Lytico-bodig, sometimes spelled Lytigo-bodig is the Chamorro word for amyotrophic lateral sclerosis-parkinsonism-dimentia (ALS-PDC), a neurological disease of uncertain etiology that exists in the United States territory of Guam.
The disease resembles Amyotrophic Lateral Sclerosis (ALS), 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 adult death between 1945 and 1956.
Neurologist Oliver Sacks detailed this disease in his book The Island of the Colorblind . Sacks and Paul Alan Cox subsequently wrote that a local species of flying fox, 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 suggests that consumption of the fruit bat by the Chamorro exposed them to BMAA, contributing to or causing their condition. Decline in consumption of the bats has been linked to a decline in the incidence of the disease.
Lytico-bodig was discovered in 1945 by Zimmerman and was later confirmed by Arnold. 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. By 1940, this elusive disease was the primary cause of death in an adult Chamorros.
Lytico-bodig disease presents itself in two ways:
- lytico is a progressive paralysis that resembles ALS (amyotrophic lateral sclerosis)
- bodig is a condition resembling parkinsonism with occasional dementia.
As with bodig, the symptoms and forms of lytico present themselves differently from patient to patient.
Patient presentations include muscle atrophy, maxillofacial paralysis, inability to speak or swallow and subsequent choking. Some patients retain mental lucidity throughout the illness until death, much like ALS patients.
Diaphragm and respiratory accessory muscles can become paralyzed necessitating mechanical ventilation to facilitate breathing. Saliva must be suctioned from the mouth to prevent aspiration. This form of lytico-bodig is fatal in all cases.
No standard form of Bodig has been reported and the documented cases of the disease manifested in many different clinical presentations.
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).
—Oliver Sacks, The Island of the Colorblind, Vintage Books, 1996
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. Patients experience manic highs and lows; giggling one minute and screaming the next.
Patients in the most virulent stage present with mouths hanging open, excessive salivation; their tongues hang motionless rendering speech and swallowing impossible. The patient’s arms and legs become severely spastic and bent in immovable tension.
The advanced progression presents as profound motionlessness, catatonia, accompanied with tremors or rigidity. Except in cases with concurrent dementia, most patients are capable of lucid thought and speech throughout the disease’s physical progression.
The following is an excerpt from Island of the Colorblind, in which samples of substantia nigra are viewed under microscope. "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.
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 Parkinsonism patients and Alzheimer's patients could account for the similarities in symptoms of lytico and bodig. Lytico-bodig, postencephalitis, and Alzheimer's could possibly be the same disease which could take three different forms.
Age of onset seems to be increasing with no more teenage cases and almost no patients in their twenties. Presentation also varies between years. 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.
- 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. The disease was shown to be familial but not genetic. 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.
- The starch from cycad seeds are consumed in the traditional Chamorro diet. The seeds 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 as the seed in its natural form is extremely toxic. 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. Initial laboratory results found low levels of free BMAA in cycad flour. Further laboratory analysis which included protein-bound BMAA found significant levels 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.
- β-Methylamino-L-alanine (BMAA)
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