summary
An 81-year-old woman was diagnosed with chronic carbon monoxide poisoning. Her symptoms closely resembled those of someone with depression, although some of her symptoms were atypical. Because carbon monoxide is a colourless, odourless gas, the cause of her condition remained unclear for several weeks. If psychiatrists are better informed about the affective and neuropsychological symptoms that frequently accompany carbon monoxide poisoning, they should be able to recognise the symptoms sooner. This in turn should lead to a better outcome for the patient.