Possible Early Dementia Causes

We do not know exactly what causes MCI. We do know that most people with MCI eventually develop Alzheimer disease. Like Alzheimer disease, MCI is thought to be linked to abnormal deposits of certain proteins in the brain. Having low levels of certain brain chemicals called neurotransmitters is another feature of MCI and Alzheimer disease.

A small number of cases of MCI are related not to Alzheimer disease but to other causes of dementia. These include stroke, Parkinson disease, head injury, depression or extreme stress, drug interactions or side effects, or other medical conditions such as liver diseases or hormone disturbances. The number of conditions that can result in MCI and dementia is large.

The speed with which symptoms develop is often a clue to the cause of the MCI. MCI related to Alzheimer disease develops gradually in most cases. MCI of some other causes may develop more quickly.