How Exercise, Diet, Sleep, and Hearing Affect Brain Aging

Exercise, diet, sleep, and hearing are 4 major factors that impact our aging, said Stephen M. Stahl, MD, PhD, adjunct professor of psychiatry, University of California San Diego during a session at the 2017 Neuroscience Educational Institute (NEI) Congress.

“In normal aging, our brains slow down,” said Stahl. “Intelligence remains stable, but we become less mentally flexible. We have longer processing time and declines in motor, sensory, and cognitive abilities.”

Aging is known to have deleterious effects on cerebral white matter. There is shrinkage of white matter tissue, which may be due to alterations in myelin (demyelination).

Stahl, who is also the NEI chairman, first focused on the relationship between exercise and aging. Activity levels for 1740 participants in a cohort study of people 65 and older were examined over 6.2 years. Results found a 32% reduction in risk of dementia for participants who exercised 3 or more times per week compared with those who exercised less than 3 times per week.

A recent meta-analysis suggests that there overall benefits from aerobic exercise on episodic memory, attention, procession speed, and executive function in non-demented older adults, said Stahl. Both single bouts of brief moderate-intense exercise and long-term, repeated bouts of mild exercise have resulted in improved cognitive performance and memory in normal aging and patients with mild cognitive impairment (MCI).

Stahl focused on 2 diets when discussing the relationship between dieting and aging: the Dietary Approaches to Stop Hypertension (DASH) and the Mediterranean Diet (MediDiet). Both diets recommend high consumption of fruits, vegetables, legumes, nuts, and low amounts of red or processed meats.

The DASH diet focuses more on low-fat dairy and is associated with better cognitive function in older adults and less cognitive decline over time. The MediDiet focuses more on olive oil and wine and is associated with slower cognitive decline, improved cognitive function, and decreased risk of dementia.

Sleep and wake disorders are prevalent in older adults, with ~50% having insomnia and ~50% having sleep disordered breath, said Stahl. Sleep deprivation increases the deposition of beta amyloid. Meanwhile, during slow wave sleep, amyloid beta is cleared more effectively.

“Hearing loss affect about two-thirds of individuals aged 70-plus in the US,” said Stahl.

Hearing loss is associated with brain atrophy and neurodegeneration, especially in the temporal cortex. Over a 10-year period:

• Mild hearing impairment = 2x increased risk of dementia
• Moderate hearing impairment = 3x increased risk of dementia
• Severe hearing impairment = 5x increased risk of dementia

Treating hearing impairment may lead to cortical restructuring and cognitive improvement, said Stahl.

“Lifestyle behaviors can alter neuroplasticity in detrimental or beneficial ways,” concluded Stahl. “Sleep deprivation can have detrimental effects on aging, treating hearing loss can result in cortical restructuring, and exercise and specific diets may result in delayed cognitive impairment and may preserve brain health.”