Do Stimulant Medications cause future development of Parkinson’s Disease?
Just in the last month, I was asked this question and therefore I thought that I may address the issue in depth here.
Parkinson’s disease (PD) is a diverse neurological disorder seen in relatively older aged population that affects cognitive function and produces tremors and poor motor coordination. Current research has shown that about 10 to 15% of PD seen in patients may be due to genetic factors. Current studies have discovered dozens of gene mutations linked to PD. There are many environmental causes playing a role in causing PD, such as head injury, pesticide and herbicide exposure, exposure to metals or solvents and polychlorinated biphenyls(PCBs), certain occupations, drug abuse and the area where you live. Currently, it is believed that genetics, environmental factors, and lifestyle choices collectively could be factors in PD. (Parkinson’s Foundation)
Since the mid-1930s, stimulants have been in use in the United States, starting with Amphetamines and then Methylphenidate. Millions of patients have taken this medication for ADHD and narcolepsy. It is considered as one of the main treatment for these conditions. In addition, there are few who have abused stimulants for recreational purposes, especially a toxic form, methamphetamine. Some studies have shown that about 5% of adults below age 35 years have used non prescribed amphetamine at least once. (National household survey on drug abuse: U.S. Dept. of Health and Human Services; Rockville, MD 2002.p32: 1998).
Concerns of some parents stem from current emerging studies suggesting a possible weak link between stimulant exposure and future development of PD. There is also a common link to PD and ADHD and they both have dopamine issue. Current therapies of PD and ADHD increase dopaminergic influence in the central nervous system.
Garwood et al published a study in Neurotoxicology in 2006 (Dec 27(6):1003-6) based on a telephone survey of patients having peripheral neuropathy, amyotrophic lateral sclerosis or PD between age 40 and 64. Their study showed that there was a statiscal difference in patients with PD.
Lappin published a review data in Drug Alcohol Depend 2018 and concluded that use of methamphetamine may be an initiating event for PD.
Ricaurte et al published a study in the Journal of Pharmacology and Experimental Therapeutics, 2005 showing amphetamine treatment similar to that used in the treatment of adult ADHD may cause changes in dopaminergic nerve endings in the striatum of adult primates.
More recently, Hanson, Curtin and their team published a study in the journal Neuropsychopharmacology in September 2018. Their team used the Utah Population Database (UPDP) and studied retrospectively 4960 patients with a diagnosis of ADHD and received stimulants. They found that a person who received stimulants was more than twice as likely to develop early-onset PD. However, the authors rightly cautioned that it could be due to the fact that these patients had a more severe form of ADHD and that carry a higher risk of developing PD.
There was a study presented at the American Academy of Neurology’s 63rd Annual Meeting in April 2011 which included 66,348 people from Northen California who had participated in the Multiphasic Health Checkup between 1964 and 1973 and were evaluated again in 1995. From this group, 1154 developed PD. In this study, those people reported the use of Benzedrine or Dexedrine were noticed to be more prone to the condition.
On the other hand, some researcher has used stimulants as a treatment for PD (Devos et al CNS Drugs 2013 27(1) 1-14.
It is easy to understand the concerns parents and professionals in this area. While review of the data suggests that there is a higher percentage of patients who received stimulants to develop PD, we need to note that people with ADHD are more prone to have PD and medications may not be the causative factor. We all should be cautious in this area and a prudent approach could be that if a child has mild symptoms of ADHD, then start with non-medicational modalities such as school-based help, counseling, complementary alternative approach. We should reserve drugs for more severe cases and those who do not respond to these alternative therapies. In those cases, stimulants are very important in the management of ADHD as many children respond well and achieve their full abilities, who otherwise would struggle in academics and may develop other issues such as poor self-esteem, anxiety, depression or school drop out.
See my informative video on stimulant medications here.
In conclusion, more definitive studies and research is needed in this field. We, at Brain Mind Body research lab are working on developing a blend that has natural non-medication products for helping children and adults with ADHD and they become especially important in light of these studies.
Please visit www.brainmindbody.com for periodic updates on various topics.
As always, I’d love to hear your comments below.
Dilip J. Karnik, MD
Founder of Brain Mind Body LLC