MND can develop in adults or children, depending on the type. These diseases are more likelyTrusted Source to affect males than females. Inherited forms may be present at birth. However, MND symptoms are most likely to appear after the age of 50 yearsTrusted Source.
The different types appear to have some different risk factors. SMA, for example, is always hereditary, but this is not true for all forms of MND. Around 10%Trusted Source of ALS cases in the United States are hereditary.
Also, the National Institute of Neurological Diseases and Stroke observes that veterans appear to have a 1.5 to 2.0 timesTrusted Source higher chance of developing ALS than nonveterans. This may indicate that exposure to certain toxins increases the risk of ALS.
In addition, a 2012 studyTrusted Source found that professional football players have a higher risk of dying from ALS, Alzheimer’s disease, and other neurodegenerative diseases, compared with other people. Experts think that this could indicate a link with recurrent head trauma.