Older brains slow due to greater experience, rather than cognitive decline

What happens to our cognitive abilities as we age? Traditionally it is thought that age leads to a steady deterioration of brain function, but new research in Topics in Cognitive Science argues that older brains may take longer to process ever increasing amounts of knowledge, and this has often been misidentified as declining capacity.

The study, led by Dr. Michael Ramscar of the University of Tuebingen, takes a critical look at the measures that are usually thought to show that our cognitive abilities decline across adulthood. Instead of finding evidence of decline, the team discovered that most standard cognitive measures are flawed, confusing increased knowledge for declining capacity.

Dr. Ramscar's team used computers, programmed to act as though they were humans, to read a certain amount each day, learning new things along the way. When the researchers let a computer 'read' a limited amount, its performance on cognitive tests resembled that of a young adult.

However, if the same computer was exposed data which represented a lifetime of experiences its performance looked like that of an older adult. Often it was slower, not because its processing capacity had declined, but because increased "experience" had caused the computer's database to grow, giving it more data to process, and that processing takes time.

"What does this finding mean for our understanding of our ageing minds, for example older adults' increased difficulties with word recall? These are traditionally thought to reveal how our memory for words deteriorates with age, but Big Data adds a twist to this idea," said Dr. Ramscar. "Technology now allows researchers to make quantitative estimates about the number of words an adult can be expected to learn across a lifetime, enabling the team to separate the challenge that increasing knowledge poses to memory from the actual performance of memory itself."

Age Related Cognitive Decline All aging humans will develop some degree of decline in cognitive capacity as time progresses. Data indicates that deterioration of the biological framework that underlies the ability to think and reason begins as early as the mid twenties and includes a drop in regional brain volume, loss of myelin integrity, cortical thinning, impaired serotonin, acetylcholine, and dopamine receptor binding and signaling, accumulation of neurofibrillary tangles, and altered concentrations of various brain metabolites. Cumulatively these changes give rise to a variety of symptoms associated with aging, such as forgetfulness, decreased ability to maintain focus, and decreased problem solving capability. If left unchecked, symptoms oftentimes progress into more serious conditions, such as dementia and depression, or even Alzheimer’s disease.

Cognitive decline does not affect all individuals equally; clear associations exist between the rate and severity of cognitive decline and a variety of factors, including oxidative stress and free radical damage, chronic low-level inflammation, declining hormone levels, endothelial dysfunction, excess body weight, suboptimal nutrition, lifestyle, social network, other medical conditions, and various biomarkers. Fortunately, many of these factors are modifiable to a significant extent, and proactive lifestyle changes, cognitive training, and nutritional interventions have been shown to decrease the rate of intellectual decay and potentially reverse age-related cognitive decline.