The more scientists learn about the brain, the more it appears that brain aging is not inevitable. Cognitive de-cline—once thought to be a normal aspect of growing older—may, in fact, be the product of un-healthy lifestyle choices that can be avoided.
“In the past decade or so, research has identified a number of factors that negatively affect mental fitness in older age,” says Maurizio Fava, Executive Vice Chair of the Department of Psychiatry at Mas-sachusetts General Hospital (MGH). “Some of these factors—such as genetic back-ground—are predetermined, but others reflect how people live their lives. These findings help point us to steps people can take to avoid and possibly reverse age-associated cognitive decline.”
In addition to adopting a healthy lifestyle, Dr. Fava advises taking particular care to avoid these five fac-tors, which are strongly linked to brain deterioration in older age:
#1 Mental Inactivity
“We have learned that the brain is resilient even in old age, and that avoiding mental inactivity and stimulating the brain can result in neurogenesis (the generation of new neu-rons) in brain regions important for thinking and memory,” Dr. Fava says. “One demonstration of the positive effects of mentally challenging activity is a recent study that suggests a type of working memory training called n-back training can improve cognitive skills over a short period of time.”
The researchers in that study measured levels of activity in the brains of older adults before and after they underwent n-back training, which involves attempting to remember recent items that appear on a computer screen, along with a number of items that have appeared previously.
The participants practiced n-back tasks (see What You Can Do) for one hour per day, five days per week, while a control group performed a non-training computer task for an equal amount of time. After five weeks, the trained participants had significantly increased the number of items they remembered and improved on several mental tasks for which they had not trained, while the control group had not. Measures of brain ac-tivity suggested that communication between two key brain regions—the parietal and frontal lobes—had improved in the trained participants, but remained unchanged in the control group.
“If additional studies support these findings, training programs may one day become clinically available for age-related cognitive decline,” Dr. Fava says. “Meanwhile, exercising the brain through a variety of challenging activities, such as puzzles, memorization, and taking courses, may help strengthen brain functioning.”
#2 Blood Vessel Damage
Type 2 diabetes, hypertension (high blood pressure), high levels of “bad” LDL cholesterol, and other negative factors affecting the blood vessels have a profound effect on brain health. Diabetes can weaken or damage small blood vessels in the brain, as can hypertension, which also damages cerebral white matter, the interconnected neuronal axons that serve as the brain’s communications network. A failing heart or cholesterol buildup that narrows blood vessels can injure or destroy neurons by depriving them of oxygen and nutrients. Heart arrhythmias can lead to blood clots and brain-damaging strokes.
“Regular exercise, a nourishing low-calorie diet with minimal saturated fats, weight control, and avoiding smoking are very important in maintaining a healthy heart and blood vessels,” Dr. Fava says. “Take steps to reduce stress, get treatment for depression and anxiety, and manage your glucose levels, blood pressure and cholesterol. If you already have cardiovascular problems, follow your doctor’s orders to minimize harm to the brain.”
Many older adults lose brain volume as they age, especially in the hippocampus, a key memory region, and the prefrontal cortex, where thinking and deci-sion-making are centered. This shrinkage is the result of a decline in the number of gray cells and neuronal con-nections, and is associated with poorer performance on cognitive tests. Hormones and proteins called growth factors—which help protect and repair neurons, regulate neuronal growth, stimulate the formation of new neuronal connections, and promote the survival of new neurons (neurogenesis) —normally decline with age.
“Any condition that results in the injury or death of brain cells or a decline in neurogenesis can lead to brain atrophy, so staying mentally and physically fit is the best way to limit brain shrinkage,” advises Dr. Fava.
His advice: Get regular exercise to increase the secretion of a prime growth factor in the brain called brain-derived neurotrophic factor (BDNF). Maintain healthy levels of glucose (blood sugar) through measures such as watching your weight, controlling your sugar intake, and taking medication, if necessary. High glucose levels common in prediabetes and diabetes are associated with reductions in insulin and insulin-like growth factor (IGF), as well as damage to cerebral blood vessels—both of which have been linked to brain atrophy and cognitive decline. Stay mentally active to increase neurogenesis, and avoid vitamin B-12 deficiency, a common cause of brain atrophy in older adults. Practice relaxation techniques to reduce stress, which can interfere with neurogenesis.
#4 Toxic Brain Plaques
A hallmark of AD is the accumulation in the brain of sticky plaques composed of toxic beta-amyloid. These plaques impair communication among brain cells and even-tually cause their death. Several factors are thought to play a role in this plaque buildup, including high-cholesterol diets, sleep deprivation, chronic inflammation in the brain, and insulin resistance and diabe-tes.
Among Dr. Fava’s suggestions: Treat high cholesterol with cholesterol-lowering medications, which appear to lower risk of AD. Seek help for sleep disorders. Disrupted sleep has been linked to the accu-mulation of beta-amyloid in the brain. Avoid chronic stress, which can cause the immune system to become overactive, resulting in brain-damaging inflammation. Follow medical advice for unhealthy rises in blood glu-cose levels.
#5 Sleep Disturbance
Chronic sleep deprivation (less than six hours of quality sleep at night) is associated with a number of negative brain effects. In addition to the accumulation of beta-amyloid, sleep dis-turbance has been linked with increased risk for stroke, abnormal behavior of brain cells, impairment of memory, concentration, and decision-making, increased risk for depression and anxiety, and reduced neurogenesis.
Dr. Fava’s advice: Practice good sleep hygiene (e.g., establish a restful environment, limit napping, restrict caffeine and other stimulants, and avoid alcohol and heavy meals close to bedtime). Seek help for causes of sleep disturbance, such as depression or anxiety, medical conditions that interfere with sleep, and sleep dis-orders such as insomnia and sleep apnea.