Healthy Brain Aging

Healthy Brain Aging

The NINDS investigator community is passionate about discovering new and better ways of preventing and treating stroke as well as improving recovery in those who suffer stroke. High blood pressure, the primary driver of stroke, is thought to impart physiological damage on blood vessels in the brain. This damage can lead to ischemic and hemorrhagic stroke and even "silent strokes"—small infarcts that go relatively unnoticed, but which affect nearly 30 percent of elderly individuals. In addition to the well-known burden of illness due to clinical stroke, decades of research has also shown a causative link between stroke and cognitive impairment and dementia later in life.

"Given that high blood pressure causes its devastating impacts over time, it is important to control blood pressure in middle age, decades before most people become concerned about age-related cognitive loss."

Hypertension can also lead to "diffuse white matter disease" where the various bundles of fibers that connect brain regions are compromised by disease in the small blood vessels that supply the center of the brain. These abnormalities, which appear on MRI brain scans as coalescing, multiple bright spots in deep structures of the brain, affect as many as 80 percent of those over age 80, but their number, size, severity and rate of progression vary. Higher blood pressure levels over time have been linked to more extensive areas of white matter damage, which itself has been linked to diminished performance on tests of cognitive function.

Given that high blood pressure causes its devastating impacts over time, it is important to control blood pressure in middle age, decades before most people become concerned about age-related cognitive loss, in order to maximize the potential for protecting brain function later in life.

The National Institute of Aging (NIA), one of the 27 Institutes and Centers of NIH, leads a broad scientific effort to understand the nature of aging and to extend the healthy, active years of life. NIA is the primary Federal agency supporting and conducting Alzheimer's disease research. Ongoing research funded by NINDS and NIA is exploring the biological mechanisms that underlie the relationship between high blood pressure and other cardiovascular risk factors and the development of late life cognitive decline and dementia. NINDS staff reviewed current research on the link between high blood pressure and cognitive decline or dementia. I have posted that resource, called How stroke prevention promotes healthy brain aging to the NINDS blog.

New Report Brings Attention to Cognitive Aging

As the population of older Americans grows, cognitive aging—the gradual decline in abilities that affects everyone to some extent in the later stages of life—will place increased burden on individuals, their families, the healthcare system, and other social service networks. An April 2015 report by the Institute of Medicine (IOM) provides recommendations for research on the prevalence of cognitive aging, as well as methods of assessment, preventative strategies, and techniques for educating the public, healthcare practitioners, and the research community.

Unlike Alzheimer’s disease and other dementias, cognitive aging is a not a disease. It is a process of slow and steady, yet highly variable, changes in a number of cognitive functions that occur as people get older. However, there are simple protective measures—such as controlling high blood pressure—that may slow down this process.

A decline in cognition means more than forgetfulness. It covers a broad range of abilities including decision making, mental processing speed, memory, attention, and problem solving, each of which can decline at their own pace. These abilities are called upon for everyday living activities—including buying groceries, paying household bills, and driving to health care appointments—and a serious deterioration in these abilities can have an impact on an individual’s capacity for independent living.

The IOM brought together dozens of physicians, research scientists, and policy makers to discuss the gaps in our understanding of cognitive aging and ways to reduce the risk of decline. The heart of the report is a list of recommendations for action. See the end of this message for descriptions of the IOM’s other recommendations.

IOM recommendation: Increase Research and Tools for Assessing Cognitive Aging and Cognitive Trajectories

Studies using both human and animal brain tissue to investigate potential causes of cognitive aging have focused on number of brain cells, integrity of their connections, and properties of signaling chemicals. The results of these studies show that while the number of neurons remains relatively stable during cognitive aging—in contrast to the extensive neuron loss seen in Alzheimer’s—changes do occur in neuronal structure and neurotransmitter receptors.

The IOM report calls for increased research on measuring the physiological and structural basis of cognitive aging, including brain cell damage biomarkers (molecular signatures in the body that indicate the presence or severity of a medical condition),  brain imaging, and postmortem analysis of brain cell health. The IOM report also pointed to nonhuman animal studies as an important research direction that can be used to further examine the mechanisms of cognitive aging.

There are a number of interventions designed to maintain or improve cognitive functions in aging, but the research into the validity of these interventions and the mechanisms underlying their efficacy is lacking. The IOM recommends systematic evaluation of these interventions as well as efforts to develop improved interventions.

The IOM has also recommended additional research studies to identify and validate new tools for assessing cognitive function. To empower investigators to assess cognitive, as well as emotional, motor and sensory function—the NIH Blueprint has made available a collection of the most up-to-date validated assessment tools called the NIH Toolbox.

In presenting the recommendations from the IOM Committee on the Public Health Dimensions of Cognitive Aging, the committee chairperson noted that the group found more evidence to support the idea of reducing and managing cardiovascular risk factors (including high blood pressure, diabetes and smoking) to protect cognitive function than any other factor. A review of the evidence is available as an NINDS blog post titled: How stroke prevention promotes healthy brain aging.

Other recommendations from the IOM report include:

  • Collect and disseminate population-based data on cognitive aging

Having up-to-date population-based information on the nature and extent of cognitive aging can help build public awareness of the problem. This data can be used to engage older individuals and their families in discussions about maintaining cognitive health.

  • Actions to reduce the risk of cognitive decline with aging
  • Increase research on risk and protective factors and interventions
  • Promote cognitive health in wellness and medical visits

Additionally, the report recommends further research to identify any additional risk factors for cognitive aging, as well as research to find improved intervention and prevention strategies.

Physicians should discuss cognitive aging with their patients; explain risk factors and the difference between cognitive aging and Alzheimer’s. Doctors can also encourage patients to maintain a healthy lifestyle and regularly engage patients in a review of their medication plans.

  • Develop core competencies and curricula for health care providers and
  • Expand public communication efforts and promote key messages

The IOM recommends ways to inform both health care providers and individuals and their families of the most current information regarding risk factors and preventive/intervention strategies for cognitive aging.

  • Expand services to better meet needs of older adults and their families
  • Ensure appropriate reviews and policies for products making cognitive aging health claims
  • Develop consumer product evaluation criteria

There are a number of activities that various sectors of society should engage in to protect the cognitive health of aging individuals as well as protect those whose cognitive health has been compromised. The FDA and FTC can ensure appropriate review of products aimed at cognitive functioning. The CDC and NIH can come up with guidelines for evaluating individuals’ risk for cognitive decline with aging. Regulators of the financial industry can expand efforts to protect seniors from financial scams. Transportation authorities can help individuals and their families make decisions about whether it’s safe to keep driving as well as provide additional public transportation options.

Thursday, April 23, 2015