Deep loss of pleasure related to early-onset dementia

– Pleasure loss has been revealed as a key feature in early-onset dementia (FTD), as opposed to Alzheimer’s disease.

– Scans showed damage to the gray matter in the so-called pleasure system of the brain.

– These regions were distinct from those involved in depression or apathy – suggesting a possible treatment target.

People with early-onset dementia are often mistaken for depression, and now Australian research has found the cause: a profound loss of the ability to experience pleasure – for example, a delicious meal or a beautiful sunset – linked to the degeneration of “hedonic hot spots”. from the brain where the pleasure mechanisms are concentrated.

Research conducted by the University of Sydney has revealed marked degeneration or atrophy in the frontal and striatal areas of the brain related to decreased reward seeking in patients with frontotemporal dementia (FTD).

The researchers believe it is the first study to demonstrate profound anhedonia – the clinical definition of loss of the ability to experience pleasure – in people with FTD.

Anhedonia is also common in people with depression, bipolar disorder and obsessive-compulsive disorder and can be particularly disabling for the individual.

In the study, patients with FTD – which generally affects people between the ages of 40 and 65 – experienced a dramatic decline from the onset before the disease, unlike patients with Alzheimer’s disease who were not shown to have anedonia. clinically significant.

The results indicate the importance of considering anhedonia as a major feature of FTD presentation, where researchers found neural factors in areas that are distinct from apathy or depression.

The findings were published today in the main journal of neuroscience, Brain.

The lead author, Professor Muireann Irish of the University of Sydney, Brain and Mind Center and the Faculty of Psychology of the Faculty of Science, said that despite growing evidence of motivational disorders, no study had previously explored the ability to experience pleasure. in people with FTD.

“Much of the human experience is motivated by the desire to experience pleasure, but we often take this ability as such.

“But consider what it might be like to lose the ability to enjoy the simple pleasures of life – this has strong implications for the well-being of people affected by these neurodegenerative disorders.

“Our findings also reflect the functioning of a complex network of brain regions, signaling potential treatments,” said Professor Irish, who also recently published a paper in Brain about moral reasoning in FTD.

Future studies will be essential to address the impact of anhedonia on daily activities, and to inform the development of specific interventions to improve the quality of life in patients and their families.

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This is the first study, to the knowledge of researchers, that demonstrates deep anhedonia in FTD, reflecting the loss of gray matter density in the frontal and striatal regions of the brain. Interestingly, anhedonia was not present in a group of participants with Alzheimer’s disease, suggesting that this symptom is specific to FTD.

A total of 172 participants were recruited, including 87 FTDs, 34 participants in Alzheimer’s disease. Using brain imaging, the researchers found that the loss of pleasure related to degeneration in a discrete set of regions in the so-called pleasure system of the brain.

The study, conducted by the University of Sydney, includes researchers affiliated with the ARC Center of Excellence in Knowledge and Disorders, Prince Alfred Royal Hospital and the Black Dog Institute.

STATEMENT: The authors have no competing interests to declare.