This past weekend I listened to a really fascinating episode of the Radiolab podcast about stochasticity (which is a fancy word for randomness) and finding patterns.  One part of the episode explored the story of Ann Klinestiver, a teacher who was diagnosed with Parkinson’s disease and later become a gambling addict.  Evidently, it’s very common for people with Parkinson’s to develop a gambling addiction.

When I first heard this, it sounded preposterous.  Why would Parkinson’s disease have anything to do with gambling addiction?

Before this makes any sense, first we need to think about how dopamine works.

My understanding of the brain is pretty primitive – but according to the podcast, dopamine plays two key roles in the brain:

  • Role 1) “Pleasure” or reward indicator. Your brain releases dopamine when you’re doing something that feels good or is enjoyable.
  • Role 2) Movement and motor skills. Your brain uses dopamine as a key component of making your body move.

Parkinson’s is a disease where the part of your brain that uses dopamine to move (Role 2 above) starts to die.  That’s why Parkinson’s patients tend to have trouble with movement.

To treat Parkinson’s, patients take synthetic dopamine drugs to help with their movement (that’s where the shaking comes from – too much dopamine makes it hard to stop moving).

So – what does all this have to do with gambling addiction?

That’s where dopamine “Role 1” comes in.

It seems that our understanding of how dopamine works as a pleasure reward in the brain is actually somewhat recent.  Wolfram Shultz did a series of experiments in the 1990’s and early 2000’s that helped shed more light on the subject.

Schultz’s primary experiments focused on giving monkeys juice and watching the dopamine response in their brains.  He hooked monkeys up to a series of sensors, then went into the lab every day and give them a drink of juice.  At first, the monkeys would drink the juice and, in response to the juice, get a shot of dopamine from their brains.  Then over time, the monkeys would start to expect the juice and the dopamine response would hit earlier, for example, when the lab door opened.  Eventually the monkeys would get the dopamine response when they were first able to hear the footsteps of the researchers as they started walking down the hall outside the lab.

I thought this part was really fascinating.  Evidently our brains, at a primal level, are constantly looking for patterns.  Whenever we get a reward (something good happens), we search for all the moments leading up to that reward and try to link stimuli we received prior to the reward to the reward itself.  If the pattern repeats, our brain starts giving us shots of dopamine when we do the things that historically have led to the reward.

We’re looking for patterns all the time.

Now, here’s why slot machines and other gambling apparatus are so sinister.  The machines are full of stimuli for our brains to latch onto.  Bells, sirens, ringing, lights, spinning things, etc.  Then when we get the reward (when we win some money), we look back and see all of the things that the machine did, and our brains start to shoot out dopamine when we see the bells and lights.

The problem is – slot machines are completely random.  There is no pattern.  So our brains are constantly correcting and readjusting to new signals to try to figure out what led to us winning money.  Gambling addicts are, in effect, endlessly trying to find a pattern where there is none.

So what’s the connection to Parkinson’s disease?

Well, for the reasons mentioned above, slot machines can be hard to resist for people with normal brains. When you’re on Parkinson’s medication, the dopamine you loaded up in your brain to help you move (Role 2) also greatly enhances the reward signal you get (Role 1) and, dramatically increases the likelihood you will become addicted to gambling.  Said differently, pump your brain full of synthetic dopamine and you may find the sirens and bells of a slot machine to be completely irresistible.

Kind of makes me think about my own dopamine responses – what I find enjoyable and what work I find easy or compelling to do.  All around, I thought this was an interesting lesson, I hope you think so too.

Dopamine and How our Brains Look for Patterns
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