Motor neurone disease does not show many symptoms, making it very hard to diagnose. It usually affects people ages 40-60. The earliest symptoms may include twitching, cramping, or stiffness of muscles; muscle weakness affecting an arm or a leg; slurred and strange-sounding nasal speech; or having a difficult time chewing or swallowing. These general symptoms then develop into clear weakness or atrophy that may cause a physician to believe that a person has ALS.