Cognitive decline and hallucinations are common features of late-stage Parkinson’s disease. However, during the early stages of the disease, many people experience minor hallucinations – such as sensing an unseen person nearby or seeing a shadow pass in one’s peripheral vision – potentially indicating future cognitive deline. A recent study found that people with Parkinson’s disease who experienced minor hallucinations exhibited altered brain wave activity.

Researchers interviewed 75 people with Parkinson’s disease to determine whether they experienced minor hallucinations. Then, using electroencephalography (EEG), they analyzed their brain wave activity. They repeated the EEG five years later.

They found that those who experienced minor hallucinations – roughly half of the participants – had altered theta oscillations in the frontal part of their brains. These alterations were associated with poorer cognitive abilities in the frontal and subcortical regions of the brain. At the five-year follow-up, they found that participants with more frontal theta alterations during the initial assessment had a greater decline in their frontal and subcortical cognitive functions.

Theta oscillations are rhythmic, electrical brain waves occurring at approximately four to eight cycles per second, typically observed during deep relaxation, daydreaming, and certain stages of sleep. Theta waves play a crucial role in various cognitive processes, such as memory formation, learning, and spatial navigation. They enable communication and synchronization between brain regions, facilitating efficient information processing and integration.

These findings suggest that changes in frontal theta oscillations could be an early marker for cognitive decline in people with Parkinson’s disease. Exercise may slow the progression of Parkinson’s disease. Learn more in this episode featuring Parkinson’s expert Dr. Giselle Petzinger.

• Read study abstract.