Your Old Brain Is Too Full to Learn Anything New, So Go Ahead
and Call It a DayS  If you're having trouble taking in new
information as you get older, don't fret. It's not that age is
making you more stupid or slow, but that your brain is already
so full of information — you genius, you — that it can't make
room for anything new.  After studying mice with brains that had
been genetically altered to resemble an adult human's,
neuroscientists at the Medical College of Georgia at Georgia
Regents University have recently discovered that the human brain
does not necessarily decrease in its ability to make the strong
synaptic connections that allow us to learn as we get older.
Rather, as the brain ages, it finds it harder to weaken older
memories and solidify new ones.  From the New York Times:  Think
of it as writing on a blank piece of white paper versus a
newspaper page, said the lead author, Joe Z. Tsien. "The
difference is not how dark the pen is," he said, "but that the
newspaper already has writing on it."