Finding agency amid the threat of Parkinson’s disease psychosis

There’s a particular kind of fear that creeps in when living with Parkinson’s disease. It’s not the shaking or the stiffness that haunts me the most; it’s the quiet dread that my own mind might one day turn against me. Not in some dramatic, movie-style way, but in the subtle shifting of perception, when I’m no longer quite sure what is real. When the boundary between what’s out there and what’s inside begins to blur. I’m talking about the psychosis — hallucinations, delusions — that sometimes comes with Parkinson’s.

If you’ve ever experienced even a flicker of it, or known someone who has, you understand why it feels so destabilizing. It’s not just about seeing things that aren’t there. It’s about the horrifying possibility that the very mechanism you rely on to know what is real — your perception — might become unreliable. That thought alone can be more frightening than the symptoms of Parkinson’s themselves.

But I’ve been trying hard to understand this from a different angle. Not to dismiss the fear, but to frame it in a way that feels less like unraveling and more like unveiling. And I keep coming back to the work of two authors and neuroscientists who offer models of the brain that, oddly enough, help me find some peace in the uncertainty: Anil Seth and David Eagleman.

A different way to think about psychosis

Let’s start with Seth, who proposes that all perception is a controlled hallucination. That idea may seem jarring, especially if you’re clinging to a sense of objective reality. But Seth doesn’t mean that we’re all delusional; rather, he argues that our brain is constantly making predictions about the world based on sensory input, and those predictions are what we perceive. In essence, we’re hallucinating all the time — it’s just that when our hallucinations are accurate, we call it reality.

For a neurotypical brain, these predictions are tightly constrained by incoming data. But with Parkinson’s, those constraints begin to loosen. The dopaminergic system — which helps modulate precision, expectation, and reward — is disrupted. That means the brain’s guesses about what’s happening in the world become less reliable, less anchored to what’s really out there. A shadow in the corner becomes a figure. A flicker of light turns into a face.

It’s terrifying, but it’s not madness in the way we’ve traditionally thought about it. It’s the same machinery everyone uses to perceive the world, just destabilized. It’s a controlled hallucination losing control.

Now enter Eagleman, who describes the brain not as a unified command center, but as a team of rivals — a collection of competing neural factions, each with their own priorities, fighting it out to guide behavior. It’s an elegant metaphor, borrowed from Abraham Lincoln’s cabinet, that captures the messy, dynamic, often contradictory nature of consciousness. We are not one voice, but many, and our experience of the world is the result of negotiation, not consensus.

This framework helps explain why psychosis doesn’t necessarily feel like a total loss of reality: because some part of you still knows. Some part of the “team” is waving a flag, saying, “This isn’t right,” even as another part insists on the hallucination. The fear comes when that balance starts to tip — when the more rational voice is drowned out, when your internal rivals no longer play fair.

And so I wonder: What part of my brain is meant to be the arbiter, the stabilizer, the one that says, “No, that’s not real”? And what happens if that part — whether it’s the prefrontal cortex, the thalamus, or some orchestrating network — begins to weaken or fade?

It’s a chilling question, but it also leads me to hope. Because if the brain is a system of competing voices, maybe we can learn to train the ones we trust. Maybe therapy, medication, and sensory interventions aren’t just about suppressing symptoms; maybe they’re about strengthening the dominant players on the team, the ones that can still anchor us to reality.

This is not to minimize the suffering. Hallucinations can be deeply disturbing, especially when they blur the line between perception and paranoia. But maybe the model we need is not one of disease vs. health, but one of harmony vs. dissonance. A mind that’s improvising, sometimes off-key, sometimes hauntingly beautiful.

For those of us with Parkinson’s, the possibility of psychosis looms like a storm cloud. But understanding the brain not as broken but as a prediction machine with internal rivalries gives me a sense of agency. If I can learn to listen closely, to notice which voices are speaking, to adjust the inputs, maybe I can help shape the hallucination toward coherence. Toward something I can live with.

In the end, maybe we’re all just trying to hold the line between chaos and clarity. And maybe, with the right model — a team of rivals guided by careful hallucination — we can still find our way through the fog.

Even when the world looks strange. Even when our own minds feel unfamiliar.

Note: Parkinson’s News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Parkinson’s News Today or its parent company, Bionews, and are intended to spark discussion about issues pertaining to Parkinson’s disease.