The Meds That Impair Decision-Making

Impairment to cognitive function is often comorbid with Parkinson’s disease. That is to say: it’s not a symptom of Parkinson’s, but it often occurs in the same people. This may seem natural: after all, both are strongly associated with aging.

However, recent (last month, at time of writing) research has brought to light a very specific way in which medication for Parkinson’s may impair the ability to make sound decisions.

Obviously, this is a big deal, because it can affect healthcare decisions, financial decisions, and more—greatly impacting quality of life.

See also: Age-related differences in financial decision-making and social influence

(in which older people were found more likely to be influenced by the impulsive financial preferences of others than their younger counterparts, when other factors are controlled for)

As for how this pans out when it comes to Parkinson’s meds…

Pramipexole (PPX)

This drug can, due to an overlap in molecular shape, mimic dopamine in the brains of people who don’t have enough—such as those with Parkinson’s disease. This (as you might expect) helps alleviate Parkinson’s symptoms.

However, researchers found that mice treated with PPX and given a touch-screen based gambling game picked the high-risk, high reward option much more often. In the hopes of winning strawberry milkshake (the reward), they got themselves subjected to a lot of blindingly-bright flashing lights (the risk, to which untreated mice were much more averse, as this is very stressful for a mouse).

You may be wondering: did the mice have Parkinson’s?

The answer: kind of; they had been subjected to injections with 6-hydroxydopamine, which damages dopamine-producing neurons similarly to Parkinson’s.

This result was somewhat surprising, because one would expect that a mouse whose depleted dopamine was being mimicked by a stand-in (thus, doing much of the job of dopamine) would be less swayed by the allure of gambling (a high-dopamine activity), since gambling is typically most attractive to those who are desperate to find a crumb of dopamine somewhere.

They did find out why this happened, by the way, the PPX hyperactivated the external globus pallidus (also called GPe, and notwithstanding the name, this is located deep inside the brain). Chemically inhibiting this area of the brain reduced the risk-taking activity of the mice.

This has important implications for Parkinson’s patients, because:

• on an individual level, it means this is a side effect of PPX to be aware of
• on a research-and-development level, it means drugs need to be developed that specifically target the GPe, to avoid/mitigate this side effect.

You can read the study in full here:

Pramipexole Hyperactivates the External Globus Pallidus and Impairs Decision-Making in a Mouse Model of Parkinson’s Disease

Don’t want to get Parkinson’s in the first place?

While nothing is a magic bullet, there are things that can greatly increase or decrease Parkinson’s risk. Here’s a big one, as found recently (last week, at the time of writing):

Air Pollution and Parkinson’s Disease in a Population-Based Study

Also: knowing about its onset sooner rather than later is scary, but beneficial. So, with that in mind…

Recognize The Early Symptoms Of Parkinson’s Disease

Finally, because Parkinson’s disease is theorized to be caused by a dysfunction of alpha-synuclein clearance (much like the dysfunction of beta-amyloid clearance, in the case of Alzheimer’s disease), this means that having a healthy glymphatic system (glial cells doing the same clean-up job as the lymphatic system, but in the brain) is critical:

How To Clean Your Brain (Glymphatic Health Primer)

Take care!