Your brain works only as well as its blood supply.
Memory, focus, mood and sleep ride on the flow through the brain’s smallest vessels. COVID injures those vessels and lowers that flow, and by the end of 2023 almost 19 in 20 adults carried COVID antibodies, from infection or vaccination.1 One small-vessel injury now sits behind a wide spread of what gets treated as separate problems, from brain fog and attention to anxiety, low mood, broken sleep, migraine and the dementias. The largest study of post-COVID cognition measured the toll in points of IQ, scaling with how hard the infection hit.2 Those same vessels respond to what you do. That is what makes much of this preventable, and some of it reversible. Every claim sourced below.
One supply line, under everything.
Lower the blood reaching the brain’s smallest vessels, or raise the inflammation running through them, and a brain that was coping starts to drift. It is the same wiring under conditions that look unrelated on paper, which is why one short list keeps turning up as treatment for all of them.
ADHD, autism, anxiety and depression are dials, not switches. A diagnosis is a line drawn on a dial, and the shared pressures, less movement, more low-grade inflammation, and an infection almost everyone has now had, push people across it. The same things that restore blood flow carry them back.
Where to start.
COVID
How the infection injures small vessels, the cost measured in IQ points, and the vaccine answered straight.
Standing
Dizzy or foggy when you stand. POTS, long COVID, ME/CFS and hypermobility, one mechanism.
The ageing brain
Dementia, Alzheimer’s and whether your memory is ageing normally. What is preventable.
Neurodivergence
ADHD and autism as dials, not switches, and the blood flow that moves you along them.
Anxiety & mental health
When what gets called anxiety is the body briefly starved of blood.
Migraines
Weather, the falling barometer, and the inner-ear sensor behind the pain.
Menopause
Why perimenopause brings brain fog, and what the estrogen cushion was doing.
What helps
The free, best-proven ways to raise your own brain blood flow.
Keep your brain better supplied.
Most research on cerebral blood flow never reaches the people it could help. We read it and send only what changes what you can do: a new way to raise your own blood flow, or a finding that moves the advice on this page.
Ten studies worth your time
If you read nothing else here, read these. Most are open access, and the number after each jumps to its full entry in the list.
- Panic without a fear centre. Patients whose amygdala is destroyed feel no fear of outside threats, yet a lungful of CO2 still triggered full panic attacks, pointing to an alarm pathway in the body rather than the brain's fear centre. 3
- Same symptoms, different diagnosis. Shown identical filmed heart-attack symptoms, clinicians blamed a mental-health cause about twice as often when the patient was a woman, a controlled demonstration of bias rather than an anecdote. 4
- Told it was anxiety first. In a POTS patient survey, about 65 percent were told their symptoms were psychological and 45 percent were first diagnosed with anxiety. 5
- Training your way out of POTS. In a structured exercise programme, about 70 percent of patients who finished it no longer met the criteria for POTS, a hopeful result for a disorder usually framed as permanent. 6
- A wide perfusion gap. Brain imaging found women had higher blood flow than men in 67 of 68 regions, the largest sex difference in cerebral perfusion yet reported, which makes the abstract idea of brain blood flow concrete. 7
- The drop comes first. On standing, brain blood flow in POTS falls about 17 seconds before the racing heart and the sympathetic surge, marking low perfusion as the trigger rather than the result. 8
- Brain fog you can image. Arterial spin labeling MRI showed measurably lower cerebral blood flow in post-COVID patients with cognitive trouble, the most direct imaging evidence here that the symptom has a perfusion signature. 9
- Putting a number on it. A community study of roughly 113,000 people measured lasting drops in cognition and memory after COVID, with the largest deficits in those who had not recovered. 2
- Walking that rivals medication. A network meta-analysis found walking and running produced effects on depression comparable to antidepressants. 10
- Almost half is preventable. A standing Lancet commission estimates around 45 percent of dementia is potentially preventable through modifiable risks led by blood pressure and physical activity. 11