Brain Health Alzheimers: what the experts say

The Big Picture

Four researchers who study the brain from different angles end up in a similar place: the things that protect memory with age are mostly ordinary health habits, and they are available to almost everyone. Dr. Charan Ranganath, a memory researcher speaking on Huberman Lab, admits that the most important factors are simply good health habits [3]. Dr. Wendy Suzuki, also on Huberman Lab, came to the same conclusion through her own life. After she started exercising she could focus longer and remember details more easily, and around the same time her father got lost driving home from a 7-Eleven seven blocks from their house and was later diagnosed with Alzheimer's dementia [4].

Two of the sources add something less expected. Dr. Lisa Mosconi, who directs the Women's Brain Initiative and is associate director of the Alzheimer's Prevention Clinic at Weill Cornell Medicine, tells Lewis Howes that women's brains age differently from men's, largely because of hormones, and that this helps explain why far more women than men develop Alzheimer's disease [1]. And Dr. Alan Castel describes the Nun Study, in which some nuns' brains showed the plaques and tangles of Alzheimer's disease after death even though they had functioned well cognitively in life [2].

Where the Experts Agree

Lifestyle does a lot of the work. Ranganath describes a study of 29,000 people in China followed for 10 years: those with four to six healthy lifestyle factors, such as cognitive activity, social engagement, exercise, healthy diet, not smoking and limited alcohol, performed almost twice as well on memory tests as those with zero or one [3]. Castel says that whatever protected the nuns may have been purpose, social connection, exercise, sleep or a positive attitude [2].
Exercise is on every list. Suzuki says every time you move your body you release neurochemicals such as dopamine, serotonin and noradrenaline, and that aerobic exercise also releases brain-derived neurotrophic factor, or BDNF, which helps new brain cells grow in the hippocampus [4]. Castel devotes part of his conversation to exercise, the brain and the overlooked importance of balance [2]. Exercise is one of the lifestyle factors in the study Ranganath cites [3].
Diet matters, and the Mediterranean pattern keeps coming up. Ranganath points to the Mediterranean-style diet and a Rush University study of a diet emphasizing leafy greens [3]. Mosconi covers the Mediterranean diet, plant-based eating, omega-3 fats, coffee, water and processed food [1].
Mood and connection are part of brain health. Ranganath says depression is terrible for memory, that he has seen depressed older adults more impaired than people with mild cognitive impairment, and that depression appears to be a risk factor for Alzheimer's [3]. Mosconi discusses the link between food and mood [1]. Castel lists social connection and attitude among the possible protectors [2].

Where They Differ

The sources largely agree. What separates them is emphasis.

What they lead with. Suzuki leads with aerobic exercise and its effect on the hippocampus and prefrontal cortex [4]. Mosconi leads with hormones and food, including menopause, hysterectomy and hormone therapy [1]. Ranganath leads with the combined effect of several habits [3]. Castel leads with the idea that something beyond brain pathology decides how people function [2].

How much certainty they claim. Suzuki is the most confident, saying regular exercise means "we all have the capacity to grow a bigger, fatter, fluffier hippocampus" [4]. Castel is more tentative. The nuns' protection was "possibly" purpose, connection, exercise, sleep or attitude, which is a list of candidates, not a finding about which one did it [2]. Suzuki's own family story, an inactive father who developed Alzheimer's and a mother who played team tennis into her 80s, is what made exercise a mission for her, but it is one family and not a study [4].

Who is most at risk. Only Mosconi makes sex differences central, arguing that hormones help explain why more women develop Alzheimer's [1]. Ranganath singles out older adults for a different reason: media multitasking is bad for memory, especially for older people, who are more distractible [3].

Normal aging versus warning signs. Castel alone separates the two. Older people retell stories partly because source memory declines with age, partly out of nostalgia and enjoyment, and partly because families pass on history that way. Repeating the same question minutes apart is different and more concerning [2].

Practical Takeaways

Do aerobic exercise regularly. Suzuki describes each workout as giving your brain "this wonderful bubble bath of neurochemicals" [4].
Stack habits instead of relying on one: stay mentally active, see people, exercise, eat well, don't smoke and limit alcohol [3].
Lean toward a Mediterranean-style diet with plenty of leafy greens [1][3].
Train your balance as you age, which Castel calls overlooked [2].
Take depression seriously in older adults and get it treated, since it harms memory and appears to raise Alzheimer's risk [3].
Cut back on media multitasking [3].
Women should treat menopause as a brain-health matter and learn the options, including hormone therapy, which Mosconi discusses [1].
Don't panic over a repeated story. Repeating the same question within minutes is the sign worth raising with a doctor [2].