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Dementia (meaning "deprived of mind") is a serious cognitive disorder. It may be static, the result of a unique global brain injury or progressive, resulting in long-term decline in cognitive function due to damage or disease in the body beyond what might be expected from normal aging. Although dementia is far more common in the geriatric population, it may occur in any stage of adulthood. This age cutoff is defining, as similar sets of symptoms due to organic brain syndrome or dysfunction, are given different names in populations younger than adult. Up to the end of the nineteenth century, dementia was a much broader clinical concept.

Dementia is a non-specific illness syndrome (set of signs and symptoms) in which affected areas of cognition may be memory, attention, language, and problem solving. It is normally required to be present for at least 6 months to be diagnosed; cognitive dysfunction that has been seen only over shorter times, in particular less than weeks, must be termed delirium. In all types of general cognitive dysfunction, higher mental functions are affected first in the process. Especially in the later stages of the condition, affected persons may be disoriented in time (not knowing what day of the week, day of the month, or even what year it is), in place (not knowing where they are), and in person (not knowing who they are or others around them). Dementia, though often treatable to some degree, is usually due to causes that are progressive and incurable.

Symptoms of dementia can be classified as either reversible or irreversible, depending upon the etiology of the disease. Less than 10 percent of cases of dementia are due to causes that may presently be reversed with treatment. Causes include many different specific disease processes, in the same way that symptoms of organ dysfunction such as shortness of breath, jaundice, or pain are attributable to many etiologies. Without careful assessment of history, the short-term syndrome of delirium (often lasting days to weeks) can easily be confused with dementia, because they have all symptoms in common, save duration, and the fact that delirium is often associated with over-activity of the sympathetic nervous system. Some mental illnesses, including depression and psychosis, may also produce symptoms that must be differentiated from both delirium and dementia.Chronic use of substances such as alcohol as well as chronic sleep deprivation can also predispose the patient to cognitive changes suggestive of dementia.

Signs and symptoms

Comorbidities

Dementia is not merely a problem of memory. Additional mental and behavioral problems often affect people who have dementia, and may influence quality of life, caregivers, and the need for institutionalization.

Depression affects 20-30% of people who have dementia, and about 20% have anxiety. Psychosis (often delusions of persecution) and agitation/aggression also often accompany dementia. Each of these needs to be assessed and treated independent of the underlying dementia.

Risk to self and others

The Canadian Medical Association Journal has reported that driving with dementia could lead to severe injury or even death to self and others. Doctors should advise appropriate testing on when to quit driving.

In the United Statesmarker, Florida's Baker Act allows law enforcement and the judiciary to force mental evaluation for those suspected of suffering from dementia or other mental incapacities.

In the United Kingdommarker, as with all mental disorders, where a sufferer could potentially be a danger to themselves or others, they can be detained under the Mental Health Act 1983 for the purposes of assessment, care and treatment. This is a last resort, and usually avoided if the patient has family or friends who can ensure care.

The United Kingdommarker DVLA (Driving & Vehicle Licensing Agency) states that Dementia sufferers who specifically suffer with poor short term memory, disorientation, lack of insight or judgement are almost certainly not fit to drive - and in these instances, the DVLA must be informed so said license can be revoked. They do however acknowledge low-severity cases and early sufferers, and those drivers may be permitted to drive pending medical report.

Diagnosis

Proper differential diagnosis between the types of dementia (cortical and subcortical - see below) will require, at the least, referral to a specialist, e.g., a geriatric internist, geriatric psychiatrist, neurologist, neuropsychologist or geropsychologist. However, there exist some brief tests (5–15 minutes) that have reasonable reliability and can be used in the office or other setting to screen cognitive status for deficits that are considered pathological. Examples of such tests include the abbreviated mental test score (AMTS), the mini mental state examination (MMSE), Modified Mini-Mental State Examination (3MS), the Cognitive Abilities Screening Instrument (CASI), and the clock drawing test.An AMTS score of less than six (out of a possible score of ten) and an MMSE score under 24 (out of a possible score of 30) suggests a need for further evaluation. Scores must be interpreted in the context of the person's educational and other background, and the particular circumstances; for example, a person highly depressed or in great pain will not be expected to do well on many tests of mental ability.

Mini-mental state examination

The U.S. Preventive Services Task Force (USPSTF) reviewed tests for cognitive impairment and concluded:
  • MMSE


sensitivity 71% to 92%
specificity 56% to 96%


Modified Mini-Mental State examination (3MS)

A copy of the 3MS is online. A meta-analysis concluded that the Modified Mini-Mental State (3MS) examination has:
sensitivity 83% to 93.5%
specificity 85% to 90%


Abbreviated mental test score

A meta-analysis concluded:
sensitivity 73% to 100%
specificity 71% to 100%


Duration of symptoms

Duration of symptoms must normally exceed 6 months for a diagnosis of dementia or organic brain syndrome to be made.

Other examinations

Many other tests have been studied including the clock-drawing test ( example form). Although some may emerge as better alternatives to the MMSE, presently the MMSE is the best studied. However, access to the MMSE is now limited by enforcement of its copyright.

Another approach to screening for dementia is to ask an informant (relative or other supporter) to fill out a questionnaire about the person's everyday cognitive functioning. Informant questionnaires provide complementary information to brief cognitive tests. Probably the best known questionnaire of this sort is the Informant Questionnaire on Cognitive Decline in the Elderly .

The General Practitioner Assessment Of Cognition combines both, a patient assessment and an informant interview. It was specifically designed for the use in the primary care setting and is also available as web-based test. It can be accessed on www.gpcog.com.au.

Further evaluation includes retesting at another date, and administration of other (and sometimes more complex) tests of mental function, such as formal neuropsychological testing.

Laboratory tests

Routine blood tests are also usually performed to rule out treatable causes. These tests include vitamin B12, folic acid, thyroid-stimulating hormone (TSH), C-reactive protein, full blood count, electrolytes, calcium, renal function, and liver enzymes. Abnormalities may suggest vitamin deficiency, infection or other problems that commonly cause confusion or disorientation in the elderly. The problem is complicated by the fact that these cause confusion more often in persons who have early dementia, so that "reversal" of such problems may ultimately only be temporary.

Testing for alcohol and other known dementia-inducing drugs may be indicated.

Imaging

A CT scan or magnetic resonance imaging (MRI scan) is commonly performed, although these modalities do not have optimal sensitivity for the diffuse metabolic changes associated with dementia in a patient that shows no gross neurological problems (such as paralysis or weakness) on neurological exam. CT or MRI may suggest normal pressure hydrocephalus, a potentially reversible cause of dementia, and can yield information relevant to other types of dementia, such as infarction (stroke) that would point at a vascular type of dementia.

The functional neuroimaging modalities of SPECT and PET are more useful in assessing long-standing cognitive dysfunction, since they have shown similar ability to diagnose dementia as a clinical exam. The ability of SPECT to differentiate the vascular cause from the Alzheimer disease cause of dementias, appears to be superior to differentiation by clinical exam.

Recent research has established the value of PET imaging using carbon-11 Pittsburgh Compound B as a contrast medium (PIB-PET) in predictive diagnosis of various kinds of dementia, in particular Alzheimer's disease. Studies from Australia have found PIB-PET to be 86% accurate in predicting which patients with mild cognitive impairment would develop Alzheimer's disease within two years. In another study, carried out using 66 patients seen at the University of Michigan, PET studies using either PIB or another contrast agent, carbon-11 dihydrotetrabenazine (DTBZ), led to more accurate diagnosis for more than one-fourth of patients with mild cognitive impairment or mild dementia.

Causes

Fixed cognitive impairment

Various types of brain injury, occurring as a single event, may cause irreversible but fixed cognitive impairment. Traumatic brain injury may cause generalised damage to the white matter of the brain (diffuse axonal injury), or more localised damage (as also may neurosurgery). A temporary reduction in the brain's supply of blood or oxygen may lead to hypoxic-ischemic injury. Strokes (ischemic stroke, or intracerebral, subarachnoid, subdural or extradural hemorrhage) or infections (meningitis and/or encephalitis) affecting the brain, prolonged epileptic seizures and acute hydrocephalus may also have long-term effects on cognition. Excessive alcohol use may cause either alcohol dementia or Korsakoff's psychosis (and certain other recreational drugs may cause substance-induced persisting dementia); once overuse ceases, the cognitive impairment is persistent but non-progressive.

Slowly progressive dementia

Dementia which begins gradually and worsens progressively over several years is usually caused by neurodegenerative disease, that is, by conditions affecting only or primarily the neurons of the brain and causing gradual but irreversible loss of function of these cells. Less commonly, a non-degenerative condition may have secondary effects on brain cells, which may or may not be reversible if the condition is treated.

The causes of dementia depend on the age at which symptoms begin. In the elderly population (usually defined in this context as over 65 years of age), a large majority of cases of dementia are caused by Alzheimer's disease, vascular dementia or both. Dementia with Lewy bodies is another fairly common cause, which again may occur alongside either or both of the other causes. Hypothyroidism sometimes causes slowly progressive cognitive impairment as the main symptom, and this may be fully reversible with treatment. Normal pressure hydrocephalus, though relatively rare, is important to recognise since treatment may prevent progression and improve other symptoms of the condition. However, significant cognitive improvement is unusual.

Dementia is much less common under 65 years of age. Alzheimer's disease is still the most frequent cause, but inherited forms of the disease account for a higher proportion of cases in this age group. Frontotemporal lobar degeneration and Huntington's disease account for most of the remaining cases. Vascular dementia also occurs, but this in turn may be due to underlying conditions (including antiphospholipid syndrome, CADASIL, MELAS, homocystinuria, moyamoya and Binswanger's disease). People who receive frequent head trauma, such as boxers or some martial artists, are at risk of dementia pugilistica. An association between coeliac disease and dementia has been proposed, but this is controversial.

In young adults (up to 40 years of age) who were previously of normal intelligence, it is very rare to develop dementia without other features of neurological disease, or without features of disease elsewhere in the body. Most cases of progressive cognitive disturbance in this age group are caused by psychiatric illness, alcohol or other drugs, or metabolic disturbance. However, certain genetic disorders can cause true neurodegenerative dementia at this age. These include familial Alzheimer's disease, metachromatic leukodystrophy, SCA17 (dominant inheritance); adrenoleukodystrophy (X-linked); Gaucher's disease type 3, Niemann-Pick disease type C, pantothenate kinase-associated neurodegeneration, Tay-Sachs disease and Wilson's disease (all recessive). Wilson's disease is particularly important since cognition can improve with treatment.

At all ages, a substantial proportion of patients who complain of memory difficulty or other cognitive symptoms are suffering from depression rather than a neurodegenerative disease. Vitamin deficiencies and chronic infections may also occur at any age; they usually cause other symptoms before dementia occurs, but occasionally mimic degenerative dementia. These include deficiencies of vitamin B12, folate or niacin, and infective causes including cryptococcal meningitis, HIV, Lyme disease, progressive multifocal leukoencephalopathy, subacute sclerosing panencephalitis, syphilis and Whipple's disease.

Rapidly progressive dementia

Creutzfeldt-Jakob disease typically causes a dementia which worsens over weeks to months. The common causes of slowly progressive dementia also sometimes present with rapid progression: Alzheimer's disease, dementia with Lewy bodies, frontotemporal lobar degeneration (including corticobasal degeneration and progressive supranuclear palsy).

On the other hand, encephalopathy or delirium may develop relatively slowly and resemble dementia. Possible causes include brain infection (viral encephalitis, subacute sclerosing panencephalitis, Whipple's disease) or inflammation (limbic encephalitis, Hashimoto's encephalopathy, cerebral vasculitis); tumours such as lymphoma or glioma; drug toxicity (e.g. anticonvulsant drugs); metabolic causes such as liver failure or kidney failure; and chronic subdural hematoma.

Dementia as a feature of other conditions

There are many other medical and neurological conditions in which dementia only occurs late in the illness, or as a minor feature. For example, a proportion of patients with Parkinson's disease develop dementia, though widely varying figures are quoted for this proportion . When dementia occurs in Parkinson's disease, the underlying cause may be dementia with Lewy bodies or Alzheimer's disease, or both. Cognitive impairment also occurs in the Parkinson-plus syndromes of progressive supranuclear palsy and corticobasal degeneration (and the same underlying pathology may cause the clinical syndromes of frontotemporal lobar degeneration). Chronic inflammatory conditions of the brain may affect cognition in the long term, including Behçet's disease, multiple sclerosis, sarcoidosis, Sjögren's syndrome and systemic lupus erythematosus. Although the acute porphyrias may cause episodes of confusion and psychiatric disturbance, dementia is a rare feature of these rare diseases.

Aside from those mentioned above, inherited conditions which may cause dementia alongside other features include:

Prevention

It appears that the regular moderate consumption of alcohol (beer, wine, or distilled spirits) and a Mediterranean diet may reduce risk. A study has shown a link between high blood pressure and developing dementia. The study, published in the Lancet Neurology journal July 2008, found that blood pressure lowering medication reduced dementia by 13%.

Brain-derived neurotrophic factor (BDNF) expression is associated with some dementia types.

NSAIDs

Non-steroidal anti-inflammatory drugs (NSAIDs) can decrease the risk of developing Alzheimer's and Parkinson's diseases. The length of time needed to prevent dementia varies, but in most studies it is usually between 2 and 10 years. Research has also shown that it must be used in clinically relevant dosages and that so called "baby aspirin" doses are ineffective at preventing and treating dementia.

Alzheimer's disease causes inflammation in the neurons by its deposits of amyloid beta peptides and neurofibrillary tangles. These deposits irritate the body by causing a release of e.g. cytokines and acute phase proteins, leading to inflammation. When these substances accumulate over years they contribute to the effects of Alzheimer's. NSAIDs inhibit the formation of such inflammatory substances, and prevent the deteriorating effects.

Management

Except for the treatable types listed above, there is no cure to this illness, although scientists are progressing in making a type of medication that will slow down the process. Cholinesterase inhibitor are often used early in the disease course. Cognitive and behavioral interventions may also be appropriate. Educating and providing emotional support to the caregiver (or carer) is of importance as well (see also elderly care).

A Canadianmarker study found that a lifetime of bilingualism has a marked influence on delaying the onset of dementia by an average of four years when compared to monolingual patients. The researchers determined that the onset of dementia symptoms in the monolingual group occurred at the mean age of 71.4, while the bilingual group was 75.5 years. The difference remained even after considering the possible effect of cultural differences, immigration, formal education, employment and even gender as influences in the results.

Some studies worldwide have found that Music therapy may be useful in helping patients with dementia.

Medications



Tacrine (Cognex), donepezil (Aricept), galantamine (Razadyne), and rivastigmine (Exelon) are approved by the United States Food and Drug Administration (FDA) for treatment of dementia induced by Alzheimer disease. They may be useful for other similar diseases causing dementia such as Parkinsons or vascular dementia.
  • N-methyl-D-aspartate Blockers. Memantine (Namenda) is a drug representative of this class. It can be used in combination with acetylcholinesterase inhibitors.


Off label

  • Amyloid deposit inhibitors


Minocycline and Clioquinoline, antibiotics, may help reduce amyloid deposits in the brains of persons with Alzheimer disease.



Depression is frequently associated with dementia and generally worsens the degree of cognitive and behavioral impairment. Antidepressants effectively treat the cognitive and behavioral symptoms of depression in patients with Alzheimer's disease, but evidence for their use in other forms of dementia is weak.



Many patients with dementia experience anxiety symptoms. Although benzodiazepines like diazepam (Valium) have been used for treating anxiety in other situations, they are often avoided because they may increase agitation in persons with dementia and are likely to worsen cognitive problems or are too sedating. Buspirone (Buspar) is often initially tried for mild-to-moderate anxiety. There is little evidence for the effectiveness of benzodiazepines in dementia, whereas there is evidence for the effectivess of antipsychotics (at low doses).

Selegiline, a drug used primarily in the treatment of Parkinson's disease, appears to slow the development of dementia. Selegiline is thought to act as an antioxidant, preventing free radical damage. However, it also acts as a stimulant, making it difficult to determine whether the delay in onset of dementia symptoms is due to protection from free radicals or to the general elevation of brain activity from the stimulant effect.

  • Antipsychotic drugs


Both typical antipsychotics (such as Haloperidol) and atypical antipsychotics such as (risperidone) increases the risk of death in dementia-associated psychosis. This means that any use of antipsychotic medication for dementia-associated psychosis is off-label and should only be considered after discussing the risks and benefits of treatment with these drugs, and after other treatment modalities have failed. In the UK around 144,000 dementia sufferers are unnecessarily prescribed antipsychotic drugs, around 2000 patients die as a result of taking the drugs each year.

Services

Adult daycare centers as well as special care units in nursing homes often provide specialized care for dementia patients. Adult daycare centers offer supervision, recreation, meals, and limited health care to participants, as well as providing respite for caregivers.

Prognosis

Severe dementia is frequently complicated by pneumonia, febrile illnesses, and eating problems. Life expectancy is short at 18 months.

Epidemiology

[[Image:Alzheimer and other dementias world map - DALY - WHO2002.svg|thumb|Disability-adjusted life year for Alzheimer and other dementias per 100,000 inhabitants in 2002.


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See also



References

Notes

External links






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