Quick Start: Vascular Cognitive Impairment and Vascular Dementia
Definition
Vascular cognitive impairment is the overarching term used when cognitive dysfunction is due to cerebrovascular disease (i.e., strokes).
Vascular dementia (VaD) occurs when cerebrovascular disease causes cognitive dysfunction that significantly impairs daily functioning.
Vascular mild cognitive impairment (VaMCI) occurs when cerebrovascular disease causes cognitive dysfunction that does not significantly impair daily functioning.
The exact cerebrovascular disease that can cause cognitive and functional impairment may be varied, and can include:
Small vessel ischemic disease
Multiple cortical strokes
Strategic infarcts
Cerebral amyloid angiopathy.
Prevalence
Approximately 5% to 10% of patients with dementia have a pure vascular dementia, that is, dementia entirely due to cerebrovascular disease.
Another 10% to 15% of patients with dementia suffer from a mixed dementia of cerebrovascular disease plus a neurodegenerative disease.
Almost all patients with cognitive impairment due to a neurodegenerative disease have some cerebrovascular disease that makes at least a small contribution to their cognitive difficulties.
Genetic risk
The genetic risk is related to the varied underlying cerebrovascular pathology.
One disorder, CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy), is due to mutation of the Notch3 gene at the chromosome locus 19p13.
Cognitive symptoms
Neuropsychological testing typically shows impairment in multiple domains, including attention, frontal/executive function, and speed of processing. Memory impairments are typically secondary to attention and frontal/executive dysfunction.
Diagnostic criteria
Mild vascular cognitive impairment (VaMCI): Impairment in at least one cognitive domain and mild to no impairment in instrumental activities of daily living (IADLs)/activities of daily living (ADLs), respectively (independent of the motor/sensory sequelae of the vascular event).
Major vascular cognitive impairment (VaD): Clinically significant deficits of sufficient severity in at least one cognitive domain (deficits may be present in multiple domains) and moderate to severe disruption to IADLs/ADLs (independent of the motor/sensory sequelae of the vascular event).
Magnetic resonance imaging (MRI) is the gold standard for a diagnosis of vascular cognitive impairment. If only computed tomography (CT) is available, the diagnostic certainty is lowered to “probable.” If neither MRI nor CT are available, the diagnostic certainty is lowered to “possible.”
Full diagnostic criteria are available from the Vascular Impairment of Cognition Classification Consensus Study (VICCCS) (see Box 7.1 ) and the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) (see Box 7.2 ).
Box 7.1
Vascular Impairment of Cognition Classification Consensus Study Diagnosis Guidelines
Modified from Skrobot, O. A., Black, S. E., Chen, C., et al. (2018). Progress toward standardized diagnosis of vascular cognitive impairment: Guidelines from the Vascular Impairment of Cognition Classification Consensus Study. Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, 14 (3), 280–292.
Definitions and Diagnosis of Vascular Cognitive Impairment (VCI)
Clinical evaluation and neuropsychological protocols should include assessment of executive function, attention, and memory, as well as language and visuospatial function. a
a National Institute of Neurological Disorders–Canadian Stroke Network guidelines are recommended.
Mild VCI (vascular mild cognitive impairment; VaMCI): Impairment in at least one cognitive domain and mild to no impairment in instrumental activities of daily living (IADLs)/activities of daily living (ADLs), respectively (independent of the motor/sensory sequelae of the vascular event).
Major VCI (vascular dementia; VaD): Clinically significant deficits of sufficient severity in at least one cognitive domain (deficits may be present in multiple domains) and moderate to severe disruption to instrumental activities of daily living (IADLs)/activities of daily living (ADLs) (independent of the motor/sensory sequelae of the vascular event).
Patients given a diagnosis of major VCI (VaD) are subcategorized according to the underlying vascular pathology as appropriate. A clear temporal relationship (within 6 months) between a vascular event and onset of cognitive deficits is only required for a diagnosis of poststroke dementia (PSD).
Subtypes of Major VCI (VaD)
Poststroke dementia (PSD): A patient described as having poststroke dementia may or may not have presented evidence of mild cognitive impairment before stroke. The patient will exhibit immediate and/or delayed cognitive decline that begins within 6 months after a stroke and that does not reverse. Poststroke dementia can result from several different vascular causes and changes in the brain. It encompasses dementia that develops within 6 months of stroke in patients with multiple cortical-subcortical infarcts and strategic infarcts; patients with subcortical ischemic vascular dementia; and those with various forms of neurodegenerative pathology, including Alzheimer’s disease. The temporal relationship between the cognitive decline and the stroke differentiates poststroke dementia from other forms of major VCI (VaD).
Mixed dementias: A standalone umbrella subgroup termed “mixed dementias” includes phenotypes representing each combination between vascular and neurodegenerative disease, that is, VCI-Alzheimer’s disease, VCI–dementia with Lewy bodies, and so forth. It is recommended that a patient is referred to as having “VCI-Alzheimer’s disease,” for example, according to the clinically probable phenotypes, rather than the less-specific “mixed dementia.” Where discrimination is possible, the order of terms should reflect the probable relative contribution of the underlying pathology, that is, Alzheimer’s disease-VCI or VCI-Alzheimer’s disease.
Subcortical ischemic vascular dementia: Small vessel disease is the main vascular cause of subcortical ischemic vascular dementia. Lacunar infarcts and ischemic white matter lesions are the main type of brain lesions, which are located predominantly subcortically. This diagnosis incorporates the overlapping clinical entities of Binswanger’s disease and the lacunar state.
Multi-infarct dementia: Multi-infarct dementia is used to indicate the presence of multiple large cortical infarcts and their likely contribution to the dementia.
“Probable” and “Possible”—Terms for the Availability of Evidence
Magnetic resonance imaging is a “gold-standard” requirement for a clinical diagnosis of VCI . a
Probable mild VCI (VaMCI) or probable major VCI (VaD) is the appropriate diagnostic category if computed tomography imaging is the only means of imaging available. a
Possible mild VCI (VaMCI) or possible major VCI (VaD) would be appropriate diagnoses if neither MRI nor computed tomography imaging were available.
In diagnosis of VCI when full clinical assessment of the cognitive impairment due to the clinical event is impaired by aphasia, patients with documented evidence of normal cognitive function (e.g., annual cognitive evaluations) before the clinical event that caused aphasia could be classified as having probable mild VCI (VaMCI) or major VCI (VaD) if imaging is available, and the assessment of activities of daily living should be made where possible. If imaging is not available, the classification should be possible mild VCI (VaMCI) or major VCI (VaD).
Those at Risk of VCI
It is recommended that greater consideration for diagnosis be given to people who are at risk of VCI if they present with at least 6 months of sustained impairment (even if very mild), rather than transient impairment, as identified through caregiver reporting and clinical observation. All other potential causes of sustained impairment (e.g., depression or vitamin D deficiency) should have been excluded.
Exclusions From Diagnosis
Drug/alcohol abuse/dependence within the last 3 months of first recognition of impairment or delirium.
Box 7.2
Diagnostic and Statistical Manual of Mental Disorders, 5th Edition Criteria for Major or Mild Vascular Neurocognitive Disorder
From American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (DSM-5) (5th ed.). Arlington, VA: American Psychiatric Publishing, Inc.
A.
The criteria are met for major or mild neurocognitive disorder.
B.
The clinical features are consistent with a vascular etiology, as suggested by either of the following:
1.
Onset of the cognitive deficits is temporally related to one or more cerebrovascular events.
2.
Evidence for decline is prominent in complex attention (including processing speed) and frontal-executive function.
C.
There is evidence of the presence of cerebrovascular disease from history, physical examination, and/or neuroimaging considered sufficient to account for the neurocognitive deficits.
D.
The symptoms are not better explained by brain disease or systemic disorder.
Probable vascular neurocognitive disorder is diagnosed if one of the following is present; otherwise possible vascular neurocognitive disorder should be diagnosed:
1.
Clinical criteria are supported by neuroimaging evidence of significant parenchymal injury due to cerebrovascular disease (neuroimaging-supported).
2.
The neurocognitive syndrome is temporally related to one or more documented cerebrovascular events.
3.
Both clinical and genetic (e.g., cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) evidence of cerebrovascular disease is present.
Possible vascular neurocognitive disorder is diagnosed if the clinical criteria are met but neuroimaging is not available and the temporal relationship of the neurocognitive syndrome with one or more cerebrovascular events is not established.
Behavioral symptoms
Depression is often present.
Treatment
There are no U.S. Food and Drug Administration (FDA)-approved medications to treat vascular cognitive impairment. However, clinical trials have found both cholinesterase inhibitors and memantine to be helpful. For memory problems we recommend a trial of cholinesterase inhibitors, and for apathy we recommend a trial of memantine.
Dextromethorphan/quinidine (Nuedexta) can be used for pseudobulbar affect.
Aerobic exercise and Mediterranean-style diets may be beneficial.
The underlying cause of the cerebrovascular disease must also be evaluated and treated.
Top differential diagnoses
Mixed dementia (vascular cognitive impairment plus another neurodegenerative disease such as Alzheimer’s disease or Lewy body disease), Alzheimer’s disease, depression.
A 74-year-old man presented to the clinic with a 6-year history of cognitive and functional decline. His family reported that his problems began with “small TIAs.” When we asked them what they meant, they explained that he appeared to be suffering from transient ischemic attacks, such that in a single day he might show a sudden decline in his speech, handwriting, and gait, which would subsequently improve, although not back to his baseline. Despite earning a degree in engineering, he had difficulty at that time with simple calculations, such as calculating the tip in a restaurant. He also had difficulty remembering a short list of items, and finding his way around a familiar street. His family also reported that he would often cry or laugh either inappropriately or with the least provocation.
His medical history included diabetes mellitus type 2 and hypertension. His review of systems was notable for frequent urinary and occasional fecal incontinence. His neurological examination was notable for brisk reflexes throughout. He had bilateral Babinski responses. On the Montreal Cognitive Assessment (MoCA) he scored 23 out of a possible 30, missing points on the alternating number-letter connect-the-dots, clock hands, serial 7s, and delayed recall (although with category cues and multiple choice he recalled the items he missed on delayed recall).
Prevalence, Prognosis, and Definition
Vascular cognitive impairment (VCI) is now the preferred, overarching term for cognitive impairment due to cerebrovascular disease (i.e., strokes) ( Fig. 7.1 ). When cerebrovascular disease causes cognitive dysfunction but not severe enough to lead to functional impairment, the terms mild vascular cognitive impairment (mild VCI) and vascular mild cognitive impairment (VaMCI) are used. When cerebrovascular disease causes cognitive dysfunction severe enough to cause impairment of instrumental or basic activities of daily living (see Box 2.2 ), the terms major vascular cognitive impairment (major VCI) and vascular dementia (VaD) are used ( Table 7.1 ).
Table 7.1
Comparison Between Vascular Dementia, Vascular Mild Cognitive Impairment, Alzheimer’s Disease Dementia, and Mild Cognitive Impairment due to Alzheimer’s Disease
Vascular Dementia
Vascular Mild Cognitive Impairment
Alzheimer’s Disease Dementia
Mild Cognitive Impairment due to Alzheimer’s Disease
Cognitive complaints by patient or family
Present
Present
Present
Present
Cognitive deficits
Present
Present, very mild
Present
Present, very mild
Functional impairment
Present
Absent
Present
Absent
Dementia
Present
Absent
Present
Absent
Likely underlying pathology
Cerebrovascular disease
Cerebrovascular disease
Alzheimer’s disease
Alzheimer’s disease
Deterioration over time
May occur, but may also remain stable
May occur, but may also remain stable
Always occurs
Occurs if diagnosis correct
U.S. Food and Drug Administration–approved treatment
None
None
Cholinesterase inhibitors, memantine
None
Recommended treatment
Cholinesterase inhibitors
Cholinesterase inhibitors
Cholinesterase inhibitors
Cholinesterase inhibitors
Memantine if apathy
Memantine if apathy
Memantine if apathy
Selective serotonin reuptake inhibitor (SSRI) if depression or anxiety
SSRI if depression or anxiety
SSRI if depression or anxiety
SSRI if depression or anxiety
The prevalence of vascular dementia and vascular mild cognitive impairment depends on how they are defined. If vascular dementia is defined such that patients with Alzheimer’s disease and other neurodegenerative diseases are excluded, then vascular dementia is a relatively small cause of memory loss and dementia, of the order of 5% to 10% of all dementias, depending upon the particular population (closer to 10% in U.S. veterans, for example). We would describe such patients as having a “pure vascular dementia.” Like most older adults, the majority of patients with Alzheimer’s disease and other degenerative diseases (such as dementia with Lewy bodies) have some cerebrovascular disease, usually in the form of small vessel ischemic disease. If these patients were also included in the definition of vascular dementia, then the majority of patients with dementia would have vascular dementia or vascular mild cognitive impairment—along with another type of dementia ( ). It is the unusual patient who has a single pathology; most patients have at least two pathologies contributing to their cognitive impairment and many have three or more ( ). One study found that vascular disease pathology contributed approximately 25% to late-life dementia due to clinical Alzheimer’s disease ( ).
We typically classify the cognitively impaired patient with cerebrovascular disease in one of the following ways. If the patient shows no signs of any other etiology of his or her cognitive impairment we would describe him or her as having a “pure vascular dementia” (or “pure vascular mild cognitive impairment,” if not demented). If the patient has a neurodegenerative disease (such as Alzheimer’s) and they have the average amount of cerebrovascular disease that a nondemented, noncognitively impaired older adult has, we would describe them as simply having that neurodegenerative disease (such as Alzheimer’s). If the patient has a neurodegenerative disease (such as Alzheimer’s) and they have a greater than average amount of cerebrovascular disease—such that it is highly likely that the cerebrovascular disease is making a significant contribution to the patient’s dementia—then we would describe them as having a “mixed dementia,” and would then further specify, for example, “a mixed dementia of Alzheimer’s disease plus vascular dementia” or “a mixed dementia of vascular dementia plus Alzheimer’s disease,” depending upon which was more prominent ( Fig. 7.2 ), consistent with the current diagnostic criteria ( ) ( Box 7.1 ). Patients classified in this way with a mixed dementia of cerebrovascular disease plus a neurodegenerative disease probably make up 10% to 15% of all dementias.
Criteria
There are many published criteria for vascular dementia. Two that we find helpful are those from the Vascular Impairment of Cognition Classification Consensus Study (VICCCS; ) and the DSM-5; they can be found below in Boxes 7.1 and 7.2 . (See Box 3.1, Box 3.3 for DSM-5 criteria for major and mild neurocognitive disorder.) Both criteria include that:
the cognitive disorder can be major or mild
history, exam, and/or neuroimaging evidence of cerebrovascular events is required
cognitive deficits in attention, processing speed, and frontal-executive function are common
a temporal relationship between cognitive deficits and cerebrovascular events is supportive.
Risk Factors, Pathology, and Pathophysiology
The major risk factors for vascular dementia and vascular mild cognitive impairment are, of course, the risk factors for cerebrovascular disease in general, with the major ones being hypertension, heart disease, smoking, and diabetes. See Box 7.3 for additional common risk factors.
Box 7.3
Risk Factors for Vascular Dementia and Vascular Mild Cognitive Impairment
Cardiovascular
Clinical strokes or transient ischemic attacks
Hypertension
Atrial fibrillation
Coronary artery disease
Atherosclerosis
Metabolic
Diabetes
Increased cholesterol
Habits
Smoking
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