Larry W. Chambers is Research Director at McMaster University's Niagara Regional Campus, School of Medicine
Eric Larson committed his career to researching how to delay and prevent Alzheimer’s disease, other forms of dementia, as well as declining memory and thinking. He led the “Adult Changes in Thought study”, which began following a large general population cohort in 1986. It has one of the largest research populations that included individuals aged 85 years and older.
Larson’s new book, “,” coauthored with professional writer and journalist Joan DeClaire, is based on information from hundreds of research papers Larson has authored and co-authored. The reader benefits from his profound understanding of health and aging research and his clinical experience as a practicing physician. Evidence is presented alongside useful patient stories to aid comprehension, engagement and to pique the reader’s interest.
In a chapter entitled “Building Your Mental Reserves: Strengthening the Mind/Whole-Body Connection”, which discusses how to prevent dementia, Larson begins by referring to the increased awareness of dementia in America after President Ronald Regan was diagnosed with Alzheimer’s disease in 1994. The general public’s perception was pessimistic regarding any delay and prevention for Alzheimer’s disease and dementia. However, Larson makes the case that there is cause for optimism. Cognitive research has shown that the natural loss of connections in the brain can be delayed and also reversed. The brain is capable of growing new cells and making new connections to regenerate damaged brain cells.
While the genetic foundations of early onset Alzheimer disease – that is, disease that begins before age 65 - is known, the role of genetics is not clear for people who develop Alzheimer dementia after age 75 years. Those aged older than 75 comprise more than 90% of the population who have dementia. After examining this evidence, Larson concludes that genetic testing for Alzheimer’s disease is not justified.
Larson also argues that research on Alzheimer’s disease has not progressed in a linear fashion because researchers were not studying the right people in the right settings. The concept ‘platelet membrane fluidity’ and the detection of amyloid protein deposits in blood vessels and other tissues are provided as examples of ‘discoveries’ that could not be replicated in larger, more typical and diverse community-based populations.
Larson presents persuasive evidence that there is a healthy brain/healthy body connection. Research shows that autopsies of brains from people who had Alzheimer disease typically showed other degenerative pathology as well. , The condition called ‘mixed dementia’, which is Alzheimer disease and vascular disease combined, is common among those aged 75 and older. Larson reminds us that brain health begins early in life with early childhood brain stimulation and development. Research has shown that exposure to maternal smoking and alcohol before birth and during early childhood is associated with an increased risk of Alzheimer disease eighty years later.
Indeed, one of the main themes in Larson’s book is that lifestyle affects the reservoir of brain power. During a lifetime, brain power is determined by family, education, career, social network and leisure time. Larson states that there is evidence to show brain power reserve increases with learning. He gives the example that there is more brain power reserve created when changing jobs from a reservation clerk to an accountant than there is from changing jobs from a dishwasher to a reservation clerk. However, brain games such as Sudoku, traditionally touted to ‘train the brain’, appear to have limited effect on the reservoir of brain power. Larson discusses the results of the ACTIVE trial, which seemed to show promise of cognitive stimulation, but points out that other studies show that practice of specific cognitive tasks may not transfer into long-term benefit in other areas of cognitive performance.
Larson calls physical activity ‘the brain’s best friend’, referring to his study, , which showed that people aged 65 and over who exercised three or more times a week had 30 to 40% lower risk of developing dementia than those who exercised less often than three times a week. He points out that even the frail person benefits from gentle exercise, such as walking for 15 minutes a day.
But protecting the brain from injury and other neuropathological risk factors is also important according to Larson. Protecting oneself against head injury, drinking alcohol moderately, being aware of and addressing cardiac risk factors, avoiding a high-sugar diet, limiting stress and sleeping well, all go a long way towards protecting against the development of dementia.
Larson points out that frequently older people who experience symptoms of cognitive decline think, fatalistically, that there is nothing that can be done to help. They may begin to withdraw from activities, reduce intellectual pursuits, and cease taking disease-modifying essential drug therapies that are actually helping to maintain their cognitive fitness. As a result, the person may become depressed, isolated and less physically active, which leads to a vicious cycle whereby brain and physical fitness decrease more quickly.
In “Enlightened Ageing”, Larson offers hope and practical insights into how to build both brain and physical resilience through living a healthy life, and challenges us to change fatalistic attitudes to dementia.