What happened
Russian President Vladimir Putin and North Korean leader Kim Jong Un signed an agreement Wednesday pledging some sort of mutual assistance if either country faced foreign "aggression." The pledge appears to be the strongest since the collapse of the Soviet Union ended a 1961 pact that required Moscow to step in if North Korea were attacked.

Who said what
Kim said the agreement, signed during Putin's first visit to North Korea since 2000, was the "strongest treaty ever" between Moscow and Pyongyang. Putin said the "breakthrough" pact "does not exclude the development of military-technical cooperation" — a statement analysts said could mean he will reward Kim's flow of munitions for the Ukraine invasion by helping to improve North Korea's nuclear missiles and other advanced weapons.

The scope of the agreement was unclear. South Korean analyst Cheong Seong Chang told The Associated Press it appears the two hermit states have "completely restored their Cold War-era military alliance." Moscow and Pyongyang are declaring a "de facto alliance," Hudson Institute security analyst Patric Cronin told The Wall Street Journal, but "there is nothing fundamentally new about this relationship today that was not true before Putin's visit."

What next?
Putin arrived in Vietnam on Thursday to bolster ties with Moscow's longtime ally and demonstrate the "diplomatic support Russia still enjoys in the region," the BBC said. 

What happened
A single copy of a rare genetic variant tied to Alzheimer's disease appears to delay the onset of cognitive impairment and dementia by about five years, U.S. and Colombian researchers reported Wednesday. The study, published in the New England Journal of Medicine, offers hope that a drug emulating this variant of the APOE3 gene, dubbed the Christchurch variant, could similarly defeat or delay Alzheimer's.

Who said what
Researchers reported in 2019 that a Colombian woman from an extended family genetically predisposed to develop Alzheimer's in their 40s had fended off dementia until her 70s, seemingly because she carried two copies of the Christchurch variant. The new study found that 27 relatives with just one Christchurch gene developed symptoms around age 52, roughly five years later later than other family members with the early-onset genetic mutation.

One patient could be a fluke, but "finding 27 people" evidently shielded by the Christchurch variant "increases our confidence in the discovery — and shows the results are reproducible," study co-author Joseph Arboleda-Velasquez, at Mass Eye and Ear in Boston, told The Washington Post. 

What next?
Researchers have found success testing an experimental drug that imitates Christchurch in mice and are seeking authorization for human trials.