Can reduced empathy be correlated with known physiological impacts of neurodegenerative and cerebrovascular diseases, such as cortical thickness and white matter hyperintensity, across a range of diseases?
This is a question that a group of researchers working with ONDRI’s Foundational Study dataset set out to explore.
Their results showed that there were in fact correlations between both cortical thickness and white matter hyperintensity (WMH) measures, and empathy deficits, when looking across all the disease cohorts that ONDRI studied.
These results were recently published in a paper entitled “Investigating the Contribution of White Matter Hyperintensities and Cortical Thickness to Empathy in Neurodegenerative and Cerebrovascular Diseases”, in GeroScience.
Empathy deficit and FTD
Although it has long been known that people living with frontotemporal dementia (FTD), especially behaviour variant FTD, can exhibit reduced empathy, this hasn’t been as well studied in other neurodegenerative and cerebrovascular diseases.
“Empathy is seeing with the eyes of another, listening with the ears of another and feeling with the heart of another.”
-Dr. Alfred Adler, founder of the school of individual psychology
Empathy is a social construct. It is best thought of as a skill that can be developed but, to differing degrees, comes naturally to most people. Empathy cannot be measured through a chemical or biological test like, for example, levels of cholesterol in the blood can. There are many parts of the brain that are accessed when one exhibits empathetic behaviour. This makes its study from a physiological sense of great interest.
Empathy involves perceiving something to have happened, then interpreting it and acting on it. This, by definition, involves different parts of the brain.
Many studies have linked lack of empathy to decreases in brain volume. This is intuitive; as brain cells lose their function, wither, and die, the brain shrinks, and the job that is performed by the affected part of the brain is impeded.
Brain shrinkage can be measured through brain volume measures including cortical thickness. But empathy, as above, is not controlled in just one part of the brain.
ONDRI researchers, working across the five disease cohorts studied, analyzed data from two platforms of the foundational study – neuroimaging and neuropsychology.
Specifically, they segmented study participants according to their results on the Interpersonal Reactivity Index (IRI) test, which has been validated to measure empathy in people living with Neurodegenerative (NDDs) and Cerebrovascular diseases (CVDs). Then they compared the IRI scores to neuroimages of the associated groups, looking for patterns of cortical thickness and white matter hyperintensity. Their conclusions:
Decreases in empathy were correlated with smaller cortical thickness, across the ONDRI cohorts (albeit to different extents). When white matter hyperintensity measures were taken into account, these correlation patterns were exacerbated.
What makes these results novel?
“What is unique here is that empathy reductions were noted across all the neurodegenerative diseases; and cortical thickness and white matter hyperintensity levels across diseases contributed to these deficits,” said Dr. Carmela Tartaglia, Cognitive/Behavioural Neurologist at the University Health Network in Toronto and the Senior author of this paper.
“We know that lesions in different parts of the brain have different impacts on measures of cognition, for example. Empathy is a distributed hub; there isn’t one central area of the brain where it’s controlled. In this study we’ve shown that losing brains cells has a devastating impact on empathy across all these diseases. And what’s more, when you layer in white matter hyperintensity, this makes the problem worse,” she continued.
When people think of a person living with Alzheimer’s disease, or post stroke, they don’t think that the person will likely exhibit a lack of empathy.
This study showed that this issue is broader than FTD and as lack of empathy has been shown to significantly contribute to caregiver burden, it should be accounted for in care protocols and other interventions across NDDs and CVDs.
WMH impact on empathy not related to CVD
As ONDRI’s cohort includes people living with CVD, which affects the blood vessels in the brain, we may expect that the WMH impacts observed would come mostly from this group.
“In fact, this is not the case,” said Miracle Ozzoude, the Lead author of the study and a Graduate Researcher at York University and Senior Neuroimaging Analyst at the Dr. Black Centre for Brain Resilience and Recovery Diseases. He continued: “The robust nature of the neuroimaging software allowed us to isolate the white matter hyperintensities associated with strokes (which is a major contributor to CVD). The CVD group did not drive these conclusions in our analysis.”
It is important to consider that two people may well have the same empathy measurement score on the IRI and as such, a similar reduction in empathy, but they could have gotten to that score based on completely different routes, when it comes to disturbances in the brain.
This ONDRI study confirms that degeneration across the brain in and of itself affects empathy levels for people living with NDDs and CVDs and that WMH is an exacerbator.