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The disease resembles amyotrophic lateral sclerosis (ALS) (more commonly known in North America as Lou Gehrig's disease), Parkinson's disease, and Alzheimer's. First reports of the disease surfaced in three death certificates on Guam in 1904. These death certificates made some mention of paralysis. The frequency of cases grew amongst the Chamorro people on Guam until it was the leading cause of death between 1940 and 1956. The symptoms range from strongly resembling ALS to those resembling Parkinson's dementia complex (PDC). The symptoms tend to show themselves between the ages of 25 and 40. Many victims are not able to speak of their own accord, but they can speak coherently and fluidly when spoken to.
Neurologist Oliver Sacks detailed this mysterious condition in his book The Island of the Colorblind . Sacks wrote that a local species of fruit bat, which is now largely extinct due to overhunting, had been feeding on cycads and concentrating β-methylamino-L-alanine (BMAA), a known neurotoxin, in its body fat. The hypothesis is that consumption of the fruit bat transferred sufficient quantities of the toxin to lead to long-term toxicity, although this has not yet been proven. However, decline in consumption of the bats has been linked to a decline in the incidence of the disease.
Lytico-bodig disease presents itself in two ways:
- lytico is a progressive paralysis that resembles ALS (amyotrophic lateral sclerosis), which is a disease of the neurons.
- bodig is a condition resembling parkinsonism with occasional dementia.
Patients can exhibit one or both portions of the disease, but to understand this neurodegenerative phenomenon, one must examine the history of the disease itself and the people who are affected.
Lytico-bodig was discovered in 1952 by Koerner and a year later was confirmed by Arnold. The study that led these two scientists to discover it was peculiarly notable on the island of Guam. Both scientists noted a 50- to 100-fold greater occurrence of amyotrophic lateral sclerosis than the rest of the world, and a notable increase in parkinsonism with dementia.
The Chamorro people commonly found to have this disease were native to Guam. Guam has undergone several serious events over the course of its history. In 1668, a near genocide of the Chamorros was started; by 1710, almost no Chamorros remained on the island. The island was handed over to the United States government in 1898, and after World War II, it was retaken from the Japanese by American forces. After these hardships, the Chamorros survived and their living situation improved.
Documentation of anything that could resemble lytico-bodig was lacking in the entire history of the Chamorros. They were actually described as a very healthy people who lived to old ages. Until 1904, no cases of death from paralysis had been reported to have occurred, but by 1940, this elusive paralysis was the primary cause of death in an adult Chamorros.
No standard form of bodig is reported; it can take three, six, or 20 different forms.
The symptoms for this disease differ from patient to patient, but a good example of what happens to the body once it sets in is an excerpt from the book The Island of the Colorblind by Oliver Sacks.
The doctor visited a patient who had just suddenly come down with a virulent form. His symptoms had begun 18 months before, starting with a strange immobility and a loss of initiative and spontaneity; he found he had to make a huge effort to walk, to stand, and to make the least movement—his body was disobedient. The immobility attacked with frightening speed, and within a year, he was unable to stand alone and could not control his posture (2006).
Progressive dementia is also characteristic of bodig. Those who experience dementia are often aphasic, restless, and demonstrate irrational behavior, such as violence, and deep emotions at odd intervals. They experience highs and lows, such as giggling one minute and screaming the next.
Patients in the most virulent stage have mouths hanging open, drooling with saliva; their tongues hang motionless, so speech and swallowing are impossible. The arms and legs become severely spastic and bent in immovable tension.
The clinical picture of bodig was often one of a profound motionlessness, almost catatonia, accompanied with a little tremor or rigidity. Except in the cases of those who have dementia coupled with bodig, most patients are capable of lucid thought and speech.
As with bodig, the symptoms and forms of lytico present themselves differently from patient to patient.
Symptoms such as muscles wasting away, not being able to move or open the mouth to speak, and choking to death because of the inability to swallow are just some of the symptoms prevalent in patients. Some patients retain lucidity throughout the illness until the end.
The muscles of respiration become paralyzed and mechanical ventilation is needed to induce breathing, saliva must be suctioned from the mouth to prevent aspiration of the trachea and lungs because the swallowing muscles are locked up.
This form of lytico-bodig is fatal in all cases.
The following is an excerpt from Island of the Colorblind viewing samples of substantia nigra. "Many of the cells are pale and depigmented. There's a lot of glial reaction, and bits of loose pigment. Shifting to a higher power, he saw a huge number of neurofibrillary tangles, densely staining, convoluted masses, harshly evident within the destroyed nerve cells." Looking at other samples of hypothalamus, spinal cord, and cortex, all were full of neurofibrillary tangles. Neurofibrillary degeneration was everywhere. These slides were similar in appearance to those taken from postencephalitic parkinsonism.
These slides were also very similar to the neurofibrillary tangles found in Alzheimer's disease; however, in Alzheimer's, fewer tangles occur, and in a different distribution. This could be a possible clue as to the process of neurodegeneration, but it is still inconclusive.
While neurofibrillary degeneration is a potential cause of lytico-bodig, much is still undiscovered as to what causes the symptoms, the severity, and how the onset of symptoms progresses. Similar symptoms of postencephalitic patients and Alzheimer's patients could account for the similarities in symptoms of lytico and bodig. Some even wonder if lytico-bodig, postencephalitis, and Alzheimer's could possibly be the same disease, a viral one, which could take three different forms.
Age of onset seems to be increasing with no more teenage cases and almost no cases in their twenties. Sometimes, one form of the disease will present itself chiefly in one decade and then another form predominates in the next.
No treatment has been found to cure lytico-bodig. In some cases, L-dopa was given to patients to alleviate some of the symptoms of bodig, but this only gave the patients one or two hours of freedom from the complete paralysis and rigidity of limbs. It seems in the case of the Chamorros, family members are the primary caregivers, and they have accepted those who are ill and provide home care for all those inflicted with lytico-bodig.
Some hypotheses as to the cause of the disease include genetics, cycad seeds, and ingested beta-Methylamino-L-alanine (BMAA) from the consumption of fruit bats. The actual cause of the disease is as mysterious as the vast manifestations of the disease itself.
- Genetics was first hypothesized due to the situation on Guam. Lytico-bodig was found in great numbers among members of the Chamorro community, so genetic factors were possible. It was the first to be disproved; only the older generation of Chamorro had the disease, and it had disappeared in one generation. Also, Chamorro who grew up outside of Guam had not developed the disease, and some non-Chamorro who moved to the island and followed the culture did develop it. Therefore, this hypothesis was quickly dropped.
- Cycad seeds are a big part of the Chamorro lifestyle. They are ground to make a flour called fadang, and the flour is then used to make flatbread and dumplings. The flour is soaked and cleaned several times because the seed in its natural form is extremely toxic. One article described livestock that drank from the water of the first cleaning dropping dead instantly. Ample research on the cycad hypothesis found a component of the seeds, cycasin, was a potent toxin; it was discovered in the 1950s. As toxic as it was, it would not be the cause of the symptoms of lytico-bodig. British biochemists discovered another toxic substance in the seeds, BMAA (beta-Methylamino-L-alanine), in the 1960s. Experiments were performed to test its toxicity; when monkeys were fed synthetic BMAA, they developed symptoms of ALS-PDC and thus of lytico-bodig. The treated flour was tested for BMAA, and was not found to contain sufficient quantities, but this analysis may have been mistaken. A later analysis did find significant levels of toxin in fadang, and found also that the levels were higher in fadang made at settlements with a higher incidence of lytico-bodig.
- Another theory was introduced by Paul Alan Cox and Oliver Sacks after examining aspects of the Chamorro diet. Fruit bats, which often ate cycad seeds, were a common food for the Chamorros. The bats bioaccumulate BMAA in their fat, and eating even a few bats would cause a dose of BMAA similar to levels that produced disease symptoms in the earlier animal models. Cox also observed decline in fruit bat consumption matching the decline in lytico-bodig. This hypothesis is still being investigated. 
The actual disease could be eliminated before a cure is found, since only the older generation of people on Guam have it, and the cause has not yet been found.
Lytico-bodig is isolated to Guam which makes it an excellent opportunity to research neurodegenerative diseases. If a cure were found, it could lead to significant information on other diseases, such as Parkinson's and Alzheimer's. Only time and future research will tell the outcome of the disease.
- β-Methylamino-L-alanine (BMAA)
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