Let's talk about Apathy and Parkinson's

What is apathy?
Apathy is defined as, “a loss of motivation leading to a reduction in goal-directed behaviors” (Béreau, 2023)

Apathy, which often shows up in Parkinson's disease, isn’t just “feeling lazy” or even necessarily feeling sad. Apathy occurs when the brain’s motivation system gets dialed down. This causes a desire to act without internal push to do so. This is heavily tied to the brain’s dopamine pathways or "reward circuit.”

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Dopamine is largely responsible for anticipation and drive, so when these signals are disrupted, everyday tasks may no longer feel worth initiating. Those with apathy can still fully enjoy an activity once they are doing it. The barrier is starting - not the activity itself.

The Brain’s Reward Circuit
The Mesolimbic Pathway is often described as the brain’s “motivation highway,” but it’s less about pleasure and more about deciding what’s worth your time and energy. The brain’s reward circuitry is one of the most important systems behind motivation, and it’s an area that often starts to go off track in Parkinson's disease.

At the center of this system is dopamine – the brain’s chemical messenger responsible for regulating movement, emotion, and reward. While motivation may seem solely dependent on enjoying an activity, it’s also affected by your brain determining if the activity will be rewarding enough. For example, you may not enjoy your job, but making money is a huge reward, so it is worth the effort for most people. Dopamine is about the reward, not just the enjoyment.

 highWhat changes in Parkinson’s
When PD causes dopamine-producing neurons to degenerate, the reward system can be heavily affected. Dopamine signals weaken and the “this is worth doing” signal becomes faint. This leads to “effort discounting”: when effort starts to feel disproportionately high compared

to reward (McGuigan, 2019). When this happens, initiating a task can feel impossible – even if if the individual wants to act. Simple activities such as calling a friend or engaging in a hobby stop feeling as though they’re worth the effort.

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