Cognitive ability and impairment related to formaldehyde

Abstract

Recent studies have shown that dysmetabolism of formaldehyde may be one of the various patho-mechanisms involved in the onset and progression of age-related cognitive impairment including Alzheimer's disease (AD) and vascular dementia (VD). High endogenous formaldehyde levels could be a risk factor for cognitive impairment in the elderly population. Using a double-blind experiment, the correlation between endogenous (urine) formaldehyde and general cognitive abilities was estimated in a community-based elderly population (n = 604). Yu and her colleagues measured the general cognitive abilities of aged people using the Montreal Cognitive Assessment (MoCA) and then correlated them to concentrations of urine formaldehyde. Urine formaldehyde levels were inversely correlated with the MoCA scores of elderly participants. The concentration varied with demographic features: higher odds of a high formaldehyde level occurred among the less educated elderly population. Educational levels are strikingly correlated with the concentration of endogenous formaldehyde for the elderly living in local communities in Beijing. The epidemiological investigation showed that the average concentration of urine formaldehyde of the elderly increases with aging (>75 years old). In clinical study, the concentration of urine formaldehyde of AD patients is inversely correlated with their Mini-Mental State Examination (MMSE) scores. The old patients with the postoperative cognitive dysfunction (POCD) suffered from high levels of endogenous formaldehyde after their surgeries, but those without POCD did not. Monkeys fed with low concentration of methanol suffered from working memory loss. Levels of hippocampal formaldehyde from the patient autopsy are significantly higher than those of age-matched normal controls. Therefore, endogenous formaldehyde could be developed as a noninvasive marker for detection and monitoring of age-related cognitive impairment for both AD and VD, which could be identified with patients' history and further examinations.