Overcoming an Overvalued Idea Using Experimental Methods

A 68-year-old scientist, married with three children, presented to the emergency department with shortness of breath, bradycardia but without chest pain. He attributed his decreased heart rate (HR) to accidental inhalation of carbon monoxide (CO) ‘fumes’ from a car that had entered his unit complex.

On examination: HR 30/min, irregular. Troponin < 0.1; ECG demonstrated complete heart block (CHB)

The cardiology department recommended the insertion of a permanent pacemaker (PPM), however he refused. He reported that he had first experienced a slowed heart rate while jogging along a ‘CO polluted’ highway three years earlier and had subsequently reached the conclusion that CO was the cause of multiple subsequent episodes of bradycardia. He believed that a decrease in HR after CO exposure was an ‘inbuilt protective mechanism’ to prevent further uptake of CO and further cardiac damage. He reasoned that a PPM would reduce this protection and might cause the heart to be further damaged. As an alternative to a PPM the patient asked for treatment with ‘normobaric oxygen’.

The patient reported that he had undertaken extensive measures to reduce CO exposure including sealing door frames; duct tape around car window edges; wearing a facemask; driving to work early to avoid pollution; wanting to move to a coastal location; and purchase of home O₂. He had also found literature on the Internet affirming his beliefs. In hospital he slept on the floor to avoid CO and could smell the ‘fumes’.

Past psychiatric history included a previous episode of depression treated with amitriptyline. There was no significant medical, drug or alcohol history, regular medications or family history of mental illness. Premorbid personality traits included attention to detail.

On mental state examination he was well groomed, engaging and spoke articulately without evidence of a disorder of thought form. His mood was euthymic, affect reactive and appropriate.

We considered that his ideas about CO were probably overvalued rather than delusional because he was prepared to entertain other explanations for his CHB other than CO. His beliefs were based on inductive reasoning, and his anxious personality style, rather than a morbid psychological process such as hallucinations or thought disorder.

Differential diagnoses of delusional disorder, paranoid personality disorder and late onset schizophrenia were considered.

His capacity to make a decision about treatment was considered to be impaired by his beliefs in the cardiotoxic properties of atmospheric CO and a dialogue was commenced with the aim of maximizing his capacity by the provision of more information. To this end the hospital's hyperbaric medicine unit was asked to discuss his ideas about normobaric O₂ therapy. As a result an unblinded single subject cross-over trial of normobaric 100% O₂ via a non-rebreather mask was proposed. He agreed prospectively that if his heart was not in sinus rhythm after 2 h, then he would consent to a PPM. A PPM was inserted on the ninth day of admission. Afterwards, he remained preoccupied with CO poisoning, though to a lesser extent and referred to it as his ‘hypothesis’.

Distinguishing between an overvalued idea and delusion is a core skill for psychiatrists that can spare non-deluded patients unhelpful antipsychotic medication. Jaspers described a delusion as an abnormal belief that is false, held with certainty and is incorrigible [1]. Given this man's belief could be challenged, it is more consistent with what Wernicke described as an ‘overvalued idea’, which is neither delusional nor obsessional, but preoccupies the person to the extent that it dominates their life [2,3].

Maximizing the decisional capacity is an essential skill for all doctors, and in some situations can be a complex and lengthy process. Many patients need more education, in this case the patient/scientist was ultimately convinced by an experiment.