Why it gets harder to remember as we get older

June, 2011

A new study finds that older adults have more difficulty in recognizing new information as ‘new’, and this is linked to degradation of the path leading into the hippocampus.

As we get older, when we suffer memory problems, we often laughingly talk about our brain being ‘full up’, with no room for more information. A new study suggests that in some sense (but not the direct one!) that’s true.

To make new memories, we need to recognize that they are new memories. That means we need to be able to distinguish between events, or objects, or people. We need to distinguish between them and representations already in our database.

We are all familiar with the experience of wondering if we’ve done something. Is it that we remember ourselves doing it today, or are we remembering a previous occasion? We go looking for the car in the wrong place because the memory of an earlier occasion has taken precedence over today’s event. As we age, we do get much more of this interference from older memories.

In a new study, the brains of 40 college students and older adults (60-80) were scanned while they viewed pictures of everyday objects and classified them as either "indoor" or "outdoor." Some of the pictures were similar but not identical, and others were very different. It was found that while the hippocampus of young students treated all the similar pictures as new, the hippocampus of older adults had more difficulty with this, requiring much more distinctiveness for a picture to be classified as new.

Later, the participants were presented with completely new pictures to classify, and then, only a few minutes later, shown another set of pictures and asked whether each item was "old," "new" or "similar." Older adults tended to have fewer 'similar' responses and more 'old' responses instead, indicating that they could not distinguish between similar items.

The inability to recognize information as "similar" to something seen recently is associated with “representational rigidity” in two areas of the hippocampus: the dentate gyrus and CA3 region. The brain scans from this study confirm this, and find that this rigidity is associated with changes in the dendrites of neurons in the dentate/CA3 areas, and impaired integrity of the perforant pathway — the main input path into the hippocampus, from the entorhinal cortex. The more degraded the pathway, the less likely the hippocampus is to store similar memories as distinct from old memories.

Apart from helping us understand the mechanisms of age-related cognitive decline, the findings also have implications for the treatment of Alzheimer’s. The hippocampus is one of the first brain regions to be affected by the disease. The researchers plan to conduct clinical trials in early Alzheimer's disease patients to investigate the effect of a drug on hippocampal function and pathway integrity.

Reference: 

Related News

Training in a mental imagery technique has been found to help multiple sclerosis patients in two memory domains often affected by the disease: autobiographical memory and episodic future thinking.

A study involving 218 participants aged 18-88 has looked at the effects of age on the brain activity of participants viewing an edited version of a 1961 Hitchcock TV episode (given that participants viewed the movie while in a MRI machine, the 25 minute episode was condensed to 8 minutes).

A study involving 100 healthy older adults (aged 60-80) has found that those with higher levels of physical activity showed more variable spontaneous brain activity in certain brain regions (including the

A ten-year study involving 2,092 older adults (average age 76) has found that people tended to lose awareness of memory problems two to three years before the onset of dementia.

A large, five-year study challenges the idea that omega-3 fatty acids can slow age-related cognitive decline.

A large, two-year study challenges the evidence that regular exercise helps prevent age-related cognitive decline.

A study involving 97 healthy older adults (65-89) has found that those with the “Alzheimer’s gene” (APOe4) who didn’t engage in much physical activity showed a decrease in hippocampal volume (3%) over 18 months.

An Indian study involving 648 dementia patients, of whom 391 were bilingual, has found that, overall, bilingual patients developed dementia 4.5 years later than the monolingual ones. There was no additional advantage to speaking more than two languages.

A study, involving 371 patients with mild cognitive impairment, has found that those with depressive symptoms had higher levels of amyloid-beta, particularly in the frontal cortex and the anterior and posterior

A study involving 206 spousal and adult children caregivers of dementia sufferers (mostly Alzheimer’s) has found that about 84% of caregivers reported a clinically significant burden. Three factors were significant contributors to the burden:

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news