bioRxiv (Cold Spring Harbor Laboratory),
Год журнала:
2024,
Номер
unknown
Опубликована: Дек. 17, 2024
Abstract
INTRODUCTION
Both
aging
and
Alzheimer’s
disease
(AD)
affect
episodic
memory
networks.
How
this
relates
to
region-specific
early
differences
in
functional
connectivity
(FC),
however,
remains
unclear.
METHODS
We
assessed
resting-state
FC
strength
the
medial
temporal
lobe
(MTL)
-
posteromedial
cortex
(PMC)
prefrontal
network
cognition
over
two
years
cognitively
normal
older
adults
from
PREVENT-AD
cohort.
RESULTS
within
PMC
between
posterior
hippocampus
inferomedial
precuneus
decreased
“normal”
(amyloid-
tau-negative
adults).
Lower
was
associated
with
poorer
longitudinal
performance.
Increasing
anterior
superior
related
higher
baseline
AD
pathology.
Higher
differentially
trajectories
depending
on
APOE4
genotype.
DISCUSSION
Findings
suggest
differential
effects
of
pathology
FC.
MTL-PMC
hypoconnectivity
cognitive
decline.
Furthermore,
hyperconnectivity
decline
carriers.
Graphical
abstract.
A)
“Normal
aging”
is
characterized
by
a
decrease
connectivity.
B)
Cognitively
unimpaired
more
at
(measured
via
cerebrospinal
fluid)
exhibit
increase
Nature Communications,
Год журнала:
2024,
Номер
15(1)
Опубликована: Июнь 5, 2024
Abstract
Our
current
understanding
of
the
spread
and
neurodegenerative
effects
tau
neurofibrillary
tangles
(NFTs)
within
medial
temporal
lobe
(MTL)
during
early
stages
Alzheimer’s
Disease
(AD)
is
limited
by
presence
confounding
non-AD
pathologies
two-dimensional
(2-D)
nature
conventional
histology
studies.
Here,
we
combine
ex
vivo
MRI
serial
histological
imaging
from
25
human
MTL
specimens
to
present
a
detailed,
3-D
characterization
quantitative
NFT
burden
measures
in
space
high-resolution,
atlas
with
cytoarchitecturally-defined
subregion
labels,
that
can
be
used
inform
future
neuroimaging
Average
maps
show
clear
anterior
poster
gradient
distribution
precise,
spatial
pattern
highest
levels
NFTs
found
not
just
transentorhinal
region
but
also
cornu
ammonis
(CA1)
subfield.
Additionally,
identify
granular
regions
where
neurodegeneration
are
likely
linked
specifically,
thus
potentially
more
sensitive
as
AD
biomarkers.
Abstract
Curing
Alzheimer’s
disease
remains
hampered
by
an
incomplete
understanding
of
its
pathophysiology
and
progression.
Exploring
dysfunction
in
medial
temporal
lobe
networks,
particularly
the
anterior-temporal
(AT)
posterior-medial
(PM)
systems,
may
provide
key
insights,
as
these
networks
exhibit
functional
connectivity
alterations
along
entire
continuum,
potentially
influencing
propagation.
However,
specific
changes
each
network
their
clinical
relevance
across
stages
are
not
yet
fully
understood.
This
requires
considering
commonly
used
biomarkers,
progression,
individual
variability,
age
confounds.
Here,
we
leveraged
monocentric
longitudinal
data
from
261
participants
spanning
adult
lifespan
continuum.
The
sample
included
cognitively
unimpaired
adults
aged
19
to
85
years
(n
=
209;
eight
out
64
older
over
60
were
Aβ-positive)
Aβ-positive
patients
fulfilling
diagnostic
criteria
for
mild
cognitive
impairment
(MCI,
n
26;
18
progressed
Alzheimer-dementia
within
seven
years)
or
type
dementia
26).
Participants
underwent
structural
resting-state
(f)
MRI,
florbetapir
FDG-PET,
global
assessments,
with
up
three
visits
a
maximum
period
47
months.
Network
was
assessed
using
seed-based
analyses
perirhinal
parahippocampal
cortices
seeds,
data-driven
masks
reflecting
AT
PM
networks.
Generalized
additive
linear
mixed
models
run
assess
age-specific
effects
Alzheimer’s-related
alterations.
In
this
context,
explored
various
markers
pathological
severity,
including
cerebral
amyloid
uptake,
glucose
metabolism,
hippocampal
volume,
cognition,
staging,
time
onset.
Our
findings
revealed
distinct
patterns
linked
normal
aging
disease.
Advancing
throughout
adulthood
associated
lower
more
subtle
connectivity,
while
characterised
hyperconnectivity
without
connectivity.
Specifically,
higher
MCI
compared
controls
positively
burden,
hypometabolism,
atrophy,
deficits
adults,
ranging
demented.
Additionally,
correlated
faster
progression
patients.
comprehensive
approach
allowed
reveal
that
excessive
is
intrinsically
These
insights
guide
future
research
better
understand
cascading
events
leading
hold
promise
developing
prognostic
tools
therapeutic
interventions
targeting
Frontiers in Neuroscience,
Год журнала:
2023,
Номер
17
Опубликована: Июнь 30, 2023
Introduction
Alzheimer's
disease
(AD)
is
a
neurodegenerative
that
significantly
impacts
the
quality
of
life
patients
and
their
families.
Neuroimaging-driven
brain
age
prediction
has
been
proposed
as
potential
biomarker
to
detect
mental
disorders,
such
AD,
aiding
in
studying
its
effects
on
functional
networks.
Previous
studies
have
shown
individuals
with
AD
display
impaired
resting-state
connections.
However,
most
used
structural
magnetic
resonance
imaging
(MRI),
limited
based
MRI
(rs-fMRI).
Methods
In
this
study,
we
applied
graph
neural
network
(GNN)
model
controls
predict
ages
using
rs-fMRI
AD.
We
compared
performance
GNN
traditional
machine
learning
models.
Finally,
post
hoc
was
also
identify
critical
regions
Results
The
experimental
results
demonstrate
our
can
normal
data
from
ADNI
database.
Moreover
differences
between
chronological
were
more
significant
than
controls.
Our
suggest
associated
accelerated
aging
connectivity
an
effective
tool
for
predicting
age.
Discussion
study
provides
evidence
promising
modality
research,
proves
be
Furthermore,
hippocampus,
parahippocampal
gyrus,
amygdala
are
verified.
Alzheimer s Research & Therapy,
Год журнала:
2025,
Номер
17(1)
Опубликована: Апрель 25, 2025
Abstract
Background
Both
aging
and
Alzheimer's
disease
(AD)
affect
brain
networks,
with
early
disruptions
occurring
in
regions
involved
episodic
memory.
Few
studies
have,
however,
focused
on
distinguishing
region-specific
effects
of
AD-biomarker
negative
“normal”
amyloid-
tau
pathology
functional
connectivity.
Further,
longitudinal
combining
imaging,
biomarkers,
cognition
are
rare.
Methods
We
assessed
resting-state
connectivity
(rsFC)
strength
graph
measures
the
memory
network
including
medial
temporal
lobe
(MTL),
posteromedial
cortex
(PMC),
prefrontal
alongside
over
two
years.
For
this
preregistered
study,
we
included
100
older
adults
who
were
tau-negative
using
CSF
PET
measurements
to
investigate
aging,
70
had
data
available
changes
related
AD
pathology.
All
participants
cognitively
unimpaired
from
PREVENT-AD
cohort.
used
region
interest
(ROI)-to-ROI
bivariate
correlations,
analysis,
multiple
regression
models.
Results
In
sample,
rsFC
within
PMC,
between
parahippocampal
inferomedial
precuneus,
posterior
hippocampus
precuneus
decreased
time.
Additionally,
observed
a
decrease
global
efficiency.
there
was
steeper
efficiency
higher
baseline
age
particularly
parahippocampal-gyrus
regions.
lower
PMC
associated
poorer
performance.
sample
data,
increase
anterior
superior
Higher
MTL-PMC
differentially
trajectories
depending
APOE4
genotype.
Conclusions
Our
findings
suggest
differential
Hypoconnectivity
cognitive
decline.
hyperconnectivity
decline
carriers.
Future
should
more
diverse
samples,
nonetheless,
our
approach
allowed
us
identify
pathology,
enhancing
cross-sectional
research.
Hyperconnectivity
has
been
proposed
as
mechanism
before,
now
contribute
specific
connections
focus
future
Graphical
A
)
“Normal
aging”
tau-
biomarker
status
characterized
by
strength.
B
Cognitively
Alzheimer’s
at
(measured
via
cerebrospinal
fluid)
exhibited
Communications Biology,
Год журнала:
2025,
Номер
8(1)
Опубликована: Май 25, 2025
The
transentorhinal
cortex
(tErC)
is
one
of
the
first
regions
affected
by
Alzheimer's
disease
(AD),
often
showing
changes
before
clinical
symptoms
appear.
Understanding
its
role
in
cognition
key
to
detecting
early
cognitive
impairments
AD.
This
study
tested
hypothesis
that
tErC
supports
fine-grained
representations
unique
individual
objects,
sensitively
granularity
demanded
discrimination,
influencing
both
perceptual
and
mnemonic
functions.
We
examined
tErC's
object
versus
scene
using
objective
(based
on
a
pretrained
convolutional
neural
network,
CNN)
subjective
(human-rated)
measures
visual
similarity.
Our
results
show
structural
integrity
specifically
related
sensitivity
similarity
for
but
not
scenes.
Importantly,
this
relationship
depends
how
measured:
it
appears
only
when
CNN
solely
ratings
discrimination.
Furthermore,
was
associated
with
tErC-BA36
connectivity,
computed
from
ratings.
Altogether,
these
findings
suggest
discrimination
may
represent
specific
marker
after
accounting
type
measured.
Frontiers in Aging Neuroscience,
Год журнала:
2024,
Номер
16
Опубликована: Апрель 24, 2024
To
investigate
the
abnormalities
of
three-dimensional
pseudo-continuous
arterial
spin
labeling
(3D
PCASL)
based
cerebral
blood
flow
(CBF)
correlation
networks
in
mild
cognitive
impairment
(MCI)
and
Alzheimer's
disease
(AD).
Abstract
This
study
extends
the
application
of
frequency-domain
new
causality
method
to
functional
magnetic
resonance
imaging
analysis.
Strong
causality,
weak
balanced
cyclic
and
transitivity
were
constructed
simulate
varying
degrees
causal
associations
among
multivariate
functional-magnetic-resonance-imaging
blood-oxygen-level-dependent
signals.
Data
from
1,252
groups
individuals
with
different
cognitive
impairment
collected.
The
was
employed
construct
directed
efficient
connectivity
networks
brain,
analyze
statistical
characteristics
topological
variations
in
brain
regions
related
impairment,
utilize
these
as
features
for
training
a
deep
learning
model.
results
demonstrated
that
accurately
detected
simulated
signals
degrees.
tests
also
confirmed
superior
performance
surpassing
other
three
methods
terms
accuracy,
precision,
recall
rates.
Furthermore,
consistent
significant
differences
observed
efficiency
networks,
where
several
subregions
defined
by
multimodal
parcellation
Human
Connectome
Project
simultaneously
appeared
patient
groups.
suggests
association
between
fine-grained
cortical
subregions,
driven
data
segmentation,
human
function,
making
them
potential
biomarkers
further
analysis
Alzheimer’s
disease.
Biological Psychology,
Год журнала:
2024,
Номер
192, С. 108847 - 108847
Опубликована: Июль 20, 2024
The
locus
coeruleus
(LC)
produces
the
neuromodulators
norepinephrine
and
dopamine,
projects
widely
to
subcortical
cortical
brain
regions.
LC
has
been
a
focus
of
neuroimaging
biomarker
development
for
early
detection
Alzheimer's
disease
(AD)
since
it
was
identified
as
one
earliest
regions
develop
tau
pathology.
Our
recent
research
established
use
positron
emission
tomography
(PET)
measure
catecholamine
synthesis
capacity
in
cognitively
unimpaired
older
adults.
We
extend
this
work
by
investigating
possible
influence
pathology
neurochemical
function
on
network
activity
using
functional
magnetic
resonance
imaging
(fMRI).
In
separate
sessions,
participants
underwent
PET
([18F]Fluoro-m-tyrosine),
([18F]Flortaucipir),
amyloid-β
([11C]Pittsburgh
compound
B),
fMRI
at
rest.
Consistent
with
growing
body
aging
preclinical
AD,
we
find
that
higher
is
associated
burden
individuals
risk
developing
AD
(amyloid-β
positive).
Critically,
relationships
between
tau)
were
moderated
capacity.
High
levels
reduced
Broadly,
these
findings
support
view
individual
differences
are
shaped
interactions
neuromodulator
function,
point
systems
potential
therapeutic
targets.