The present study evaluated the dementia risk after carbon monoxide poisoning (CO poisoning). … This study suggests that CO poisoning may have association with the risk of developing dementia, which is significant for severe cases.

The present study evaluated the dementia risk after carbon monoxide poisoning (CO poisoning).

Using the National Health Insurance Research Database of Taiwan, a total of 9041 adults newly diagnosed with CO poisoning from 2000 to 2011 were identified as the CO poisoning cohort. Four-fold (N = 36,160) of non-CO poisoning insured people were randomly selected as controls, frequency-matched by age, sex, and hospitalization year. Incidence and hazard ratio (HR) of dementia were measured by the end 2011.

The dementia incidence was 1.6-fold higher in the CO exposed cohort than in the non-exposed cohort (15.2 vs 9.76 per 10,000 person-years; n = 62 vs 174) with an adjusted HR of 1.50 (95% CI = 1.11–2.04). The sex- and age-specific hazards were higher in male patients (adjusted HR = 1.74, 95% CI = 1.20–2.54), and those aged <=49 years (adjusted HR = 2.62, 95% CI = 1.38–4.99). CO exposed patients with 7-day or longer hospital stay had an adjusted HR of 2.18 (95% CI = 1.42, 3.36). The CO poisoning patients on hyperbaric oxygen (HBO2) therapy had an adjusted HR of 1.80 (95% CI = 0.96–3.37).

This study suggests that carbon monoxide poisoning may have association with the risk of developing dementia, which is significant for severe cases. The effectiveness of HBO2 therapy remains unclear in preventing dementia. Patients with CO poisoning are more prevalent with depression.


The Global Burden of Disease Study has ranked dementia the 5th common chronic disease.1 The Institute for Health Metrics and Evaluation (IHME) has estimated that there was a 112.8% increase in the disability-adjusted life-year cost for dementia in 2010 compared that in 1990. It was anticipated that the cost would increase further for more than 80% by 2030.1 The Alzheimer Disease International (ADI) Report has also estimated that approximately 44.4 million people were affected by dementia in 2010, and this number would increase to 75.6 million by 2030 and 135.5 million by 2050. In 2010, the Global total social costs for dementia were estimated to be US $ 604 billion, corresponding to 1.0% of the global GDP.24Dementia is more important than Alzheimer disease alone in causing a huge economic burden.57Dementia is the brain disease characterized by impaired memory and loss of thinking and reasoning, which severely affect the patient’s daily functioning.8

The risk of developing dementia has been associated with several conditions, including alcohol abuse (alcohol-related dementia), chronic traumatic encephalopathy, drug side effects, depression, and other central nervous system disorders.915 Establishing a link between associated risk factors and dementia may provide appropriate means of treatment and counseling, thereby reducing the risk of dementia and costs of treatment.

Carbon monoxide (CO) poisoning is a common and important cause of death among populations, including populations in the United States, and England and Wales.16 Approximately 15,000 unintentional nonfire related episodes of CO poisoning have been reported annually in England and Wales, leading to 50,000 emergency department visits and 500 deaths.17 The memory difficulty and confusion are initial neurological symptoms of acute CO poisoning in addition to headache, weakness, dizziness, nausea, and vomiting.15 Furthermore, unconsciousness, respiratory arrest, and even death could develop for the CO poisoning victims.17 Previous studies have reported that up to 30% of patients result in the sequelae of neurologic complications after the poisoning.18,19 Intellectual function impairments, short-term memory loss, dementia, amnesia, psychosis, irritability, dysfunctional gait, speech disorders, Parkinson disease-like syndrome, cortical blindness, and depression are among the poisoning sequelae.20,21 Victims of CO poisoning may suffer from brain hypoxia, inflammation, and subsequent injuries.22 Patients with ischemia-reperfusion injury exposing to high oxygen may aggravate the oxidative damage after recovery from CO poisoning.23,24 Encephalopathy and other neuropsychiatric disorders are other sequelae in victims. It remains unclear whether such abnormalities increase the risk of dementia.2528 In an earlier Japanese study, Mimura et al28 found considerable sequelae in CO poisoning patients after follow-up for 33 years. No large-scale long-term follow-up study has ever evaluated this relationship. The present study was conducted to evaluate whether patients with CO poisoning are at an elevated risk of developing dementia.