Alzheimer’s disease and the cocktail party effect

Alzheimer’s disease is mostly thought of as a memory problem. But as many who deal with the disease know, this isn’t the only problem people experience. Many patients come into clinic reporting difficulty following conversations in busy rooms, or hearing someone over a busy phone line. We’re trying to find out why people with Alzheimer’s have these problems, and what this can tell us about Alzheimer’s disease as a whole.

What is the cocktail party effect?

The cocktail party effect is a well-known phenomenon in psychology; it’s the ability to pay attention to a particular sound while many other sounds are going on at the same time. One good example of this is a cocktail party (hence the name). There are lots of people in the room all talking at the same time, as well as other sounds such as glasses clinking, footsteps and music. All these sounds come into our ears at the same time, but somehow our brains are able to unscramble all of these into something that makes sense, while also choosing which sounds we want to pay attention to. Psychologists have spent years studying this effect, and there is still a lot of research taking place to look at how our brains manage this difficult task.

Why study the cocktail party effect in Alzheimer’s disease?

My PhD at the Dementia Research Centre, Institute of Neurology, UCL, looks into how people with Alzheimer’s disease process sounds in the brain. One of my projects, funded by Alzheimer’s Research UK, is looking into how the brains of people with Alzheimer’s disease react to the cocktail party effect. We want to understand more about the symptoms people report in clinic. We think some areas of the brain that are affected by Alzheimer’s disease may also be the areas that we use to successfully cope with cocktail party-like situations.

How do we study this?

We use a technique called functional magnetic resonance imaging (fMRI). This measures the blood flow to certain areas of the brain. The more blood flowing to a certain area, the harder that area is working.

We take a group of volunteers with Alzheimer’s disease and a group of older adults without Alzheimer’s disease as comparison, and see how their brains react differently to cocktail party sounds. We then ask people to listen to different types of sound in the scanner, and measure their brain activity. The sounds we use are trying to mimic the exact types of cocktail party sounds we cope with in everyday life. For this we use the person’s own name over a background noise of many other people talking.

Example of sound

We hope this study will show us where in the brain people with Alzheimer’s react differently when hearing these types of sounds. So far we’re seeing some differences, but the study is still ongoing. This will give us more evidence about why people with Alzheimer’s find cocktail party situations difficult and help us understand this lesser-known group of symptoms. This could help people manage their environments better in social situations, such as picking a room with less background noise when catching up with family and friends. We also think that researching how sounds are processed in the brain will give us new insight into a network of brain areas we know to be affected in Alzheimer’s disease.

The area in yellow shows where we find brain activity for cocktail party sounds to be different in people with Alzheimer’s disease.

Visit the Dementia Research Centre website for more on their work.