The great Isaac Asimov once said:
“The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘huh, that’s funny’…”
Here at the Science of Parkinson’s disease we suspect that this was the situation when some Italian scientists made a curious discovery in some early-onset Parkinson’s disease subjects.
An image of a brain scan. Source: DailyMail
Last week they published their observation in the journal Movement Disorders:
Title: Abnormal Brain Temperature in Early-Onset Parkinson’s Disease
Authors: Rango M, Piatti M, Di Fonzo A, Ardolino G, Airaghi L, Biondetti P, & Bresolin N.
Journal: Movement Disorders, 2016 Mar;31(3):425-6.
The researchers were conducting brain scans of 5 people with early onset Parkinson’s disease (3 men and 2 women, with an average age of 41±6 years) and 10 control/normal subjects (6 men and 4 women with an average age of 43±7 years). The study was a follow on from a smaller previous study conducted by the same researchers. There was absolutely no difference in the average body temperature of all the subjects (36.7±0.48°C) and healthy subjects (36.5±0.84 °C).
But when the researchers began looking at different brains regions, they found there were substantial increases in temperature in the early-onset Parkinson’s patients when compared to the control subjects.
The areas of the brain where signiﬁcant temperature differences were observed included:
- the hypothalamus (38.50±0.20 vs. 37.01±0.60 °C; PD subjects vs controls)
- the posterior cingulate gyrus (37.60±0.20 vs. 36.70±0.40 °C)
- the centrum semiovale (38.00±0.60 vs. 36.60±0.60 °C)
- the lenticulate nucleus (38.80±0.80 vs. 37.40±0.60 °C)
There was also a slight difference in the visual cortex in the patient group, but this was not statistically signiﬁcant (37.20±0.20 vs. 36.80±0.40 °C).
Dysfunction in the hypothalamus is known to occur in Parkinson’s disease (click here for more information on this). Changes in the posterior cingulate gyrus (an area involved with emotion) have also been reported (click here for more information on this). But our knowledge of the role of the centrum semiovale and lenticulate nucleus in Parkinson’s disease requires further investigation.
Please remember that all things being equal, there should be no difference whatsoever in brain temperatures. The brain is an extremely sensitive organ and its temperature is rigidly controlled.
So why is there a difference?
Basically the researchers have no idea and, to their credit, they admit as much.
They also point out to the reader that any temperature change in the hypothalamus – an area of the brain that regulates temperature in the body – should result in a corrective response to restore proper temperature in the brain. But apparently in the early-onset Parkinsonian brain it doesn’t. They also note that dopamine-based Parkinson’s treatments (such as levodopa) should decrease overall brain temperature because they increase cerebral blood ﬂow (a natural cooling system for the brain). But again, this doesn’t appear to be happening.
They speculate that maybe these temperature differences are the result of ongoing disease-related activities in the brain, and they offer some well considered ideas as to why this maybe. But there are many other areas of the brain that are affected by Parkinson’s disease – why is there no change in temperature in those regions?
The researchers also ask whether cooling the brain may be considered as a therapeutic option. An interesting idea but this still needs to be tested. And the results of the current study also need to be replicated – independently validated by other groups.
In those replication studies it would be interesting to conduct the same experiment on people with Parkinson’s disease at different stages of the disease to see the effect is consistent or changing over time.
A curious result. Opening up new areas of research. And further evidence that it’s the ‘huh, that’s funny’ results that ultimately lead to the ‘Eureka!’ moments.