257 ‒ Cognitive decline, neurodegeneration, and head injuries: mitigation and prevention strategies

KEYPOINTS

• 01

  Some cognitive slowing with age is normal; dementia is an accelerated departure from that curve.

  Attia describes names that come back ten minutes late, something he didn't notice in his late 30s. Tommy Wood, a physician-scientist whose interests span lifestyle medicine, brain health and performance, separates this ordinary age-related drift in processing speed and recall from the steeper decline some people experience on the way to a dementia diagnosis. The goal of prevention is to stay on the gentle slope.

• 02

  The brain responds to the right kind and amount of demand.

  Wood argues cognitive function is use-dependent: novel, effortful and complex tasks build capacity, while retiring from all demand ('I'm 65, I'm done with spreadsheets') removes a key stimulus. Much of the evidence is observational, though he notes some interventional trials in older adults. There is also a threshold: overload, like Attia's unproductive 10 minutes of distracted work, achieves nothing.

• 03

  Task-switching carries a real cost.

  Refocusing after a switch takes on the order of 20-plus seconds, so someone changing focus every minute or two spends much of their time re-orienting. Wood suggests short blocks of single-task focus (perhaps 20–30 minutes) and walking breaks rather than constant juggling.

• 04

  Formula 1 is a model of performance under extreme cognitive load.

  Drivers hit straight-line speeds of roughly 200–220 mph while managing dozens of settings on the steering-wheel computer, and the jump in car complexity from F3 to F2 to F1 is large. Wood, who works in this environment, says the demands make it a natural laboratory for multitasking capacity and recovery.

• 05

  Alzheimer's is probably many diseases leaving the same 'tombstone'.

  Wood questions the amyloid-and-tau-centric view, noting that even Alois Alzheimer reportedly doubted whether his cases belonged together and that later genetic analyses of the original patient conflicted (one 2013 report claimed a PSEN1 mutation, another sample found none). His unifying view: homocysteine, poor omega-3 status, glucose hypometabolism and microvascular disease converge on a final common pathway of neuronal damage, with plaques and tangles as the residue.

• 06

  Research money is skewed away from modifiable risk.

  Wood cites the 2020 Lancet Commission estimate that about 40% of dementia may be attributable to modifiable risk factors, yet funding concentrates on late-stage pathology. He also notes the factors interact, so population-attributable risks shouldn't simply be added up.

• 07

  Lowering homocysteine slows decline and brain atrophy, especially with good omega-3 status.

  Elevated homocysteine has a suggested population-attributable risk around 20% for late-onset Alzheimer's. In the VITACOG trial (B12 and folic acid), lowering homocysteine slowed cognitive decline and atrophy, but atrophy slowed only in those in the top tertile of omega-3 status, and a Dutch study (B-PROOF) pointed the same way. Wood's evidence-based cutoff is 11 µmol/L; Attia's clinic targets 8–9 even though lab ranges call 13–14 normal.

• 08

  Poor omega-3 status may account for a similar share of risk.

  Another roughly 20% attributable risk has been assigned to low marine omega-3 intake. Both homocysteine and the omega-3 index are cheap and easy to measure. Wood frames moving homocysteine from 13–14 down to 9–10 while taking about 1–2 g/day of DHA as a potential 'winning lottery ticket', while stating it's not certain.

• 09

  Strength is one of the strongest protective associations.

  Comparing the strongest roughly 10% of people with the weakest 10%, Wood cites about a 70% lower incidence of and mortality from all-cause dementia. Grip strength is a proxy for whole-body strength, and resistance training in people in their 70s improves brain measures, likely through multiple pleiotropic effects.

• 10

  After a TBI, the first 24–72 hours are about preventing fever.

  Fever worsens secondary injury. Therapeutic hypothermia (33.5°C for three days) is standard for newborns with birth asphyxia, but in adult TBI the benefit seems to come from keeping core temperature at or below about 36.5°C. Wood suspects the early neonatal trials partly looked good because control babies were warmed quickly and left feverish.

• 11

  Hyperbaric oxygen is risky early and unproven later.

  Attia calls much of the hyperbaric industry 'a racket' outside indications like wound healing. Wood says that in the acute phase, extra oxygen in an inflamed, impaired brain may drive oxidative stress, and he has heard of unpublished work showing more adverse effects; any trial in the chronic phase would wait at least a couple of weeks, with only pilot data so far.