This is a Phase II screening study of lithium carbonate in ALS. The purpose of this study is to find out if lithium carbonate is safe to be used in people with ALS and if it can slow the progression of the disease. Since there is no placebo in this study, all patients will be taking lithium carbonate.

This is a Phase II Screening study. There is no placebo (inactive or 'fake' drug) in this study, meaning that all participants will be taking lithium carbonate. The purpose of this study is to find out if lithium carbonate is safe to be used in people with ALS and if it can slow the progression of the disease.

A recent article was published in a highly regarded medical journal that showed a positive effect of lithium carbonate on an ALS type mouse. The researchers then studied a very small number of people with ALS, giving 16 people lithium carbonate with riluzole and giving 28 people only riluzole. The people who took lithium remained stronger for a considerably longer period of time. However, the study was very small and we cannot really tell if lithium works unless a larger study is performed. It is not well understood why lithium carbonate might be helpful but it is believed that it may play a role in protecting the motor nerves from the damage of ALS.

If you choose to participate, you will need to go to your study clinic for research study visits 7 times in one year and you will have 4 telephone interviews during that time. These visits and phone calls could take up to 17 hours in total.

Caution: Lithium is an FDA approved drug used for some psychiatric disorders. It is not FDA approved for ALS. Lithium has many potentially serious side effects and must only be taken under close supervision of your physician.

Inclusion Criteria:

• Clinical diagnosis of laboratory-supported probable, probable, or definite ALS
• Vital capacity of at least 75% of predicted
• Onset of weakness within 3 years prior to enrollment
• If patients are on riluzole, they must be on a stable dose for at least 30 days prior to baseline visit
• Women of childbearing potential must be surgically sterile or using an effective method of birth control and have a negative pregnancy test
• Willing and able to give informed consent

Exclusion Criteria:

• Diagnosis of other neurodegenerative disease
• Need tracheotomy ventilation or non-invasive ventilation 23 or more hours/day
• Clinically significant history of any unstable medical condition in past 30 days
• History of renal
• History of liver disease
• Current pregnancy or lactation
• Use of lithium within thirty days of enrollment
• Significantly limited mental capacity
• History of recent drug or alcohol abuse
• Use of any investigational drug within 30 days prior to enrollment