In particular, John observed, he began to see increasing numbers of elderly people, women especially, who had severe memory disturbances, amnesic syndromes, without any dementia; catatonia without parkinsonism (like Estella); dementia without parkinsonism (like her sister-in-law); arousal disorders (like Euphrasia); or unclassifiable syndromes (like Juan’s), novel forms of the disease never described before.
John was still excited by the mineral hypothesis, and he wanted to pursue it, to gather more conclusive evidence. He invited an old friend and colleague from Toronto, Donald Crapper McLachlan (a neurologist and chemist who had shown elevated levels of aluminum in Alzheimer’s brains as far back as 1973), to join him on Guam, and working with colleagues from the University of Guam, they compared soil samples from Umatac with soil from fifty-five other sites on Guam and reexamined mineral levels in samples of well water all over the island.
Their results, to their surprise, differed greatly from Gaj-dusek and Yase’s – indeed it seemed that the one water source in Umatac, the Piga spring, which the early investigators had found to have low calcium, was quite atypical. Every other water source and all the soils they sampled had high levels of calcium, as might be expected on a limestone island. Further analysis of the soils and of vegetables grown in them found adequate levels of calcium and magnesium and normal levels of aluminum, which seemed to shake the notion of a mineral deficiency or aluminum excess as the cause of lytico-bodig (without, however, excluding it completely).
John is of a passionate disposition and tends to get strongly invested in theories and ideas. He had a huge respect for Gaj-dusek’s intuition, and was greatly taken by the mineral hypothesis; John had hoped to confirm, and perhaps elucidate, this with his own investigations. He had been elated by these hopes, and the promise of Gajdusek and Yase’s hypothesis – and now, suddenly, all this had collapsed. He was back to where Kurland had been a decade earlier, in a conceptual void.
Then, in 1986, his eye was caught by a letter in the Lancet which resurrected the cycad hypothesis. Peter Spencer, a neurotoxicologist, using a purified form of the amino acid BMAA from cycad seeds, found that it could induce a neurological syndrome in monkeys, conceivably analogous to human lytico.
Spencer’s work in this realm went back to the 1970s, when, with his colleague Herb Schaumburg, he had travelled to India to investigate the neurolathyrism there. It had been known for centuries that a spastic paralysis of the legs could follow continued eating of the chickling pea; that this was due to the neurotoxic amino acid BOAA, which damaged the cortical motor cells and their descending connections in the spinal cord, had been known since the 1960s. Spencer’s new studies made clear how BOAA heightened sensitivity to glutamate, one of the neurotransmitters involved in the motor system, and simulated its action as well. BOAA intoxication, therefore, could push the glutamate receptor cells into a sort of overdrive, until they literally died of overexcitation and exhaustion. BOAA was an ex-citotoxin – this was the new term. Could BMAA, he wondered, so similar in structure to BOAA, also act as an excitotoxin and produce a disorder like lytico?
There had been attempts to induce such disorders in animal experiments during the sixties, but the results were inconclusive, and this line of research had been dropped. Now, using cynomolgus monkeys and repeated administrations of BMAA, Spencer succeeded, after eight weeks, in inducing ‘a degenerative motor system disease’ associated with damage to the motor cells in the cerebral cortex and spinal cord.[70] He further observed that BMAA might have two distinct effects: given in high doses, it caused an ALS-like condition to develop rapidly; but smaller doses seemed to cause, after a considerably longer period, a parkinsonian condition – a double action reminiscent of the Guam disease.
These results seemed to refute the first criticism made in the 1960s of the cycad hypothesis – that there existed no animal model. Now Spencer, with a characteristic burst of energy, set about refuting the other, seemingly lethal criticism of the cycad hypothesis – that there were no cycads in the Kii Peninsula or Irian Jaya. Like Gajdusek had before him, he trekked into the jungles of Irian Jaya with his colleague Valerie Palmer – and they discovered that there were cycads here (though they seemed to be a different species from the Guam one). They found, moreover, that cycads were treated as veritable medicine cabinets by the local people, who used raw seeds (like the Chamorros) as poultices on open wounds. On the Kii peninsula, they went on to discover, cycads were also used medicinally, as tonics. With these two discoveries, in the lab and the field, the cycad hypothesis, discarded fifteen years earlier, was now revivified.
John could not contain his excitement at these new thoughts and findings – everything seemed to fit together perfectly. He would phone Spencer in New York, and the two would have excited conversations for hours, sometimes nightly, discussing clinical data, and bringing out more and more ‘coincidences’ of cycads and disease in the Marianas. With his colleague Tomasa Guzman, John now embarked on reexamining the whole question of cycad distribution and use in the Marianas. They observed that while lytico-bodig was common among the Chamorros on Guam and Rota, where cycads were plentiful, there was no lytico-bodig reported on the island of Saipan (at least none in the previous seventy years – it remained uncertain whether the Saipanese Chamorros had been prone to it before this).[71] But they pointed out that the cycad forests of Saipan had been cut down by the Japanese in 1914, to clear land for sugar cane, and that the use of fadang had ceased soon after this. And that on lytico-bodig – free Tinian, where there were forests of cycads, the Chamorros had never made use of them. They proposed that the family clusters of disease found on Guam, which did not follow any known genetic distribution, could be related to differences in the way each family prepared their fadang – some family recipes involved soaking the seeds overnight, some for three weeks; some would use seawater, some fresh; some would shorten the washing process so that the flour would have a stronger taste. Steele and Guzman ended their paper with some striking accounts of people who had developed lytico-bodig as long as twenty years after a single exposure to fadang.
But many researchers felt, after the first flush of enthusiasm, that the amounts of BMAA Spencer was feeding his monkeys were completely unphysiological – more than the most devoted fadang eater could consume in a lifetime. Indeed, Gajdusek calculated, to reproduce Spencer’s experiment in a human being, the subject would have to eat a ton and a half of unprocessed cycad seeds in twelve weeks. This in itself was not an annihilating criticism – experimental toxicology often uses massive doses of materials in its initial experiments in order to increase the chance of getting results within a reasonable time. But now John, knowing how meticulously the seeds were detoxified before the production of fadang, set about measuring the amount of BMAA the flour actually contained; he started sending samples out for analysis, and was surprised to find that many of these had very low levels of BMAA, and some almost none at all. With this he turned against the cycad hypothesis, which had so exercised him for more than three years – turned against it with the vehemence with which he had once espoused it.