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Vascular Dementia

VARICOSE VEINS

See Vascular disease

VASCULAR DEMENTIA

Introduction

Vascular dementias (VaDs) are the second most common causes of dementia, but much still needs to be done to sort out some basic ideas about how to describe the area. In the first instance, vascular dementias (the plural is used because unlike, say, Alzheimers disease, there is clearly more than one type) are related to cerebrovascular disease. Cerebrovascular disease, however, is also related to Alzheimers disease (AD) so that vascular factors are cognitive impairment world-wide (Hachinski).

Historic and conceptual context

As early as 1896 arteriosclerotic dementia (referring to VaD) was separated from senile dementia (referring to AD). Nevertheless, until the 1960s and 1970s cerebral atherosclerosis by chronically impairing blood supply to the brain was thought to be the commonest cause of dementia, and AD was regarded as a rare cause affecting only younger patients. Tomlinson et al. (Tomlinson, Blessed, and Roth) rediscovered AD as the more frequent cause of dementia than that of arteriosclerotic dementia. In 1974 Hachinski and colleagues used the term multi-infarct dementia (MID) to describe the mechanism by which they considered VaD was produced (Hachinski, Lassen, and Marshall). As the pendulum swung in the direction of AD, vascular forms of dementia became relegated to a position of relative obscurity.

Until the 1990s, the concept of VaD has been dominated by MID, i.e., a dementia caused by small or large brain infarcts. VaD has come full circle to be understood as cognitive impairment caused by chronic ischemic with or without stroke.

Epidemiology

With the varying conceptions of vascular dementia, one understanding of epidemiology has been affected by variations in the definition of the disorders, the clinical criteria used, and the clinical methods applied.

Prevalence. VaD is the second most common single cause of dementia, accounting for 10 to 50 percent of the cases, depending on the geographic location, patient population and clinical methods used (Hebert, Brayne; Lobo et al.). The prevalence of VaD seems to be higher in China and Japan than in Europe and North America. In a recent European collaborative study using population-based studies of persons aged sixty-five years and older conducted in 1990s the age-standardized prevalence of dementia was 6.4 percent (all causes), 4.4 percent for AD and 1.6 percent for VaD (Lobo et al.). In this study 15.8 percent of the cases had VaD and 53.7 percent AD. As expected, a large variation in VaD prevalence was seen across studies. The prevalence ranged from 0.0 percent to 0.8 percent at age sixty-five to sixty-nine years, and from 2 percent to 8.3 percent at age ninety years and over in different studies. There was a difference in prevalence between men and women; under eighty-five years of age the prevalence of VaD was higher in men compared to women and thereafter the prevalence was higher in women.

Incidence. The incidence of VaD has varied between six to twelve cases per year in one thousand persons aged seventy years and older (Hebert and Brayne). The incidence of VaD increases with increasing age, without any substantial difference between men and women.

Prognosis. The mean duration of any VaD is around five years (Hebert and Brayne), and their survival is less than for the general population or AD. Post-stroke dementia is an independent predictor of mortality.

Post-stroke dementia

Recent studies from around the world have shown that CVD increases the risk of dementia. The risk is higher than those associated with any other known risk factor for dementia.

Etiology and pathophsyiology

VaD as a clinical syndrome relates to different vascular mechanisms and changes in the brain, and has different causes and clinical manifestations. As noted, VaD is not only the traditional dementia of multiple strokes (Erkinjuntti and Hachinski, 1993; Chui). The pathophsyiology of VaD incorporates interactions between vascular etiologies (CVD and vascular risk-factors), changes in the brain (in strokes, white matter lesions and atrophy), host factors (age, education) and cognition (see Figure 1).

Etiologies of VaD include both CVDs and risk factors (see Table 1). The main CVDs include large artery disease, cardiac embolic events, small vessel and hemodynamic mechanisms.

Risk factors for VaDs (see Table 1) include risk factors for CVD, stroke, white matter lesions, but, at the same time, also those of any cognitive decline and AD (Skoog).

Many changes in the brain are associated with VaD including several types of strokes, white matter lesions, and incomplete ischemic injury (occurring when brain cells are injured by chronic low blood flow to the brain.

Heterogeneity of vascular dementias

As reviewed, VaD is not a distinct disease, but a group of more or less heterogeneous syndromes. One way to clarify this heterogeneity is to study possible clinical subtypes. Subtypes of VaD included in current classifications are cortical VaD (or MID), the subcortical VaD (small vessel dementia) and hypoperfusion dementia. Further subtypes suggested include hemorrhagic dementia, hereditary vascular dementia, and combined or mixed dementia (AD with CVD).

Main subtypes of vascular dementia

Cortical VaD (MID) is seen in connection with large vessel disease, cardiac embolic events and also hypoperfusion (see Table 2). It shows predominantly cortical and cortico-subcortical arterial territorial and distal field (watershed) infarcts. Typical clinical features are changes in strength or sensation on one side of the body, with facial problems such as language impairment, comprehension, and abrupt onset of cognitive impairment.

Strategic infarct dementia. Focal, often small, ischemic lesions involving specific sites critical for higher cortical functions are usually classified separately from other types of VaD. A stroke in one specific area, known as angular gyrus can give a syndrome almost indistinguishable from Alzheimers disease, except that it has a sudden onset. Subcortical infarcts can also give rise to dementia. Depending on the strategic location in question, the time-course and clinical features vary greatly.

Subcortical VaD. This type of VaD incorporates two entities the lacunar state and Binswanger disease. It relates to small vessel disease and is characterized by lacunar infarcts, focal and diffuse ischemic white matter lesions, and incomplete ischemic injury.

Ischaemic lesions in substantial VaD affect not only the subcortical areas, but also their link to prefrontal cortex. Indeed, the so called subcortical syndrome is its primary clinical manifestation. This syndrome includes several factors, such as weakness without sensory changes, motor difficulties with speech and swallowing, a gait disorder, depression and emotional liability, and, especially, deficits in executive functioning. Patients with subcortical VaD often have multiple lacunes and extensive white matter lesions on neuroimaging often do not give a clinical history characteristic to stroke.

Mixed dementia

The so-called mixed dementia syndrome (which usually refers to the combination of Alzheimers disease and VaD) may have been underrepresented in our estimation of dementia subtypes. VaD and AD seem to be more closely linked than might be explained on the basis of coincidence. Several vascular risk factors related to VaD have been shown also to be risk factors of clinical AD. In addition, infarcts and WMLs relate to an earlier clinical manifestation of AD. Further VaD and AD also share common pathogenic mechanisms such as delayed neuronal death and apoptosis. Overlap of these two mechanisms relate especially to the late-onset AD.

Clinical recognition of patients with mixed dementia or AD with CVD can be a problem. These patients can give a clinical history and signs of CVD, in this respect being clinically closer to VaD. On the other hand, many patients with AD are only found to have ischemic features in the neurophosis. In search of the therapeutic approaches however, we may have to choose a new focus. Instead of being prisons of old diagnostic dichotomies (pure AD vs. pure VaD), we should change the focus on etiopathogenetic factors, measure both the vascular burden of the brain, as well as the Alzheimer burden of the brain, and their consequences.

Clinical features of subcortical and cortical VaD

The early cognitive syndrome of subcortical VaD is characterized by (1) dysexecutive syndrome including slowed information processing, (2) memory deficit (may be mild), and (3) behavioral and psychological symptoms. The dysexecutive syndrome in subcortical VaD includes impairment in goal formulation, initiation, planning, organising, sequencing, executing, setsifting and set-maintenance, as well as in abstracting. The memory deficit in subcortical VaD is often mild. Sometimes it is manifested by impaired recall but relatively intact recognition. In consequence, patients often benefit from cues. Mild disorders are also commonly seen in subcortical VaD as is incontinence.

Clinical neurological findings especially early in the course of subcortical VaD include mild upper motor neuron signs, gait disorder, imbalance and falls. Often, however, these focal neurological signs are subtle or even transient.

By contrast, patients with cortical VaD, more commonly exhibit the neurological signs classically associated with stroke.

Onset and course. In subcortical VaD, the onset is variable, whereas in cortical VaD, it is typically sudden, with a step-wise deterioration following.

Diagnostic criteria

Several sets of clinical criteria for VaD have been used. The two cardinal components of all clinical criteria for VaD are the definition of dementia, and the definition of a vascular cause.

Each of the sets of clinical criteria are consensus by symptom experts, compared with criteria based on experimental studies. Each is based on the MID model of VaD.

Differential diagnosis

The differential diagnosis of VaDs include a number of conditions (see Table 3), but chiefly AD.

In consequence, the focus in a clinical diagnosis of AD has been on early episodic memory impairment, followed by often cognitive features, with a progressive course, with progressive dependence in function. This picture is distinct from early classical VaD.

In its classical conceptual form, probable VaD is characterized by an abrupt onset, a fluctuating and stepwise course, signs of cerebrovascular disease and ischemic lesions on brain imaging. By contrast, AD is characterized by an insidious onset, progressive course, without clinical signs of CVD and without signs of CVD in brain imaging.

AD and CVD (Mixed dementia). The issue of mixed dementia is a challenge. Increasing evidence shows that different vascular factors are related to AD, and frequently CVD coexists with AD. This overlap is increasingly important in older populations. Clinical recognition of patients with mixed dementia or AD with CVD, however, is a problem. As detailed in the neuropathological series of Moroney et al., these patients have a clinical history and signs of CVD, being clinically closer to VaD. In fact, in this series, fluctuating course (OR 0.2) and history of strokes (OR 0.1) were the only items differentiating AD from the mixed cases.

Problematic clinical examples include stroke unmasking AD in patients with post-stroke dementia, insidious onset and/or slow progressive course in VaD patients, and cases where difficulty exists in assessing the role of less extensive WMLs or of distinct infarcts on neuroimaging. This clinical challenge may be solved when a sensitive and specific ante-mortal marker for AD is available, and the distinction between AD and VaD could be supported by more detailed knowledge on which site, type and extent of ischemic brain changes are critical for VaD and which extent and type of medial temporal lobe atrophy specifies AD.

Prevention and treatment of vascular dementia

Primary prevention aims to reduce the incidence of a disease by eliminating its causes or main risk factors. In VaD dementia the targets are CVD, including arterial hypertension, atrial fibrillation, myocardial infarction, coronary heart disease, diabetes, generalized atherosclerosis, lipid abnormalities and smoking. In addition, the use of estrogen, anti-inflammatory agents and antioxidants appear to reduce the risk of VaD.

Secondary prevention aims to prevent established disease from progressing. It emphasizes early detection and treatment. Treatment is aimed at treating the underlying cause, such as large artery disease (e.g., aspirin, dipyridamole, clopidragril, carotid endarterectomy), cardiac embolic events (e.g. anticoagulation, spirin), small-vessel disease (e.g. antiplatelet therapy as in large vessel disease), and hemodynamic mechanisms (e.g. control of hypotension and cardiac arrythmias).

How well all this works still is unclear. While a considerable degree of progress in our understanding of vascular dementia has been made, it is clear that much needs to be done before we will have effective treatment of this common and disabling problem.

Timo Erkinjuntti Kenneth Rockwood

BIBLIOGRAPHY

Chui, H. C. Rethinking Vascular Dementia: Moving from Myth to Mechanism. In The Dementias. Edited by J. H. Growdon and M. N. Rossor. Boston: Butterworth-Heinemann, 1998. Pages 377401.

Erkinjuntti, T., and Hachinski, V. C. Rethinking Vascular Dementia. Cerebrovascular Diseases 3 (1993): 323.

Erkinjuntti, T.; Bowler, J. V.; DeCarli, C.; et al. Imaging of Static Brain Lesions in Vascular Dementia: Implications for Clinical Trials. Alzheimers Dis Assoc Disord 13 (1999): S8190.

Erkinjuntti, T.; Ostbye, T.; Steenhuis, R.; and Hachinski, V. The Effect of Different Diagnostic Criteria on the Prevalence of Dementia. New England Journal of Medicine 337 (1997): 16671674.

Fratiglioni, L.; Launer, L. J.; Andersen, K.; et al. Incidence of Dementia and Major Subtypes in Europe: A Collaborative Study of Population-Based Cohorts. Neurology 54 (2000): S10S15.

Hachinski, V. Preventable Senility: A Call for Action Against the Vascular Dementias [see comments]. [Review]. Journal of the American Geriatrics Society 340 (1992): 645648.

Hachinski, V. C.; Lassen, N. A.; and Marshall, J. Multi-infarct Dementia. A Cause of Mental Deterioration in the Elderly. Journal of the American Geriatrics Society ii (1974): 207210.

Hebert, R., and Brayne, C. Epidemiology of Vascular Dementia. Neuroepidemiology 14 (1995): 240257.

Konno, S.; Meyer, J. S.; Terayama, Y.; Margishvili, G. M.; and Mortel, K. F. Classification, Diagnosis, and Treatment of Vascular Dementia. Drugs & Aging 11 (1997): 361373.

Lobo, A.; Launer, L. J.; Fratiglioni L.; et al. Prevalence of Dementia and Major Subtypes in Europe: A Collaborative Study of Population-Based Cohorts. Neurology 54 (2000): S4S9.

Moroney, J. T.; Bagiella, E.; and Desmond, D. W., et al. Meta-analysis of the Hachinski Ischemic Score in Pathologically Verified Dementias. Neurology 49 (1997): 10961105.

Rockwood, K.; Bowler, J.; Erkinjunti, T.; Hachinski, V.; and Wallin, A. Subtypes of Vascular Dementia. Alzheimer Dis Assoc Disord 13 (1999): S59S64.

Skoog, I. Status of Risk Factors for Vascular Dementia. [Review]. Neuroepidemiology 17 (1998): 29.

Tomlinson, B. E.; Blessed, G.; and Roth, M. Observations on the Brains of Demented Old People. Journal of the Neurological Sciences 11 (1970): 205242.

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Erkinjuntti, Timo; Rockwood, Kenneth. "Vascular Dementia." Encyclopedia of Aging. 2002. Encyclopedia.com. 31 May. 2016 <http://www.encyclopedia.com>.

Erkinjuntti, Timo; Rockwood, Kenneth. "Vascular Dementia." Encyclopedia of Aging. 2002. Encyclopedia.com. (May 31, 2016). http://www.encyclopedia.com/doc/1G2-3402200418.html

Erkinjuntti, Timo; Rockwood, Kenneth. "Vascular Dementia." Encyclopedia of Aging. 2002. Retrieved May 31, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3402200418.html

Vascular dementia

Vascular dementia

Definition

Dementia is a decline in a person's mental capacities and intellectual abilities that is great enough to affect the person's normal daily functioning. Vascular dementia is dementia that is caused by disease of the blood vessels of the brain (cerebrovascular disease).

Description

Vascular dementia is caused by cerebrovascular disease that occurs almost entirely in the elderly. People with vascular dementia generally experience a decline in thought processes (cognitive function) that follows specific steps. This decline is often punctuated by small strokesruptures of tiny blood vessels in the brain. People experiencing vascular dementia often have problems with memory, abstract thinking, object identification or recognition, speech creation, speech comprehension, and motor activities.

Causes and symptoms

The signs of dementia often begin with impaired memory function. Sometimes a person has difficulty learning new things or remembering new events, and sometimes the person has difficulty recalling events or things that he or she used to know. Other signs of dementia include impairment in other areas of thought processing. Sometimes a person with vascular dementia may have difficulty producing coherent speech, or may have other language impairments, such as problems understanding spoken or written language. The signs of vascular dementia are similar to those of Alzheimer's disease (AD).

Difficulty with motor activities is a problem for some people with vascular dementia. Things that require hand-eye coordination, such as tying shoes or undoing buttons, are examples of motor activities that may be impaired. People with vascular dementia may also have difficulty recognizing familiar objects, or may be unable to name them. Problems organizing things, putting events in sequence, or problems performing other types of abstract thinking may be present.

Some people with vascular dementia exhibit neurological signs that indicate the presence of cerebrovascular disease. They may have weakness of the arms or legs, abnormal reflexes, or abnormalities in the way they walk. Some people also exhibit behavioral disturbances related to the dementia. A person can be violent or aggressive towards othersoften his or her caretaker. The person may act impulsively and irritably, and sometimes scream.

Vascular dementia is thought to be caused by small strokes that interfere with blood flow to the brain. Usually, vascular dementia is caused by many small strokes over time, rather than one large stroke . Sometimes this is referred to as multi-infarct dementia (MID). If the vascular dementia is caused by one large stroke, or develops in less than three months, then it is called "acute onset vascular dementia." Acute onset vascular dementia is rare.

Demographics

In most countries, vascular dementia is a much less common form of dementia than AD. This is true in North America and Europe, but is not so in Japan, where it is more common than AD. Overall, vascular dementia is the second most common form of dementia, after AD. About 1020% of patients who experience dementia have the vascular form of the disorder. The difference in prevalence in different countries may result from different lifestyle factors rooted in the culture.

Vascular dementia is more common in men than in women, which may be because men are more likely than women to suffer from strokes. Vascular dementia becomes increasingly prevalent as people grow older. The number of people affected by vascular dementia rises dramatically during and after the sixth decade. Vascular dementia usually occurs at a younger age than AD.

Diagnosis

The first step in the diagnosis of vascular dementia is to verify that dementia is present. The DSM indicates that impairments to memory must be present for a diagnosis of vascular dementia. Memory problems can include difficulties in learning and retaining new information, problems remembering past events, or things that were learned before dementia took root.

In addition to memory impairment, the DSM also specifies that one or more other impairments must be present. These impairments can include language problems that encompass not being able to form speech and/or not being able to understand language, either spoken or written. The patient may have problems performing activities that require hand-eye coordination such as tying shoes, even though motor function is normal. Another possible impairment is a problem recognizing or identifying objects, although the person is able to use his or her sense organs fully. Also, problems doing tasks such as organizing things, planning events, putting things into sequence, or problems thinking abstractly may exist.

If the patient has memory problems and one or more other impairments, For a diagnosis of vascular dementia to be made, these impairments must cause problems for the patient's functioning in important parts of his or her daily life. Also, the patient must be significantly less able to function than during a previous time. In addition, the problems cannot occur during the course of an event that is categorized as a delirium . There must be evidence that the problem is a result of cerebrovascular disease.

If the dementia occurs without any other significant signs or symptoms, then it is classified as uncomplicated. There are three other possible classifications as given by the DSM. These are based on the predominant feature of the dementia. They are: vascular dementia with delirium, vascular dementia with delusions , and vascular dementia with depressed mood. If there are significant behavioral disturbances occurring as a result of the dementia, then that is specified.

Vascular dementia and AD are similar in many ways, and can be confused. The most significant difference between the two is that vascular dementia can be diagnosed using physiological evidence of cerebrovascular disease. Also, AD generally occurs first as a slow loss of memory function, and then as a gradual decline into eventual dementia. Vascular dementia, however, generally occurs suddenly. The patient often declines in a stepwise fashion, with each step occurring after a stroke.

Treatments

The treatments for vascular dementia focus on attempts to slow or halt the progression of the disorder and alleviate some of the symptoms. The disorder cannot be cured or reversed. The most common way to treat vascular dementia is to try to prevent further strokes. Treatments include diet and drug treatment for hypertension (high blood pressure), aspirin therapy, smoking cessation, avoidance of heavy alcohol use, and stress reduction. Some drugs that are used to treat mild AD are being studied for their effectiveness in treating vascular dementia.

Prognosis

Vascular dementia is a disorder that cannot be reversed. The progression of the disorder can, however, be slowed. Using drugs, along with lifestyle changes to prevent more strokes from occurring, can be effective at slowing the progression of vascular dementia.

Prevention

Vascular dementia is generally associated with a series of strokes causing increasing mental impairment. Measures generally recommended by physicians may prevent strokes and may be effective in helping to prevent vascular dementia. These measures include such things as quitting smoking, decreasing cholesterol levels, treating hypertension by reducing sodium (salt) intake, decreasing alcohol consumption, quitting smoking, and other lifestyle changes. One study illustrated that consuming a small amount of red wine regularly reduces the risk of all forms of dementia.

See also Alzheimer's disease

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th ed., text revised. Washington DC: American Psychiatric Association, 2000.

Sadock, Benjamin J. and Virginia A. Sadock, eds. Comprehensive Textbook of Psychiatry. 7th ed. Vol. 2. Philadelphia: Lippincott Williams and Wilkins, 2000.

PERIODICALS

Anonymous. "New Alzheimer's Drug is First Therapy to Show Efficacy in Vascular Dementia." Formulary 36 no. 8 (August 2001): 596.

Buchalter, Eric N., Melinda S. Lantz. "Treatment of Impulsivity and Aggression in a Patient with Vascular Dementia." Geriatrics 56 no. 2 (February 2001): 53.

Gross, Joel S., Joshua R. Shua-Haim. "Multi-infaract Dementia: a Common Form of Dementia Associated with Cerebrovascular Disease." Geriatrics 52 no. 5 (May 1997): 95.

Jagust, William. "Untangling Vascular Dementia." The Lancet 358, no. 9299 (December 22 2001): 2097.

Larson, Eric B. "Illness Causing Dementia in the Very Elderly." The New England Journal of Medicine 328, no. 3 (January 21 1993): 203-2055.

ORGANIZATIONS

National Institute on Aging. Building 31, Room 5C27 31 Center Drive, MSC 2292 Bethesda, MD 20892. Telephone: (301) 496-1752. Web site: <www.nia.nih.gov>.

Tish Davidson, A.M.

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Davidson, Tish. "Vascular dementia." Gale Encyclopedia of Mental Disorders. 2003. Encyclopedia.com. 31 May. 2016 <http://www.encyclopedia.com>.

Davidson, Tish. "Vascular dementia." Gale Encyclopedia of Mental Disorders. 2003. Encyclopedia.com. (May 31, 2016). http://www.encyclopedia.com/doc/1G2-3405700403.html

Davidson, Tish. "Vascular dementia." Gale Encyclopedia of Mental Disorders. 2003. Retrieved May 31, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3405700403.html

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