Memory decline linked to an inability to ignore distractions

Evidence is accumulating that age-related cognitive decline is rooted in three related factors: processing speed slows down (because of myelin degradation); the ability to inhibit distractions becomes impaired; working memory capacity is reduced.

A new study adds to this evidence by looking at one particular aspect of age-related cognitive decline: memory search.

A small study shows how those on the road to Alzheimer’s show early semantic problems long before memory problems arise, and that such problems can affect daily life.

Providing some support for the finding I recently reported — that problems with semantic knowledge in those with mild cognitive impairment (MCI) and Alzheimer’s might be rooted in an inability to inhibit immediate perceptual information in favor of conceptual information — a small study has found that executive function (and inhibitory control in particular) is impaired in far more of those with MCI than was previously thought.

A study involving 125 younger (average age 19) and older (average age 69) adults has revealed that while younger adults showed better explicit learning, older adults were better at implicit learning. Implicit memory is our unconscious memory, which influences behavior without our awareness.

A study involving young (average age 22) and older adults (average age 77) showed participants pictures of overlapping faces and places (houses and buildings) and asked them to identify the gender of the person. While the young adults showed activity in the brain region for processing faces (fusiform face area) but not in the brain region for processing places (parahippocampal place area), both regions were active in the older adults.

While brain training programs can certainly improve your ability to do the task you’re practicing, there has been little evidence that this transfers to other tasks. In particular, the holy grail has been very broad transfer, through improvement in working memory. While there has been some evidence of this in pilot programs for children with ADHD, a new study is the first to show such improvement in older adults using a commercial brain training program.

A study involving 155 women aged 65-75 has found that those who participated in resistance training once or twice weekly for a year significantly improved their selective attention (maintaining mental focus) and conflict resolution (as well as muscular function of course!), compared to those who participated in twice-weekly balance and tone training. Performance on the Stroop test improved by 12.6% and 10.9% in the once-weekly and twice-weekly resistance training groups respectively, while it deteriorated by 0.5% in the balance and tone group.

Research using data from a population-based birth cohort from Rotterdam, in The Netherlands, has found that children exposed to higher levels of air pollution when they were in womb had significantly thinner cortex in several brain regions. Some of this appeared to be related to impaired inhibitory control.

One important reason for the greater cognitive problems commonly experienced as we age, is our increasing difficulty in ignoring distracting and irrelevant information. But it may be that in some circumstances that propensity can be used to help memory.

A study involving 54 older adults (55-80), who possessed at least one risk factor for a stroke, found that those with white matter damage caused by silent strokes reported poor attentiveness and being distracted more frequently on day-to-day tasks. Despite these complaints, about half of these people scored within the normal range on tests of attention and executive function.

It’s suggested that adults who notice that they frequently lose their train of thought or often become sidetracked may in fact be displaying early symptoms of cerebral small vessel disease.