The Neurologist has a fascinating case report of a women with Parkinson’s disease who experienced a fluctuating belief that she didn’t exist.
Cotard’s delusion is usually described as the ‘belief that you’re dead’ although Jules Cotard, for whom the delusion is named, defined it as a délire des négations – the delusion of negation, or nihilism, as it’s usually translated.
In fact, in his original case report, Cotard’s patient didn’t believe they were dead but that they had “no brain, nerves, chest, or entrails, and was just skin and bone”.
This new case report in The Neurologist describes a patient with Parkinson’s disease who experiences something similar with the delusion appearing as their Parkinson’s medication began to wear off.
In December 2010, she went to follow-up visit accompanied by her caregivers and they reported that, in the last 2 months, the patient has developed a sudden onset of nihilistic delusion, mainly during the “wearing-off” condition and associated with end of dose dyskinesias and akathisia. The patient repeatedly complained of having lost both of her eyes, mouth, nose, and ears. Often during these events, she insisted to have a mirror to see herself. She expressed the false belief that she did not have the whole body and that nothing existed, including herself, without any insight. This nihilistic delusion, compatible with the diagnosis of Cotard syndrome, clearly improved with the administration of the following dose of levodopa and the associated amelioration of motor symptoms.
This is interesting because the Parkinson’s medication – levodopa – is a precursor to dopamine and is used to increase dopamine levels in the brain.
Increased dopamine levels in mid-brain areas are considered to be a key causal factor in generating the delusions and hallucinations of psychosis, but in this case delusions reliably appeared as dopamine levels were likely to have been dropping due to the medication wearing off.
Although this is a single case study, the effect was reliable when repeated, but it doesn’t mean that this would happen with everybody in the same situation.
But what it really shows is that the neurobiology of psychosis is not a simple ‘chemical imbalance’ but, in part, a complex dysregulation that can effect individuals differently due to the inherent interconnectedness of neural systems.
Link to PubMed entry for case report.