In a small number of ALS patients, immune reactions to components of the body’s own nerves can be found. These involve antibodies that react with surface structures of neurons and their axons (anti ganglioside autoantibodies, anti calcium channel autoantibodies).

However, further investigations have shown that the autoantibodies are also present to the same or greater degree in other diseases so that a causal significance of these immune reactions cannot be assumed in ASL. There is also no other evidence of a disorder of immunological functions.

Different investigations on the possible role of a viral infection in ALS have not yielded any confirmation of the hypothesis. The significance of the poliomyelitis virus and other enteroviruses was analysed particularly intensely as there are clinical parallels with ALS when motor nerve cells are affected by the poliomyelitis virus. In 2001 an article published in the American journal NEUROLOGY led to renewed discussion of a causative role of viral infections in ALS. In this publication 7 patients were reported who had the immune deficiency disease AIDS and at the same time had motor symptoms with similarities to ALS. This demonstrated again that a viral infection can lead in principle to a motor disease. However, these findings have considerable limitations, which do not allow the viral hypothesis to be applied uncritically to ALS. Thus, the motor disease associated with AIDS has a much more rapid course than in the typical form of ALS. At the same time, specific therapy of the HIV infection leads to a reduction and partial reverse of the motor symptoms – a feature than has not so far been described for typical ALS. Because of the reversibility of the motor symptoms in AIDS, it can be assumed that there is dysfunction of the motor nerve cells. We find a different situation in ALS, which is characterised by slow decline and finally loss of motor neurons. Overall there is currently no evidence that the typical form of ALS is caused by infections with the HI virus or other viruses. Accordingly, the use of antiviral medications is not justified outside controlled clinical studies.