Eggs are recommended by dietary guidelines as an effective vehicle for DHA intake, yet direct evidence on the health effects and optimal dosage of egg yolk lipids against Alzheimer’s disease (AD) remains limited. This study evaluated DHA-enriched egg yolk lipids in 5×FAD mice at doses of 1 and 2 g/kg/day for eight weeks, corresponding to human consumption of 1 or 2 eggs daily. The high-dose intervention (2 g/kg) ameliorated cognitive deficits and neuronal damage by upregulating BDNF and NGF, improving synaptic plasticity (PSD95, SYN, Drebrin), increasing dendritic spine density, restoring cholinergic and glutamatergic neurons, and suppressing microglial activation-induced neuroinflammation (IL-6, IL-1β, IFN-γ). Metabolomic and gut microbiota analysis revealed increased levels of neuroprotective metabolites (PC(20:2/22:6), neuroprotectin D1) and enhanced abundance of AD-beneficial genera including Muribaculaceae and Lachnospiraceae. This study provides direct experimental evidence supporting DHA-enriched egg yolk lipids as a dietary intervention strategy for AD, with an effective dosage of 2 g/kg.
Well, mice.
The chance of interventions in mice models of AD carrying over to humans is not very high. I think it is worth saying that it is just on the hypothesis generating level. And we already had this hypothesis and it has failed - at the supplement level.
Now, there already is some human observational studies with eggs - attributed to choline rather than DHA by memory.
Now - if this study found high DHA eggs were better than normal DHA eggs, that might be something.
What’s DHA-enriched egg yolk? Eggs from chicken fed with a diet rich in omega 3?
I second what @DavidCary said. But yes, eggs are good 
In humans, we’ve observed that higher dietary intake of DHA is linked to a lower risk of Alzheimer’s. However, when it comes to actually improving cognitive function in Alzheimer’s patients, I doubt eating just one or two eggs a day will make much of a difference. Personally, I keep a habit of only eating half an egg a day.
To be honest, I’ve been sticking to just half an egg a day for years, but I’ve totally forgotten why I started doing it in the first place. I have a vague memory of it being related to some researchers’ models. But honestly, counting by the ‘number’ of eggs probably isn’t very precise—after all, some jumbo eggs are easily twice the size of smaller ones