Rare Dementia Diseases

Korsakoff's Psychosis

Korsakoff's Psychosis is a chronic dementia disease where the patient has pronounced memory disorders. It is caused by damage to the brain's deep structure as a result of thiamine deficiency. This deficiency is almost exclusively observed in alcoholics. They initially develop an acute brain disease (Wernicke's syndrome) with confusion, memory failure, walking impairment and eye muscle paralysis. If the condition is not treated, it develops into a chronic dementia disease with pronounced memory disorders (Korsakoff's psychosis).

The memory becomes full of "lapses", and the sick person often unconsciously fills the memory lapses with explanations or stories that sound plausible (called ‘confabulation’). The condition normally does not deteriorate once the acute state has passed. For other effects of alcohol, also read here.

Hereditary Dementia Diseases

Certain dementia diseases are hereditary. The hereditary frequency of the diseases depends upon the type of dementia involved.

For frontotemporal dementia up to 40 % is hereditary; unfortunately, only a few of the genes are known to date.

For Alzheimer's disease only a few percent is hereditary. Three different hereditary characteristics are known today with many different changes (mutations).

For vascular dementia there are also rare hereditary forms.

Finally there are rarer hereditary brain diseases such as Huntington's Chorea.

Huntington's Chorea

Huntington's Chorea is a typically hereditary disease where the gene is located on Chromosome 1. During Huntington's disease there is often a mixture of neurological and psychiatric symptoms, frequently including dementia, in the late stages. The symptoms may vary individually; however, there are normally differing degrees of involuntary spasmodic movements (chorea), wobbling gait and possibly progressive muscular spasticity (dystonia). Dementia is not observed in everyone. It develops slowly and not until late in the course of the disease. Hallucinations and depression may also occur.

The diagnosis is normally made based on the symptoms and the knowledge that there is a history of the disease in the family. A blood test can reveal if a person has the gene for Huntington's disease

Space-Occupying Lesions

Dementia may also, in rare cases, be caused by tumors or fluid accumulations in the brain. These may be benign or malignant tumors,  cysts or an elevated fluid level in the brain cavity (ventricles).

Normal Pressure Hydrocephalus (NPH)

During normal pressure hydrocephalus the fluid produced in the brain cavity (ventricles) has a difficult time being reabsorbed. That causes the brain cavity to expand.

That causes symptoms of dementia and, the person also experiences walking impairment and bladder trouble (incontinence). The three symptoms (dementia, walking impairment and incontinence) are all present early in the course of normal pressure hydrocephalus.

Doctors suspect the disease when a brain shows that the fluid cavities (ventricles) are expanded. The doctors make the diagnosis by measuring how quickly the brain fluid can be absorbed.

The disease is treated by placing a plastic drain (shunt) in the brain fluid cavity. The treatment normally has a good effect on the walking impairment and incontinence. The treatment is often not as effective on the memory disorders.

Inflammatory causes

Inflammation of the brain may be due to viral or bacterial infections.

Viral or Bacterial Infections

In some cases, dementia can also occur as a result of serious inflammation of the brain or the lining of the brain. It can be caused by bacteria or viruses. Four different types are listed here in alphabetical order. All of these diseases usually have a rapid course.

AIDS Dementia

AIDS dementia is rare today due to improvements in treatment.

Creutzfeldt-Jakob Disease

Eating meat infected with "mad cow" can lead to Creuzfeldt- Jakob like disease. Creutzfeldt-Jakob disease (CJD), is a dementing disease of the brain. Symptoms of CJD include forgetfulness, nervousness, jerky trembling hand movements, unsteady gait, muscle spasms, chronic dementia, balance disorder, and loss of facial expression. CJD is classified as a spongiform encephalopathy. Most cases occur randomly (sporadically), but inherited forms exist.

Herpes Encephalitis
Herpes can in rare instances cause inflammation of the brain. When the herpes virus causes inflammation of the brain, it also affects the frontal lobes and may damage the ability to learn new things. That means that the memory up to the onset of the disease may be intact. The longer the person has the disease, the longer the timeframe will be where the person cannot remember anything.

Syphilis

Syphilis was a frequent cause of dementia in the past. Today the disease is rare, but does still occur. It is normal for the doctor, as part of the examination for dementia, to test for syphilis.

Inflammations

Multiple sclerosis is a disease where the body has a reaction to infection (inflammation) that destroys the insulation around the nerve fibers. Multiple sclerosis can result in dementia-like changes.

There are also rare inflammatory diseases that may affect the brain and cause dementia.

Poisoning

Certain heavy metal poisonings, including lead and mercury, and long-term exposure to organic solvents may lead to memory and concentration failure and dementia. If it is what is called solvent dementia (Painter's Syndrome), the condition stabilizes as soon as the person is no longer exposed to the organic solvents.

Metabolic Diseases

These diseases are rare causes of dementia. For example, disorders of the thyroid or parathyroid glands, high calcium, vitamin deficiencies such as Vitamin B₁ and B₁₂, for example, either due to the person getting too few vitamins in their diet or the vitamins not being absorbed by the body.