Week 3: What are the causes of dementia?

Many diseases can cause dementia, including Alzheimer's disease, vascular dementia, Lewy Body disease, head trauma, frontotemporal dementia, Creutzfeldt-Jakob disease, Parkinson’s disease, and Huntington’s disease. These conditions can have similar and overlapping symptoms. In spite of these similarities, the cause of the dementia may have effects on the treatment and outcome of the illness. It is therefore always important to ensure your physician has investigated the possible causes of the dementia. 

Alzheimer's Disease

A slowly progressive brain disease that begins well before symptoms emerge, due to deposits of the protein fragment beta-amyloid (plaques) and twisted strands of the protein tau (tangles), as well as evidence of nerve cell damage and death in the brain. 

Vascular Dementia

Vascular dementia was previously known as multi-infarct or post-stroke dementia. It occurs from cerebrovascular disease which can include blood vessel blockage or damage leading to infarcts (strokes) or bleeding in the brain. The location, number, and size of the brain injury determine how the individual's thinking and physical functioning are affected.  

Dementia with Lewy Bodies

Lewy bodies are abnormal aggregations or clumps of the protein alpha-synuclein. When they develop in a part of the brain called the cortex, dementia can result. Alpha-synuclein also aggregates in the brains of people with Parkinson's disease, but these aggregates may appear in a pattern that is different from dementia with Lewy bodies. 

Mixed Dementia

In mixed dementia, abnormalities linked to more than one cause of dementia occur simultaneously in the brain. The most common type of mixed dementia is Alzheimer’s disease and cerebrovascular disease.  

Parkinson's Disease Dementia

Best known for the movement problems it causes, Parkinson’s disease can also be associated with a specific type of dementia. Alpha-synuclein clumps are likely to begin in an area deep in the brain called the substantia nigra. These clumps are thought to cause degeneration of the nerve cells that produce dopamine. 

Frontotemporal Dementia

Frontotemporal dementia includes a variety of different dementia syndromes such as behavioral variant, primary progressive aphasia, Pick's disease, corticobasal degeneration and progressive supranuclear palsy. Many different microscopic abnormalities are linked to the various cases. 

Creutzfeldt-Jakob disease (CJD)

CJD is the most common human form of a group of rare, fatal brain disorders affecting people and other mammals. Variant CJD (“mad cow disease”) occurs in cattle, and has been transmitted to people under certain circumstances. The disease which can arise spontaneously, be inherited, or result for infection is caused by misfolded proteins called prions. 

Normal Pressure Hydrocephalus

Caused by the abnormal buildup of fluid in the brain. It causes the characteristic features of dementia, gait disturbance and urinary incontinence. It is potentially treatable with surgery.

Huntington's Disease

A progressive brain disorder caused by a single defective gene on chromosome 4. The gene defect causes abnormalities in a brain protein that, over time, leads to a movement disorder and dementia. 

Wernicke-Korsakoff Syndrome

Korsakoff syndrome is a chronic memory disorder caused by severe deficiency of thiamine (vitamin B-1). The most common cause is alcohol abuse. Thiamine helps brain cells produce energy from sugar. When thiamine levels fall too low, brain cells cannot generate enough energy to function properly.  

Others

Other cases of dementia may be related to:

·     Drugs (including certain prescription drugs, over the counter drugs, and illicit drugs)

·     Brain tumors

·     Thyroid disease

·     Depression