Jessica George ’24

Psychosis in Parkinson’s Disease (PD) is characterized by visual hallucinations (VHs). These VHs have a significant impact on patient’s lives and serve as a reliable predictor for future nursing home institutionalization. Several disorders such as Charles Bonnet syndrome and temporal lobe epilepsy have similar features to those of PD VHs. In the aforementioned disorders, EEG analysis revealed epileptiform discharges, which led researchers to wonder whether similar abnormalities existed in the EEGs of PD patients with VHs.

Dr. Adam Fry from the Icahn School of Medicine and colleagues observed and studied medical records of 300 PD patients. Among  the patients with at least 20 minutes of EEG readings, those who had pre- existing epilepsy and seizure disorders as well as those  taking anti-epileptic drugs were excluded. The remaining 44 patient records were then separated into patients with VHs and patients without. Afterwards, Dr. Fry and his team analyzed the EEGs of each patient. Analysis revealed that 5 out of the 13 (38.5%) PD patients with VHs presented with localized epileptiform discharges in the temporal lobe (two left, two right, and one bilaterally). Additionally, all of the 31 PD patients without VHs displayed no epileptiform discharges, illustrating that these abnormalities are unique to PD presenting with VHs. 

These findings can help enhance understanding of the neurobiologic underpinnings of VHs. Further, as these epileptic discharges were all localized to the temporal lobe, researchers can gain better insight on which areas of the brain should be targeted for therapies. It has been suggested that restricting the use of antiparkinsonian medications that are often used for epilepsy should be emphasized as they have been shown to reduce the potentiation of VHs. However, VHs continue to persist among drug-naive patients. Finding a reliable and effective therapy for PD VHs can also lead to finding effective therapies for similar disorders such as Charles Bonnet syndrome and temporal lobe epilepsy. Ultimately, therapies targeting reducing VHs may lead to decreasing nursing home institutionalization rates in PD patients. Though this observational study opens doors to understanding the neurobiology behind PD VHs, a greater participant cohort with longer EEG readings are needed in prospective studies  to validate the findings in this prospective study. 

Works Cited:

[1] A. Fry, et al., Parkinson’s disease with visual hallucinations is associated with epileptiform activity on EEG. Front Neurol., (2022). doi: 10.3389/fneur.2021.788632.

[2] Image retrieved from: https://www.flickr.com/photos/didmyself/16537232895