A loss of empathy in people diagnosed with younger-onset dementia is related to grey matter loss in the ​‘social brain’, according to new research published in the Journal of Alzheimer’s Disease.

Early loss of empathy is one of the core symptoms of behavioural-variant frontotemporal dementia (bvFTD), which is often diagnosed when people are in their 50s. In contrast, empathy remains relatively intact in people with Alzheimer’s disease (AD). People with bvFTD are often unaware of the impact of their behaviour on others, causing strain on close relationships.

The study, conducted by NeuRA researcher Dr Muireann Irish, found that both the ability to understand other people’s emotions (cognitive empathy) and to share in other people’s feelings (affective empathy) were decreased in people with bvFTD. People diagnosed with Alzheimer’s however, retained the capacity for affective empathy.

“Cognitive empathy is the ability to understand another person’s emotional state. It allows you to pick up on someone else’s mood, whether it be happy, fearful, or concerned,” says Dr Irish. ​“Affective empathy is the ability to share and respond appropriately to another person’s emotions, for example offering someone a kind or compassionate word if you sensed they needed it.”

The loss of either of these two types of empathy can have a profound impact on the patient-caregiver relationship, Dr Irish said.

The study used neuroimaging analyses to understand which areas of the brain related to loss of empathy in bvFTD and AD. It found that a core social processing area of the brain displayed pronounced deterioration in bvFTD. This area, however, remained largely intact in AD patients.

These new findings offer important insights into the neurocognitive mechanisms that underlie many of the emotional changes in bvFTD. Importantly, it can lead to understanding how caregivers may better deal with these changes.

How was this study conducted?

• Empathy was investigated in a total of 71 participants who attended FRONTIER, the frontotemporal dementia clinic at Neuroscience Research Australia (NeuRA) in Sydney.
• Each patient’s carer completed the Interpersonal Reactivity Index to assess the capacity for cognitive and affective empathy.
• Carer ratings of a patient’s level of empathy were obtained for two time points: (i) before the illness, and (ii) at the present time.
• Voxel-based morphometry (VBM) using MRI data was used to identify how reduction in grey matter volume related to loss of empathy in each patient group.

Watch Dr Muireann Irish talk about this research on ABC News.