The causes dementia are the death of nerve cells and the breakdown of communication between them resulting from a number of different neurological factors. Among those conditions are:
- Infections affecting the brain, such as AIDs, Lyme disease and other immune disorders
- Metabolic problems
- Endocrine abnormalities (glands that manage hormones such as the thyroid gland)
- Nutritional deficiencies of vitamins B1 and B12
- Adverse reactions to medications
- Subdural hematomas (blood on the surface of the brain)
- Poisoning by lead, other heavy metals and poisonous substances brain tumors
- Anoxia (also called hypoxia, a lack of oxygen in the system)
- Heart and lung problems
- Cigarette smoking and excessive alcohol consumption
Genetic factors are known to be included in the causes of dementia. In some cases, for example Huntington’s disease, the disorder relates to abnormalities in a single gene. In many others, such as Alzheimer’s disease, the causes appear to be associated with the interaction of genes, environmental factors and lifestyle choices. The risk of Alzheimer’s, vascular dementia and some other types also increases with age.
Various other causes of dementia include abnormal proteins and head trauma, but no cause has been determined for some types such as corticobasal degeneration and frontotemporal dementia.