You cannot prevent ALS, since the cause of the disease is unknown. Should scientists find more about the genetic basis of ALS in the future, there could be a chance of a prenatal diagnostics.
The average life expectancy of ALS patients is three and a half years after the diagnosis. A third of the patients survive five more years or even longer. Exact statements are not possible because of the different progressions of the disease. Because of the often rapid progress of ALS, after the diagnosis, doctors advise patients to quickly issue a living will and a guardianship power of attorney.
Prompt psychological assistance is also recommended. Besides the doctors, ALS self help groups offer support. In case of an early diagnosis and early treatment, a really high life expectancy is possible for many patients. Depressions and anxiety disorders occur relatively rarely. In case of good care at the patient’s home, treatment at the hospital only becomes necessary in a later stage of the disease.