Implementation Resources and Knowledge Transfer Tools

Health Care Provider Information

Patient Information

Summary of the Evidence, Evidence Tables and References

Vascular Cognitive Impairment Evidence Tables and Reference List

It has been estimated that 5% of all people over the age of 65 years, in Canada, have evidence of vascular cognitive impairment (VCI). Vascular cognitive impairment refers to cognitive impairment due to all forms of cerebral vascular disease, including stroke, with severity that ranges from mild cognitive impairment to dementia (Gorelick et al., 2011, Rockwood et al. 2000). However, in individuals who have experienced stroke, reported VCI prevalence rates tend to be much greater, depending upon time post stroke, number of strokes and method of assessment, with values ranging from 61% in the acute phase (Hoffmann et al., 2001 to 21%-66% from 3 months to 14 years (e.g., Patel et al., 2003, Delgado et al, 2010, Douiri et al., 2013). While the risk for cognitive impairment is greater following stroke and, certainly, not all individuals with cognitive impairment have dementia, post-stroke cognitive impairment is associated with an increased risk for dementia.

Pendlebury and Rothwell (2009) conducted a systematic review and meta-analysis of 73 published studies examining prevalence and predictors of dementia in individuals with stroke. Overall, pooled prevalence of pre-stroke dementia was 14.4% in hospital-based cohorts (n=22) and 9.1% in community-based studies (n=8). Prevalence of post-stroke dementia ranged from 7.4% in population-based studies of individuals with first-ever stroke and no existing dementia to 41.3% in hospital-based studies of individuals with recurrent stroke (both with and without existing dementia). Rates of dementia were at least doubled following recurrent stroke when compared to first-ever stroke and were higher in hospital-based than in community-based studies. At 3- 6 months, post-stroke incidence of dementia was approximately 20%; this increased linearly at a rate of 3.0% in hospital-based studies of either first or recurrent stroke. Incidence rates were lower in population-based studies of first-ever stroke and when cases with recurrent stroke were excluded.

In the review by Pendlebury and Rothwell (2009), multivariate analyses were identified in 19 studies. From these 19 studies, the most commonly reported independent predictors of post-stroke dementia were older age, lower education level, previous stroke, diabetes, atrial fibrillation, pre-existing cognitive impairment and stroke severity. In summary, Pendlebury and Rothwell (2009) suggest that approximately 10% of patients have existing dementia at the time of stroke. An additional 10% develop new dementia shortly after a first-ever stroke while more than one-third of patients may experience dementia following a recurrent stroke. Recurrent stroke was identified as an important, and commonly cited, predictor of dementia. Gorelick (1997, 2004) reported on the risk factors for vascular dementia in 4 categories: demographic (older age, male sex, lower level of education), atherosclerotic (hypertension, smoking, myocardial infarction, diabetes, hyperlipidemia), genetic (cerebral autosomal dominant arteriopathy with subcortical infarct, leukoencephalopathy, apolipoprotein) and stroke-related (volume of cerebral tissue loss, evidence of bilateral cerebral infarction, strategic infarction, white matter disease).

Cognitive impairment following stroke has been associated with reduction in functional ability, and increased risk for depression (ebrsr.com). Individuals with cognitive impairments have greater functional impairment (Racic et al., 2011, Mok et al., 2004), increased dependency (Narasimhalu et al., 2011), show less clinical improvement (Cristea et al., 2006), and may require more therapy over longer periods of time (Zinn et al. 2004). In addition, the presence of executive dysfunction may have a negative impact on engagement in rehabilitation (Skidmore et al. 2010). A review by Leys et al. (2005) reported that higher rates of mortality have also been found among patients with post stroke dementia in both community-based and hospital-based studies. Overall, mortality rates are reported to be 2 to 6 times higher among individuals with post stroke dementia after adjusting for demographic factors, associated cardiac disease, stroke severity and stroke recurrence (Leys et al. 2005).

At present, there is no ‘gold standard’ for the diagnosis of vascular cognitive impairment. However, it has been recommended that given the anticipated presence of attention and executive dysfunction in cases of vascular cognitive impairment post stroke, any assessment used to detect the presence of VCI be appropriate to the assessment of these domains. As part of the development of the Canadian Stroke Network vascular cognitive impairment harmonization standards, Hachinski et al. (2006) outlined an assessment approach that provided recommended tests for a 5-min, 30-min or 60-minute testing protocol for the screening and assessment of VCI. The 5-minute and 30-minute testing protocols were intended for initial VCI screening (see Table 3 in Hachinski et al., 2006), while the 60 minute battery (Table 2) was provided to allow a breakdown of abilities by domain when needed for rehabilitation or other assessment purposes. Psychometric properties of the recommended tests are reviewed in Hachinski et al., 2006 and further information on screening tests used in stroke populations can be found in Table 2B of these guidelines. More research on the sensitivity and specificity of these protocols in screening for VCI is needed. Overall, the Montreal Cognitive Assessment (MoCA) test appears more sensitive to the presence of VCI compared to the Mini Mental State Examination (MMSE), particularly with mild deficits (e.g., Pendlebury et al., 2012, Godefroy et al., 2011, Toglia et al., 2011, Dong et al., 2010), although equivalence has been noted in other studies, notably with patients of moderate to severe strokes (Dong et al., 2012).   Inclusion of the Mini Mental Status Examination in the initial 5-minute Harmonization protocol was rejected, as it does not provide adequate assessment of executive function and is insensitive to mild memory impairment (Hachinski et al. 2006).

Cognitive rehabilitation interventions for VCI within the stroke population, focusing on common deficits of attention, memory or executive function are limited, but growing. In general, interventions may be considered to have one of two objectives: 1) to reinforce or re-establish previous behavioural skills or function (e.g., to remediate with computerized exercises ) or 2) to teach compensatory mechanisms (e.g., strategy training) that may be either internal or external to the individual (Cicerone 2000, 2005). Systematic reviews of cognitive rehabilitation interventions conducted by Cicerone et al. (2000, 2005) and updated in 2011, reported effect sizes for cognitive interventions in attention, visuospatial, language, memory and comprehensive training. Studies of attention or executive function, memory or comprehensive cognitive function were focused more often on individuals with TBI or other brain injury. Although generally positive results have been reported for studies examining the use of attention training, memory strategy training, use of mnemonic devices (e.g. personal pagers), and problem-solving training for study participants who have experienced brain injury (including stroke) evidence from randomized controlled trials specific to the stroke population was more limited (Cicerone et al, 2011; ebrsr.com). More recently, a systematic review by Cha & Kim, 2013 of the efficacy of computer-based cognitive rehabilitation revealed an overall effect size of 0.54 (medium effect), with no difference in acute or chronic stroke patients. Likewise, a recent Cochrane review (Loetscher & Lincoln, 2013) of attention rehabilitation (using various approaches) in stroke reported a significant treatment effect on specific, but not global, attention function, but with no evidence for impact on activities of daily living. In contrast, memory self-efficacy training was reported to improve subjective daily memory reports and quality of life in one RCT with 153 stroke patients in the chronic phase of stroke (Aben et al., 2013). Cicerone et al., 2011 also recommend use of external aids to improve function directly (e.g., alarms, pagers, notebooks) for severe memory impairment following stroke or TBI. In terms of executive dysfunction, while several small studies have reported benefits of meta-cognitive strategy training (Skidmore et al., 2014), goal management training (Levine et al., 2011) and problem solving skill training (Man et al., 2006) in stroke, recent reviews highlight the lack of strong evidence for these interventions at this time (Chung et al., 2013, Poulin et al, 2012).

Finally, physical exercise may also be beneficial for cognitive impairment post stroke as seen in a recent systematic review by Cumming et al., 2012. On the basis of 9 trials investigating the effect of exercise on cognition in stroke patients, they reported a significant, but small, pooled treatment effect (standardized mean difference = 0.2, 95%, CI 0.04 to 0.36, p=0.015).

Pharmacotherapy

Cholinergic agents have been used in the treatment of dementia of the Alzheimer’s type. Three such agents, donepezil, rivastigmine and galantamine, have also been investigated for use in the treatment of vascular dementia. Donepezil, a selective acetylcholinesterase inhibitor, has been the subject of 3 large randomized controlled trials (Black et al. 2003, Wilkinson et al. 2003, Roman et al. 2010). A meta-analysis of the first 2 trials demonstrated significant improvements in cognitive and global function, including improvements in the performance of activities of daily living associated with use of donepezil in the treatment of patients with mild to moderate vascular dementia (Passmore et al. 2005). The most recent trial also reported significant improvement in cognitive outcomes associated with treatment (Roman et al. 2010).

In randomized controlled trials, benefits on global function and functional status were not always congruent with benefits on cognition. A study of Vascular Dementia, which include pure and mixed cases showed beneficial effects in both cognition and function, but this was driven by the mixed Alzheimer and vascular cases. The pure Vascular Dementia subgroup showed only modest effects (Erkinjuntti, Lancet 2002, Craig Cochrane review, 2006). There was an attempt to replicate the study in pure Vascular Dementia, but only modest efficacy was shown for the cognitive measure and not for functional outcomes (Auchus, Neurology 2007).

Children and Vascular Cognitive Impairment

Cognitive outcomes for children with stroke must be considered differently. Covert VCI is not a common issue except in select disease states (moyamoya, sickle-cell, small vessel vasculitis). Most importantly, cognitive outcomes must be considered within the context of constantly evolving neurodevelopment. Thus, outcomes must use developmentally and age-appropriate outcome measures. Deficits in cognition and higher brain functions may not be evident until the relevant stage of development is reached, whereby young children “grow into” their deficits over time.[Westmacott et al. 2007a;Westmacott et al. 2009]

About 1 in 3 children with stroke have cognitive deficits at outcome, limiting academic, social, and independent functional success [Friefeld et al. 2004;Nass and Trauner 2004](Carr L 2011). Adverse cognitive outcomes from childhood cerebral sinus venous thrombosis (CSVT) [Wasay et al. 2008;deVeber et al. 2001;Moharir et al. 2010;Berfelo et al. 2010] and hemorrhagic stroke [Blom et al. 2003;Meyer-Heim and Boltshauser 2003] are also common. Overall cognitive function including intelligence, verbal ability, working memory, and processing speed are lower than average in children with stroke. (Westmacott, 2009), [Hetherington et al. 2005; McLinden et al. 2007] [Max 2004; Lansing et al. 2004].

Post-stroke psychiatric/behavioural disorders also appear to be common in childhood stroke (Max, 2002; Elbers 2013). Difficulties with social and behavioral development are also increased in children after stroke with secondary impact on parental mental health (De Schryver, 2002; Goodman, 2000). Limited studies suggest that social function is commonly impaired following stroke in childhood [Mosch et al. 2005]. Rates of potentially treatable Attention Deficit Hyperactivity Disorder (ADHD) are increased [Max et al. 2002;Max et al. 2003;Max et al. 2004], particularly with lesions involving the putamen [Teicher et al. 2000].

Contradicting the idea that the immature brain may be more plastic with a greater capacity for recovery, a younger age at stroke onset may be associated with worse cognitive and behavioural outcomes. (Westmacott, 2009; Everts, 2008)[Stiles 2000;Lansing, Max, Delis, Fox, Lancaster, Manes, and Schatz2004;Westmacott et al. 2007b]. There is also evidence for late emergence of cognitive deficits after perinatal stroke, with IQ measured in the preschool period higher than that measured later.(Westmacott, 2011) About one third of childhood stroke survivors require specialized education (Delsing, 2001). Regular, age-appropriate neuropsychological evaluations should be considered in all at-risk children to determine educational and support needs.