Highlights of 3 new studies in geriatric psychiatry include research on biomarkers to predict lifetime risk of Alzheimer disease; diet and brain tissue volume; and cognitive impairment in active older adults.
Biomarker screening tests for Alzheimer disease (AD) show lifetime risks of dementia vary considerably by age, gender, and the preclinical or clinical disease state of the individual. A multistate model for the disease process together with US death rates estimated the lifetime and 10-year risks of the potential that AD dementia will develop based on their age and screenings for amyloid deposits, neurodegeneration, and presence or absence of mild cognitive impairment (MCI) or any combination of those three factors.
Results: Men and women with a combination of all three factors (amyloid deposits, neurodegeneration, and presence or absence of MCI) are at the highest risk of developing AD. Lifetime risks for women are generally higher than men because they live longer.
Clinical Implications: Lifetime risks will help formulate screening guidelines to identify those who would be most helped by screening, especially in the preclinical stage. “What we found in this research is that people with preclinical AD dementia may never experience any clinical symptoms during their lifetimes because of its long and variable preclinical period. The high mortality rates in elderly populations are also an important factor as individuals are likely to die of other causes,” said lead author Ron Brookmeyer, PhD, from the UCLA School of Public Health, Los Angeles.
A quality diet leads to larger brain tissue volumes, suggesting that nutrition has an effect on neurodegeneration via brain structure. In a study of 4213 people who did not have dementia with an average age of 66 years, the participants were asked to complete a questionnaire about how much they ate of nearly 400 items over the past month. The best diet consisted of vegetables, fruit, nuts, whole grains, dairy, and fish, but a limited intake of sugary drinks. All participants had brain scans with magnetic resonance imaging to determine brain volume, the number of brain white matter lesions, and small brain bleeds.
Results: After adjusting for age, sex, education, smoking, and physical activity, a higher quality diet score was linked to larger total brain volume, when taking into account head size differences. Those who consumed a better diet had an average of 2 milliliters more total brain volume than those who did not. To compare, having a brain volume that is 3.6 milliliters smaller is equivalent to one year of aging.
Clinical Implications: “People with greater brain volume have been shown in other studies to have better cognitive abilities, so initiatives that help improve diet quality may be a good strategy to maintain thinking skills in older adults,” said senior author Meike W. Vernooij, MD, PhD, of the Erasmus University “Medical Center in Rotterdam, the Netherlands. “There are many complex interactions that can occur across different food components and nutrients and according to our research, people who ate a combination of healthier foods had larger brain tissue volumes.”
A moderate- to high-intensity aerobic and strength exercise training program does not slow cognitive impairment in older people with mild to moderate dementia. A multicenter, randomized controlled trial of 494 patients, average age 77 years, with dementia assigned 329 patients to an aerobic and strength exercise program and 165 patients to usual care. The program consisted of 60- to 90-minute group sessions in a gym twice a week for 4 months, plus home exercises for an additional hour each week with ongoing support.
Results: The exercise group showed improved physical fitness in the short term, but higher AD assessment score at 12 months compared with the usual care group, indicating worse cognitive impairment. However, the average difference was small and clinical relevance was uncertain.
Clinical Implications: “This trial suggests that people with mild to moderate dementia can engage and comply with moderate- to high-intensity aerobic and strengthening exercise and improve physical fitness. These benefits do not, however, translate into improvements in cognitive impairment, activities in daily living, behavior, or health related quality of life,” stated the researchers, led by Sarah E Lamb, of the University of Oxford, Oxford, United Kingdom.