Australian researchers have demonstrated that some dementia patients lose the emotional content of their memories, explaining how they can forget emotionally charged events like weddings or funerals.

A team from Neuroscience Research Australia discovered that a region of the brain called the orbitofrontal cortex plays an important part in linking emotion and memories.

It is well established that people more vividly remember events infused with emotion, such as birthday parties. But people with frontotemporal dementia (FTD) - a condition that affects the frontal and temporal lobes of the brain - have difficulty understanding and expressing emotion.

The research team showed patients images that prompt an emotional reaction in healthy people.

While healthy subjects and patients with Alzheimer's disease remembered more emotional than neutral images, FTD patients did not.