In many patients mitochondrial disease leads to progressive nerve and muscle damage that may be associated with problems with thinking, talking, remembering, walking or balancing. Sometimes it may also cause abnormal build up in the blood and spinal fluid of a substance called lactic acid. This problem makes the blood and spinal fluid too acid, which can be life-threatening. There is no known specific or effective treatment for mitochondrial diseases. Sometimes certain diets can improve the condition but seldom prevent the nerve or muscle damage or reduce the chance of developing life-threatening acidity of the blood.