Could Environment, Diet, or Work Have Caused My PSP?

It is natural to look for a reason when you are diagnosed with a progressive condition like Progressive Supranuclear Palsy (PSP). Many patients wonder if a past diet, lifestyle choice, or workplace exposure is to blame. The direct answer is that for the vast majority of people globally, no specific toxin, diet, or lifestyle factor has been proven to cause PSP ^[1]. While researchers hypothesize that environmental exposures may trigger the disease in genetically susceptible individuals, most cases remain unexplained by a single identifiable cause ^[1][2].

The Search for Environmental Triggers

Medical researchers have investigated several potential environmental risk factors to understand how they might contribute to the abnormal buildup of tau protein—the hallmark of PSP. Much of this research focuses on substances that might damage the mitochondria, the energy-producing centers of our cells.

The Guadeloupe Connection and Soursop

One of the most significant discoveries regarding environmental triggers came from the French Caribbean island of Guadeloupe. Researchers noticed an unusually high rate of atypical parkinsonism (a group of brain disorders that share some symptoms with Parkinson’s disease but are distinct and do not respond as well to typical medications) among the local population. Studies linked these cases to the heavy consumption of soursop (also known as Annona muricata or guanabana) as both a fruit and in herbal teas ^[3].

Soursop and related fruits contain a natural chemical called annonacin. Annonacin is a potent mitochondrial inhibitor, meaning it disrupts the cells’ ability to produce energy ^[4]. Animal studies have shown that consuming annonacin can accelerate the buildup of abnormal tau protein in the brain ^[5].

While regular soursop consumption is extremely rare for most PSP patients globally, as a precaution, it is generally advised that people with PSP and their family members avoid consuming soursop fruit or teas. Note that standard grocery store papaya (sometimes called “pawpaw” in regions like Australia and the UK) does not contain annonacin and is perfectly safe. However, the North American pawpaw tree (Asimina triloba) does contain similar compounds, and its heavy consumption should also be avoided.

Industrial and Occupational Exposures

Outside of the Caribbean, researchers have occasionally found localized “clusters” of PSP that point to potential environmental factors. For example, an unusually high concentration of PSP cases was identified in a specific region of northern France ^[6]. This geographical cluster was located in an area with a long history of severe environmental contamination from industrial metals, including chromate and phosphate ore processing, textile dyeing, and leather tanning ^[6].

However, studies of this cluster noted that nearly all the affected individuals also carried a specific genetic susceptibility known as the tau H1 haplotype ^[6]. This suggests that heavy metal or industrial exposures might trigger PSP, but likely only in people who are already genetically predisposed. It is important to note that the tau H1 haplotype is very common in the general population; having it does not mean your children or family members will develop the disease.

Furthermore, widespread studies have not consistently linked everyday occupational exposures—such as farming, pesticide use, or typical manufacturing jobs—to the development of PSP ^[1][2]. While drinking well-water is sometimes investigated in relation to standard Parkinson’s disease, it has not been definitively linked to PSP.

Finding Peace with the “Why”

Looking back over a lifetime to find something to blame is a common and completely understandable reaction. You might worry about a specific chemical you worked with decades ago or a particular diet you followed.

However, the current medical consensus is clear: there is no single proven environmental cause for the vast majority of PSP cases. The disease is complex, likely requiring a combination of genetic predisposition and unknown, cumulative environmental factors over a lifetime. You did not cause your PSP by eating the wrong foods, choosing the wrong profession, or living in the wrong place.