// The Mailbag

“My knees are shot. Can I lift BDNF without sprints?” (Ray, 58)

Yes, and the bar sits lower than most folks think. A team at Boston University pooled 29 trials and 1,111 people. One bout of hard work lifted BDNF by a moderate step, not a small one.

Here is the fun part… folks who train often got a bigger spike from each bout. So the base you build feeds the peak. Hills, a row erg, a swim, a loaded cart up a ramp: all count. Your heart rate is the lever.

TRIALS: 29 · PEOPLE: 1,111 · ONE BOUT: g = 0.46

// The Mailbag

“Does the smell trick hold up at my age?” (Marion, 66)

Good catch, and the straight answer splits in two. That word pair trial ran on 165 adults aged 18 to 35. So it does not speak for you.

PEOPLE: 165 · AGE: 18 to 35 · SCENT: rose

But a team at UC Irvine ran the night half on your age group. Forty three adults, aged 60 to 85, slept with a diffuser by the bed. Seven oils, one per night, two hours each, six months long. The scent group beat the sham group on a word list test. That gap was wide… 226%. Scans showed a firmer link between the memory hub and the front of the brain.

PEOPLE: 43 · AGE: 60 to 85 · GAIN: 226% · SPAN: 6 months

// The Mailbag

“A friend sent me a cocoa pill ad. Junk?” (Dave, 61)

This is where I earn my keep. A deep research desk runs $20,000 a year for hedge funds. I read both trials, the small one and the big one.

Columbia ran the small one in 2014. Adults aged 50 to 69 drank a high flavanol mix for three months. Blood flow rose in the dentate gyrus. That is the part of the memory hub that fades first. They also got quicker on a picture task.

AGE: 50 to 69 · DOSE: 900 mg vs 45 mg · SPAN: 3 months

Then came the big test. COSMOS-Web gave 3,562 adults 500 mg of cocoa flavanols a day. At one year the main memory score held flat. But split that group by diet. One arm lit up… the folks who ate the least flavanol food to start with. So a pill may help fill a gap. It does not add a gift on top of a good plate. Eat dark cocoa and berries first. Save the pill for the weeks your plate runs thin.

PEOPLE: 3,562 · DOSE: 500 mg a day · YEAR 1: flat overall

// Reader Spotlight

FOUR NIGHTS, ONE JAR

Tom, 62, wrote in and started the same night. He is learning forty Polish words for a trip in the fall. His kit cost less than a plate of takeaway.

Tom says the morning quiz felt easier by the fourth day. That third arm of the trial used scent at all three points. It held the best score at day 28. I ran the loop with a jar of lemon peel while he did. My own recall on a Polish list felt sharper too. So I swapped to rose, to match the paper.

BEST ARM: learn + sleep + test · CHECKS: day 1, 7 and 28