"Polyphenols can cross the blood-brain barrier (BBB), reduce neuroinflammation, and induce cell proliferation and adult-onset neurogenesis in the hippocampus."

Source: https://www.cravenherald.co.uk/news/national/uk-today/23769193.michael-mosley-says-green-tea-can-help-ward-off-dementia/?ref=rss

Radiation, unlike many cancer treatments, can cross that impermeable blood-brain barrier to treat recurring cancer and cancer that has spread to other parts of the body.

Source: https://www.dailymail.co.uk/health/article-12170125/Shannen-Doherty-reveals-breast-cancer-spread-brain-five-year-survival-rate.html?ns_mchannel=rss&ns_campaign=1490&ito=1490

The brain employs a protective shield known as the blood-brain barrier, which is designed to prevent harmful substances from violating the body’s control center.

Source: https://investorplace.com/2023/06/cash-in-on-the-longevity-boom-3-biotech-stocks-to-buy-now/

The drug was found to cross the blood-brain barrier – and achieved “a good level of penetrance into the brain”.

Source: https://thenewdaily.com.au/life/wellbeing/2023/01/22/cough-medicine-slows-parkinsons/

The SARS-CoV-2 spike protein alters barrier function in 2D static and 3D microfluidic in-vitro models of the human blood-brain barrier.

Source: http://fromthetrenchesworldreport.com/brain-injuries-after-covid-vaccination-by-colleen-huber/311000