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Abstract
Dementia is defined as a decline in a person`s ability to think and learn . To distinguish true dementia from more limited difficulties due to localized brain damage , the strict medical definition requires that this decline affects at least two distinict spheres of mental activity , Examples of such spheres include memory , verbal fluency , calculating ability and understanding of time and location .
The first step in diagnosing dementia is to show that the person`s ability to think and learn has , in fact , declined from its earlier level . His or her current ability in different spheres of mental activity can be measured by any of a variety of mental status tests. The difficulty comes in comparing these current ability levels with those at earlier times . A patient`s own reports cannot be relied upon , since memory loss is typically part of dementia . Frequently , however , family members` descriptions of what the person once could do , will establish that a decline has occurred . In other cases , comparison with what a person has accomplished throughout his or her life is enough to show that a decline has occurred . If neither sources of information provides a clear answer , it may be necessary to readminister the mental status test several months later and compare the tow results .
A number of infections that affect the central nervous system have been known to cause dementia symptoms .
Researches have established a link between infectious diseases such as Prion Diseases and HIV and the onset of dementia . Dementia may also be caused by a number of other infectious viruses , bacteria , disease-carrying parasites and fungi. Infectious diseases can cause neurological damage with symptoms such as confusion , delirium , memory loss and other dementia-related symptoms .
Prions (proteinaceous infectious particles) are the proteins responsible for a groub of infectious diseases know as TSEs (transmissible spongiform encephalopathies) , which include Creutzfeldt-Jakob disease , BSE (Bovine spongiform encephalopathy or mad cow disease) and Scarpie (an infectious disease contracted from sheep) . All these infectious diseases have in common neural cell death caused by defective prion proteins .
Prions are infective proteins . They act somewhat like viruses but do not possess any DNA or RNA material .
In humans , prion diseases can occure in one of several forms:
1. Creutzfeldt-Jakob Disease (CJD) : Creutzfeldt-Jakob disease is a rare progressive neurological disorder for which no cure has yet been found . Dementia in CJD patients involves neural cell death caused by prions .
2. Kuru Disease : It has been reported in tribes people in Papua New Guinea , who had practiced cannibalism , and therefore were directly exposed to a deceased person`s diseased brain tissue .
3. Gerstmann-Straussler-Scheinker Syndrom (GSS) : Is similar to CJD but lasts for more than 2 years .
4. Fatal Familial Insomnia (FFI) : It is an atypical prion disease characterized by degeneration of the thalamus and hypothalamus , leading to insomnia and dysautonomia .
5. Alpers Syndrome : Prion disease occurring in children .
HIV dementia is a specific type of dementia found in patients with late stage HIV/AIDS . The disease is also called ADC (AIDS dementia complex) . HIV can cause healthy brain cells to break down , releasing damaging enzymes . These enzymes then attack healthy neurons , causing dementia symptoms . Dementia is a common complication of HIV . Over 20% of HIV patients develop some symptoms of dementia . HIV clinical trials are testing medication that may block the neuron damaging action of the released enzymes . Research into the causes and possible treatments for HIV associated dementia is still in its infancy . Further researches are required to establish the pattern of neural cell death that differentiates HIV associated dementia from other similar infectious diseases .
It is important to differentiate between HIV associated Dementia & Delirium (which is considered as a preparatory stage before ADC ) .
Other infectious diseases causing dementia :
1. Progressive Multifocal Leukoencephalopathy : is caused by the JC virus . This virus can cause nerve cell damage , leading to confusion , psychiatric problems and speech problems .
2. Subacute Sclerosing Panencephalitis : It is a rare chronic , progressive encephalitis that affects primarily children and young adults , caused by a persistent infection of immune resistant measles virus .
3. General Paresis of Insane : a brain disease associated with the advanced stages of syphilis due to irreversible damage to the nervous system .
4. Lyme disease : a progressive infectious disease caused by the bacterium Borrelia burgdorferi, transmitted by tick bites .