Older minds distracted easily

“Mental slowing down in old age can be blamed partly on being more easily distracted,” BBC News online has reported.

This story is based on a small study that looked at brain activity during memory tests. Researchers asked 12 young people and 12 older people to remember pictures of strangers, while undergoing an MRI scan.

The results showed that the older group were worse at recalling faces and that parts of the older people’s brains seemed to be processing more background information than the younger group. The older people also appeared to be more easily distracted by the noise of the scanner than the young people.

However, this study cannot prove that more activity in the sensory areas of the brain is necessarily the cause of poorer recollection, although the link seems plausible. 

*Where did this story come from? *

This research was carried out by Dr W Dale Stevens and colleagues from Harvard University and the University of Toronto. The study was funded by the Canadian Institutes of Health and the National Institute on Aging. It was published in the peer-reviewed Journal of Neuroscience .

What kind of scientific study was this?

This was a cross-sectional study comparing brain activity in older and younger people during memory testing.

It is known that memory recall decreases with age. One theory is that this may be because older people are more easily distracted by their surrounding environment. If this were true, it could be expected that there would be extra activity in the sensory areas of older people’s brains as they tried to memorise things. Equally, the theory suggests this extra activity would be absent in younger people’s brains. The researchers aimed to test this theory.

The researchers enrolled 12 healthy older people (age range 64 to 78, average age 70 years) and 12 healthy younger people (age range 22 to 36, average age 26 years). People were not eligible to participate if they had any conditions that might impair memory, such as psychiatric, neurological or other medical illnesses, or a history of drug or alcohol abuse.

Participants’ cognitive function was assessed using a standard test to ensure that it was in the normal range before starting the study. Two of the older adults did not provide enough responses, and were excluded from the study.

Each participant was placed in an MRI scanner and shown a series of pictures of strangers’ faces. Some faces were shown more than once and participants were asked to press a button to indicate whether they had seen the face before or not. They also pressed a button to indicate whether they were certain about their judgement or not.

While they were performing this test, their brains were scanned to assess which areas were active. At the end of the tests, researchers compared brain activity in older and younger people when seeing faces that they subsequently remembered (hits) and when seeing faces that they subsequently forgot (misses). They also compared brain activity in the two groups for hits that the participants were certain and less certain about.

What were the results of the study?

The researchers found that the older participants recalled fewer faces than the younger participants.

In young people they found no significant differences in brain activity between looking at faces that were later recalled and looking at faces that were forgotten.

However, brain activity in older adults differed when they saw faces they subsequently remembered or forgot. When an older adult remembered a face, they had increased activity in the area of the brain involved in memory (the hippocampus).

When they did not remember a face, they showed increased activity in the area of the brain involved in hearing (the auditory cortex) and other areas that may be involved in monitoring the environment.

What interpretations did the researchers draw from these results?

The researchers concluded that environmental distractions, such as unfamiliar noises, may reduce older people’s ability to remember things. This means that it may be difficult to study memory in older people using MRI as the noises of the machine are too distracting to get accurate readings.

What does the NHS Knowledge Service make of this study?

This relatively small study has provided some insight into brain activity during memory tests in younger and older people.

However, just because there was more activity in the sensory areas of the older people’s brains it does not necessarily mean that this caused their reduced memory, although the link is plausible. These results come from a group of healthy older adults with normal cognitive function, and they may not apply to others who are less healthy or have some cognitive impairment.

It is hard to avoid distractions such as noise in everyday life. However, it seems sensible advice for anyone specifically trying to memorise information to reduce outside distractions such as noise whenever possible.