Glenn started new treatment for Parkinson's. Then came the obsessive sexual thoughts

What do extreme sports, doomscrolling, addiction, Parkinson's disease, and ADHD all have in common? Dopamine. This crucial neurotransmitter helps facilitate reward, motivation, memory and movement within the body, but are its effects always beneficial? Watch Insight episode Chasing Dopamine Tuesday 11 August 8.30pm on SBS or SBS On Demand.

When Glenn Peterson started on a higher dosage of medication to treat his Parkinson's disease symptoms, he didn't expect the consequences it would have.

"I developed some bad habits and some obsessions," he told Insight.

"I'd see a horse race, and I'd want the thrill of it winning, and betting on it. I had constant thoughts of sex as well, which never entered my mind prior to that. I couldn't get rid of it."

The 73-year-old was diagnosed with Parkinson’s disease eight years ago. He was taking a dopamine precursor medication — a drug the body converts to dopamine when it reaches the brain — to treat his symptoms. He was later prescribed a dopamine agonist as well to make treatment more effective.

While the brain converts dopamine precursors directly into dopamine, dopamine-agonist medications mimic dopamine by activating dopamine receptors in the brain.

When combined, these drugs help treat the motor symptoms of Parkinson's, a progressive brain disorder that damages dopamine-producing neurons, but research shows agonist drugs can cause the development of compulsive and addictive behaviours.

Glenn says when the dopamine-agonist medication was increased, he developed these behaviours.

Glenn's wife, Robyn, also noticed the change when he started getting up in the middle of the night for hours at a time.

"I started asking what he was doing when he was awake at night," Robyn said.

"And it started to come out that he was playing games ... or he'd gamble on the poker machines on his iPad through the night or go onto porn sites."

Glenn couldn’t understand why his mind seemed to turn against him. But when he revealed the extent of his newly developed compulsive behaviours to Robyn, she remembered the doctors had warned them that taking dopamine-agonist medication could bring on these side-effects.

They spoke to Glenn's neurologist and decreased his dose, which put an end to the compulsive behaviours.

The link with dopamine and Parkinson's disease

Dopamine is a neurotransmitter in the brain that is involved in several of the body's functions, including movement — and contributes to our motivation and reward systems.

As it reinforces behaviours linked with reward or survival-based outcomes (such as eating food), it contributes to habit development — but is also why it plays a role in addiction.

Dopamine is not itself addictive, but the associated substances, behaviours or activities that cause the brain to release dopamine can be.

Karly Turner is a behavioural neuroscientist at the University of New South Wales, and says when someone has Parkinson’s, neurons that produce dopamine are degraded, which causes movement deficits.

"People with Parkinson's are often able to move in a direction, but then when they go to change direction or change their action, they'll get a bit stuck — and that's because of the lack of these dopamine neurons," Turner told Insight.

She says that research suggests that dopamine agonists, which act like dopamine in the brain, cause about 15 to 20 per cent of people with Parkinson's to experience impulse control disorders.

"Different medications act in different ways ... but when we take an oral medication, it is going to have that effect on the whole brain — not just the circuit that we're going to try to target or the circuit that we're having problems with," she said.

"It is also important to talk to your doctor if you do experience any symptoms so that they can refine their approach."

In addition to movement, Turner notes that dopamine often affects risk-taking.

"We see some people being more sensation seekers," she said.

"They're driven by this chase of reward and excitement and novelty, which are more likely to take risks, in these kinds of circumstances [such as skydiving]."

Seeking out risk

Gomeroi man Marley Nolan-Duncan says he chased dopamine through risky activities such as jumping off bridges into water and riding motorbikes when growing up in regional NSW, but they progressed into illegal ones.

"Not proud of it, about [the] crime side of things: stealing cars, breaking into houses," the 43-year-old says.

"It was more that rush. I wasn't a career criminal at all ... but that rush — not the crime."

But as he matured, "sensation seeker" Marley found another risky activity to seek dopamine through in his early 20s: skydiving, which he has kept up for the past 15 years.

"[On my first jump], I was looking down at the ground just going, 'Holy crap. I'm about to jump out of a plane.'

"But a part of me was like, 'I can't wait' ... I was buzzing off that rush [when I landed] and I was like, 'Where do I learn?'"

Five years ago, however, he broke his leg on a jump and was out of action for five months, which negatively impacted his mental health.

"I was pretty much bedbound [and] had a wheelchair," he said.

He says he briefly turned to alcohol and abused painkillers to numb the absence of dopamine he got from skydiving. This affected his marriage with his wife Carolin, and he moved out for a period of time.

Eventually, he overcame the period of medication and alcohol abuse.

"I said to myself, 'I never want to go back there again,'" he said.

"But being there, I've learned a lot about myself and about those situations and how to handle them a bit better and try and stay out of that space."

He is back to skydiving but now also seeks dopamine in slower ways, such as playing with his children.

ADHD and dopamine

Zoe Mac has also been a dopamine chaser for most of her life — seeking the "quick fix" from sugary snacks, online games, op-shopping and doomscrolling.

The 52-year-old from the Gold Coast says receiving an ADHD diagnosis in her 40s made her realise that might be a prominent factor in her dopamine seeking.

"I started learning more about [ADHD] — digging even deeper on the dopamine journey," she says.

"From there I was able to be so much kinder to myself because I wasn't flawed. My brain has a different makeup."

Anastasia Hronis, a clinical psychologist at the University of Technology Sydney, says that ADHD was initially thought to be related to an underproduction or deficit in dopamine, but research now shows it is more complicated than that.

"[It is] actually a dysregulation in the way that dopamine is activated, particularly in relation to the prefrontal cortex, so the part of our brain that helps us make decisions and plan — also the reward centres," she said.

"And a lot of the people, at least that I have seen clinically who present with an addiction, may often actually have undiagnosed ADHD, and they throughout their life have found ways to kind of regulate themselves when they have a brain that is in some ways dysregulated."

The psychologist said that although dopamine is neither good nor bad, the way we activate dopamine can make a difference.

"If we are putting effort into the task that we are doing, and we're having that dopamine reward and activation at the end of that, that is a healthier way — compared to things that are very quick and easy, and don't require any effort."

She says that because boredom may feel "uncomfortable", we can be "particularly vulnerable to perhaps being pulled to some of those more dopamine-driven behaviours" such as reaching for sugary treats, binge-watching television or scrolling on the phone.

Zoe now has a healthier relationship with craving and has done two 30-day "dopamine detoxes" when she avoided "anything that could hook your attention" — including sugary snacks, online shopping and online games.

She said she was "deathly bored" in the first week and that it highlighted how strong her cravings for her phone had been.

"My hands were almost like, 'Please, pick up the phone and play a game," she said.

"It took so much willpower."

'The perfect storm'

Turner says that scrolling is "the perfect storm for having a dopamine release" because you don't know what's coming next, but the "algorithm is making sure that the stuff you're seeing is the stuff you like".

"Things that have previously been rewarded ... things that have triggered dopamine for you in the past are the things that are probably popping up in your scroll in an unpredictable manner."

Hroni says there has been "a lot of sensationalisation" around dopamine detoxes on social media in recent years — some heralding 24-hour fixes — but that psychologists would typically recommend around one month as a period of abstinence from something.

"That said, if someone has somewhat more of an addictive tendency to something that is much more intense, it can sometimes take up to three months or more for the brain to kind of recalibrate and come back to a level of homeostasis."

The financial cost of dopamine

Like Zoe, Steph Thompson, 32, used to also seek dopamine hits through scrolling and online shopping. To curb these cravings and to save money, she and her husband did a no-buy challenge a few years ago.

It involved avoiding unnecessary purchases whenever possible for two years.

"It's a lot of little things, and it really ended up being a lot of dopamine chasing," the Melbourne content creator says.

"If you had a bad day, let's get takeout. If you're wanting to feel better in some kind of way, there was always a way that money could fill that void. And it just became a pattern of little things over time, much like social media usage."

Steph says that watching her spending closely made her analyse her everyday habits, and the role dopamine played in them.

"I kind of started to realise that what was driving me to spend was also driving me to scroll."

'Changed completely'

Glenn believes the compulsive behaviours he was experiencing might have continued or become worse had it not been for his wife.

"It really was an eye-opener of what this additional dose could do to a person," Robyn said.

"Changed him completely."

Watch your favourite Insight episodes around the clock on SBS On Demand's dedicated Insight channel.

For the latest from SBS News, download our app and subscribe to our newsletter.