Alzheimer's
____________________
is
an
irreversible
,
progressive
brain
____________________
that
slowly
destroys
memory
and
thinking
skills
,
and
,
eventually
,
the
ability
to
carry
out
the
simplest
tasks
.
In
most
people
with
____________________
,
symptoms
first
appear
in
their
mid
-
60s
.
Estimates
vary
,
but
experts
suggest
that
more
than
5
.
5
million
Americans
,
most
of
them
age
65
or
older
,
may
have
____________________
caused
by
Alzheimer's
.
Scientists
continue
to
____________________
the
complex
brain
changes
involved
in
the
onset
and
progression
of
Alzheimer's
disease
.
It
____________________
likely
that
changes
in
the
____________________
may
begin
a
decade
or
more
before
memory
and
other
cognitive
problems
appear
.
During
this
____________________
stage
of
Alzheimer's
disease
,
people
seem
to
be
____________________
-
free
,
but
____________________
changes
are
taking
place
in
the
brain
.
Abnormal
deposits
of
____________________
form
amyloid
plaques
and
tau
tangles
throughout
the
brain
.
Once
-
____________________
neurons
stop
functioning
,
lose
____________________
with
other
____________________
,
and
die
.
Many
other
complex
brain
changes
are
thought
to
play
a
____________________
in
Alzheimer's
,
too
.
