Re: Re: Causes of ALS

[Guest guest]

== Reasonable and viable hypotheses all, for all or part of the phenomenon

that's ALS. Of course, these don't preclude others.

Longstreth et al.8 summarized hypotheses that

might explain the role of athletics. Vigorous physical

activity might increase exposure to environmental

toxins, facilitate the transport of toxins across the

blood�brain barrier, increase the absorption of a

toxin by the lower motor neurons, or increase susceptibility

of motor neurons supplying fast-twitch fibers

by stressing activity. For example, poliovirus seemed

to affect limbs that had been exercised at the time of

infection.9 Alternatively, being slim and athletic might

be a phenotypic expression of genetic susceptibility to

ALS, mediated by some environmental agent.