A lengthy article concerning the discovery of the toxic by product of cyanobacteria, BMAA, and its potential association with ALS and other neuro degenerative diseases appears in most recent Discover Magazine. the article is not referenced online yet (that I can find). I recall information concerning the neurotoxicity of cyanobacteria more than a decade ago, though these articles mark recent interest into the possibility of implicating BMAA toxin in ALS cases.
http://tpwmagazine.com/archive/2009/july/scout5/

Flora Fact: Blue-Green Mystery
Sometimes found in Texas lakes, cyanobacteria may be the cause of several diseases, but new research could lead to a cure.
By Wendee Holtcamp
... Biologists at the Institute for Ethnomedicine, led by Director Paul Alan Cox, believe they’ve found the culprit for ALS (Lou Gehrig’s disease) and other “tangle diseases” including Alzheimer’s, Parkinson’s disease and supranuclear palsy. The tiny neurotoxic molecule BMAA (β-N-methylamino-L-alanine) is produced by blue-green algae (also called cyanobacteria) found worldwide. The good news? The discovery could lead to a cure. The bad news? BMAA in drinking water could be a health risk even at low levels, but no one’s testing for it in water supplies yet.

In the Discover article, Dr. Deborah Mash, professor at Univ of Miami Med School, is identified as a researcher into the possibility that BMAA causes neurodegenerative diseases. She is also a primary researcher on "Ibogaine" an orally administered substance used to increase GDNF and treat addictions; seems the oral form crosses the BBB.
from former posting on Ibogaine:
"...In a recent study, ibogaine was
found to upregulate GDNF expression in the midbrain and increase GDNF
secretion and GDNF-dependent activation of downstream signaling pathways in vitro (4). These data suggest that ibogaine may represent a powerful new
method to upregulate GDNF in the treatment of neurodegenerative disorders.
Multidisciplinary research, using ibogaine as a lead compound, could reshape
the lives of those afflicted with Parkinson’s Disease..."

http://neurotalk.psychcentral.com/sh...ional+medicine

The use of Ibogaine is currently in clinical trials for the treatment of addictions, esp alcoholism. seems it is on no one's radar for potential use in PD(the above abstract is from a student's proposal). The researchers I corresponded with about the use of Ibogaine and its utility in PD both commented that due to its hallucinatory potential, it would probably not be used for PD. OH? as though many approved PD drugs do not have that potential. Seems a major problem with studying this drug is that it is a naturally occurring plant product and thus not patentable. hopefuly some pharma co will become interested and extract the active substrate and synthesize it. thus making it patentable.