Infectious Diseases and Dementia

Researchers have established a link between infectious diseases such as HIV and Creutzfeldt-Jakob 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.

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) or HAD (HIV-associated dementia).

Research into the causes and possible treatments for HIV-associated dementia is still in its infancy. Further research is required to establish the pattern of neural cell death that differentiates HIV-associated dementia from other similar infectious diseases.

These are basic facts associated with HIV dementia:

The first signs of HIV-associated dementia include:

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 proteins called prions. CJD is one of a group of dementia-related infectious diseases called subacute spongiform encephalopathies.

The incidence of CJD is approximately one in a million people per year. Although it's one of the rarer types of infectious diseases, CJD can strike at any age, with the average onset occurring between 50 and 65 years of age. CJD is rare among people under the age of thirty, with fewer than five per billion people in this age group dying from the disease in the US.

 

 

CJD Symptoms: Dementia-related symptoms of CJD include:

Diagnosis of CJD: Creutzfeldt-Jakob disease is diagnosed using an electroencephalogram (EEG), which records the electrical activity of the brain. Other methods of diagnosis involve a biopsy of the tonsils or brain tissue.

Prognosis for CJD: Death is expected within a few months following transmission of corrupted prion proteins. Life expectancy is approximately six to twelve months, with some patients living up to 24 months. The median survival rate is four months following the onset of symptoms.

Variant Creutzfeldt-Jakob disease (also called new variant Creutzfeldt-Jakob disease or nvCJD) differs from CJD in that early onset is typically in the twenty-to-thirty age group and the patient exhibits mainly psychiatric symptoms.

Other infectious diseases associated with dementia include:

Gerstmann-Sträussler-Scheinker Disease: Gerstmann-Sträussler-Scheinker disease is similar to Creutzfeldt-Jakob disease, as neuronal cell death and dementia are caused by the presence of defective prion proteins. Symptoms include cognitive impairment and inability to coordinate voluntary movements. Gerstmann-Sträussler-Scheinker is more common in younger age groups.

Syphilis: Syphilis is a sexually transmitted infectious disease caused by the bacterium Treponema pallidum. Untreated syphilis can cause irreversible damage to the nervous system, leading to dementia and death.

General Paresis: General paresis is a type of neurosyphilis, a brain disease associated with the advanced stages of syphilis. Symptoms include muscle wasting, paralysis and common dementia-related symptoms such as tremors and cognitive impairment. General paresis affects mainly the population of Third World countries.

Lyme Disease: Lyme disease is a progressive infectious disease caused by the bacterium Borrelia burgdorferi, transmitted by tick bites. Lyme disease can cause memory loss and cognitive impairment.

Meningitis/Encephalitis: Meningitis and encephalitis are infectious diseases that affect the brain cells. Symptoms include confusion, memory loss, general cognitive impairment, impassivity and, in severe cases, the onset of sudden dementia.

PML (Progressive Multifocal Leukoencephalopathy): Patients with depressed immune systems sometimes develop an infectious disease called PML, which is caused by the JC virus (so named using the initials of the first person from which the virus was isolated). This virus can cause nerve cell damage, leading to confusion, psychiatric problems and speech problems.

 

Resources

Beers, M.H. & Berkow, R. (ed). Antiviral drugs for HIV infection. The Merck Manual of Diagnosis and Therapy, 17th Edition. Merck Research Laboratories, NJ, 1999.

Beers, M.H. & Berkow, R. (ed). Dementia. The Merck Manual of Diagnosis and Therapy, 17th Edition. Merck Research Laboratories, NJ, 1999.

National Institute of Neurological Disorders and Stroke. (nd). Research on mechanisms in HIV dementia and other CNS diseases encouraged.

National Institute of Neurological Disorders and Stroke. (2005). The dementias: Hope through research [NIH Publication No. 04-2252].

Ohio State University Medical Center. (nd). Lyme disease.

Sahai-Srivastava, S. & Jones, B. (2004). Dementia due to HIV disease.