Since June of 2005, the National Institute of Neurological Disorders and Stroke (NINDS) has been conducting a study to find out how to better treat depression in Parkinson's disease. If you do any reading about Parkinson's disease, you know that around half of the people living with Parkinson's disease also confront depression at some time. There are a number of medications that treat depression, and to be approved they had to go through clinical trials, just like any other medication. However, there is a lack of information coming from research to identify treatments that are ideal for the population with Parkinson's disease.
The ongoing study from the NINDS attempts to gauge the effectiveness of two popular medications for depression in the Parkinson's disease population. Venlafaxine (brand name Effexor) is a medication that increases the amount of serotonin available in the brain; and, at higher doses also increase the amount of norepinephrine available in the brain. The class of medication that augments both of these brain chemicals is the serotonin and norepinephrine reuptake inhibitors, or SNRIs. Venlafaxine is popular with physicians because it has shown effectiveness in helping patients who suffer from depression. However, it has also demonstrated the ability to treat anxiety. The two often go hand in hand.
Paroxetine (brand name Paxil) is a depression medication that works in a way quite similar to Prozac and Zoloft. It works by increasing the amount of serotonin available in the brain. Physicians often refer to medications with this type of action as selective serotonin reuptake inhibitors, or SSRIs.
The most popular theory about the cause of depression is that it is related to an imbalance in dopamine, serotonin and norepinepherine, the neurotransmitter chemicals in the brain. Sure there are events in life that may contribute to this imbalance; and, some people probably inherit genes that may influence the imbalance. Well, if Parkinson's disease occurs when dopamine levels in the brain reduce dramatically, it only makes sense that people living with Parkinson's are more likely to encounter depression. It is still not clear if there is a chain reaction that affects serotonin and norepinepherine levels in the Parkinsonian mind; but, there is some bias or strong suspicion in the medical community that people with Parkinson's are predisposed to suffer from serotonin and norepinepherine imbalances as well.
For the FDA to approve a drug, it has to show that it is safe and effective in the population that lives with the condition it claims to treat. In the case of paroxetine and venlafaxine, it is depression. The studies are large, intense and time consuming. However such studies rarely examine how safe and effective the drug is for other populations. So, when researchers tested venlafaxine they probably did not measure how effective it would be in the Parkinson's population. Clinical trials for paroxetine probably did not explore safety and effectiveness in people living with arthritis, diabetes, asthma and many other conditions. However, it is crucial for you and others with Parkinson's disease to know what medication is more likely to work well for you. By dramatically reducing the levels of dopamine in your brain, Parkinson's disease affects other chemicals in your central nervous system. So, it makes sense that we would want to look for ways to balance all of the chemicals, in addition to dopamine.
