Previously it had been suggested that there were no associated changes in the brain of individuals with ET. With data available for over 75 Essential Tremor Centralized Brain Repository (ETCBR) ET brains, researchers have already demonstrated that this is not the case. In fact, there seems to be at least two distinct types of changes in ET brains which indicate that there may be atleast two distinct types of ET.
The first possible subtype seems to be associated with the cerebellum, a region of the brain that controls movement and coordination. This subtype accounts for three quarters of the brains studied, and primarily consists of a loss of, and changes to,neurons in the cerebellum called Purkinje cells. As well, researchers noted that younger age in tremor onset, a positive family history of ET, and greater gait difficulty were more prevalent in these individuals.
The second subtype accounts for the remaining quarter of ET cases, and involves the presence of Lewy bodies in a specific structure of the brain called the locus coeruleus. Lewy bodies are abnormal accumulations of protein that gather insideof nerve cells, and have been associated with Parkinson’s disease (PD). As it is known that some individuals with ET go on to develop PD, this finding may offer key insights into a possible link between the two diseases. With more research, it may be possible to predict who with ET is at higher risk for developing PD.
Demands for a more accurate prognosis of the disease have been echoed by many individuals with ET, and the finding of possible subtypes of ET is a significant step forward in meeting those demands. This finding is also significant in the possibility it presents of improving treatment options for ET through the development of medications that target the specific-subtypes of ET.
The objective of the ETCBR is to expand upon these findings through the continued collection and study of brain tissue of individuals with essential tremor in order to develop these treatments and, eventually, find a cure. We are currently half way to reaching our goal of having 500 registered donors. With this many donors, we can expect approximately 8 new brains a year to study. The momentum we have developedwith these recent findings makes it especially important to reach that goal.
Two torpedos (marked with blue arrows). Torpedos are swellings on the Purkinje cell axon. These microscopic abnormalities are found in many ET brains.