Formaldehyde as a trigger for protein aggregation and potential target for mitigation of age-related, progressive cognitive impairment.

Recently, formaldehyde (FA), existing in a number of different cells including neural cells, was found to affect age-related cognitive impairment. Oral administration of methanol (the metabolic precursor of FA) triggers formation of senile plaques (SPs) and Tau hyperphosphorylation in the brains of monkeys with memory decline. Intraperitoneal injection of FA leads to hyperphosphorylation of Tau in wild-type mouse brains and N2a cells through activation of glycogen synthase kinase-3ß (GSK-3ß). Furthermore, formaldehyde at low concentrations can directly induce Tau aggregation and amyloid ß (Aß) peptide deposits in vitro. Formaldehyde-induced Tau aggregation is implicated in cytotoxicity and neural cell apoptosis. Clarifying how FA triggers Aß deposits and Tau hyperphosphorlyation will not only improve our understanding of the molecular and cellular mechanisms of age-related cognitive impairment but will also contribute to the ongoing investigation of alternate targets for new drugs. Here, we review the role of FA, particularly that of endogenous origin, in protein aggregation and as a potential drug intervention in the development of agerelated cognitive impairment.

Dietary methanol and autism.

The authors sought to establish whether maternal dietary methanol during pregnancy was a factor in the etiology of autism spectrum disorders. A seven item questionnaire was given to women who had given birth to at least one child after 1984. The subjects were solicited from a large primary care practice and several internet sites and separated into two groups - mothers who had given birth to a child with autism and those who had not. Average weekly methanol consumption was calculated based on questionnaire responses. 550 questionnaires were completed by women who gave birth to a non-autistic child. On average these women consumed 66.71mg. of methanol weekly. 161 questionnaires were completed by women who had given birth to an autistic child. The average estimated weekly methanol consumption for this group was 142.31mg. Based on the results of the Wilcoxon rank sum-test, we see a significant difference between the reported methanol consumption rates of the two groups. This study suggests that women who have given birth to an autistic child are likely to have had higher intake of dietary sources of methanol than women who have not. Further investigation of a possible link of dietary methanol to autism is clearly warranted.

Methanol: a chemical Trojan horse as the root of the inscrutable U.

Until 200 years ago, methanol was an extremely rare component of the human diet and is still rarely consumed in contemporary hunter and gatherer cultures. With the invention of canning in the 1800s, canned and bottled fruits and vegetables, whose methanol content greatly exceeds that of their fresh counterparts, became far more prevalent. The recent dietary introduction of aspartame, an artificial sweetener 11% methanol by weight, has also greatly increased methanol consumption. Moreover, methanol is a major component of cigarette smoke, known to be a causative agent of many diseases of civilization (DOC). Conversion to formaldehyde in organs other than the liver is the principal means by which methanol may cause disease. The known sites of class I alcohol dehydrogenase (ADH I), the only human enzyme capable of metabolizing methanol to formaldehyde, correspond to the sites of origin for many DOC. Variability in sensitivity to exogenous methanol consumption may be accounted for in part by the presence of aldehyde dehydrogenase sufficient to reduce the toxic effect of formaldehyde production in tissue through its conversion to the much less toxic formic acid. The consumption of small amounts of ethanol, which acts as a competitive inhibitor of methanol's conversion to formaldehyde by ADH I, may afford some individuals protection from DOC.