A decline in cognitive function could be indicated by a slower walking
pace, a more variable stride and other gait disturbances, according to five
studies presented at the Alzheimer’s Association’s International
Conference 2012.
“With an aging baby boomer generation advancing into greater risk
for Alzheimer’s and dementia, it is important for physicians to be aware
of the associations between gait and mental function. These studies suggest
that observing and measuring gait changes could be a valuable tool for
signaling the need for further cognitive evaluation,” William Thies,
PhD, chief medical and scientific officer of Alzheimer’s Association,
stated in the press release.
Basel center
Between 2007 and 2011, Stephanie A. Bridenbaugh, MD, of the Basel
Mobility Center at University Basel in Basel, Switzerland, and colleagues
tested spatio-temporal gait parameters among 1,153 older adults who had healthy
cognition (HC), mild cognitive impairment (MCI) or mild, moderate or severe
Alzheimer’s dementia (AD). Researchers used an electronic walkway to test
gait as a single task during normal walking speed, as well as during a working
memory and semantic memory dual task.
Study results showed that as cognitive impairment progressed, gait speed
slowed and was slowest during the semantic memory vs. working memory dual task
in participants with HC, MCI and mild AD. Gait cycle time variability remained
stable during the normal walking single task among participants with HC, MCI
and mild AD, but was at its highest during semantic memory dual task.
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“Mobility impairments are often associated with dementia, and some
gait changes may even appear before cognitive decline can be detected by
traditional testing methods. Gait analysis can simply, quickly and objectively
measure walking. When problems emerge, this may provide early detection of fall
risk and the earliest stages of cognitive impairment in older adults,”
Bridenbaugh stated in the release. “A gait analysis will not replace a
comprehensive neuropsychological assessment to diagnose a patient’s
cognitive status. Gait analysis, however, may prove to be an important tool to
aid diagnosis and record treatment effects or disease progression.”
Rotterdam study
In another study, 1,232 participants aged 49 years and older from the
Rotterdam Study were enrolled. Researchers used standardized neuropsychological
tests to measure information processing speed, memory, fine motor speed and
executive function, and gait was assessed using an electronic walkway, on which
participants performed a normal walk, a tandem walk and a turn. Gait variables
were then grouped into seven independent factors: rhythm, pace, phases,
variability, base of support, tandem and turn.
Overall, certain cognitive domains were only associated with certain
aspects of gait. For example, researchers found that information processing
speed was associated with the rhythm aspect of gait, whereas executive function
was associated with pace and variability and fine motor speed with tandem
walking. Memory was not associated with any aspect of gait, according to study
results.
MCSA
Researchers included 1,341 participants enrolled in the Mayo Clinic
Study of Aging (MCSA) who were examined with a computerized gait instrument at
two or more visits. Primary gait assessments included stride length, cadence
and velocity. The Short Test of Mental Status (STMS) and domain-specific
Z-scores calculated using nine neuropsychological tests covering four domains
— memory, attention/executive functioning, language and visuospatial
ability — were included in the outcomes.
Significantly larger declines in global cognition, memory and executive
function were found in participants with lower cadence, velocity and amplitude
of stride length, according to the study. Greater declines on the STMS were
also associated with lower gait measures. Researchers found an average decrease
in the STMS of 0.07 points per year associated with a 10 steps per minute lower
cadence and a STMS decrease of 0.5 points per year associated with a one meter
per second slower velocity.
“We observed an association between reduced gait velocity, cadence
and stride length and both global and domain-specific cognitive decline in our
population,” Rodolfo Savica, MD, MSc, of the Mayo Clinic, stated in
the release. “These results support a possible role of gait changes as an
early predictor of cognitive impairment.”
ISAAC study
Nineteen dementia-free participants underwent 3T brain MRI in the
Intelligent Systems for Assessing Aging Change (ISAAC) study. Lisa Silbert, MD,
MCR, of Oregon Health and Science University, and colleagues used FreeSurfer to
determine brain, ventricular and hippocampal volumes. Using an in-home
assessment system that continuously collected data using passive infrared
motion-activity sensors, gait speed was continuously assessed for one month
around the time of the MRI and compared with single gait speed determined on
the day of the patient’s MRI.
Researchers found that slower continuous in-home monitoring of gait
speed (CIHM-GS) was associated with decreased total brain, increased
ventricular and decreased hippocampal volumes, whereas single gait speed (SGS)
was only associated with hippocampal size. In two separate step-wise
regressions with age and gender as covariates, CIHM-GS was associated with
brain and cerebrospinal fluid. In a step-wise regression with hippocampal
volume as an outcome, only CIHM-GS remained related to hippocampal volume when
age, gender and SGS and CIHM-GS were covariates. Overall, mean SGS was 81.7
cm/sec and CIHM-GS was 76.4 cm/sec.
The Kurihara Project
More than 500 participants aged 75 years and older were enrolled in the
Kurihara Project in Kurihara and Osaki, Japan; 30% underwent volumetric MRI.
All participants walked 6 m at the fastest pace while researchers assessed gait
function using clinical measures including gait pattern, gait velocity and
stride length. Researchers classified gait patterns as normal, neurological
gaits and abnormal due to bone and joint disease.
Study results showed 73% of the participants had a normal gait pattern,
12% had a neurological gait and 14% had an abnormal gait due to bone and joint
disease. According to the Clinical Dementia Rating (CDR), 33% of the
participants were classified as CDR 0, 55% as CDR 0.5, 13% as CDR 1 or greater.
According to study results, gait velocity was significantly correlated with
atrophy of the bilateral medial temporal areas including the entorhinal cortex,
and decreased as CDR rating increased.
“Our research found that gait velocity was significantly decreased
as the severity of dementia symptoms increased,” Kenichi Meguro, MD,
PhD, of the Tohoku University Graduation School of Medicine in Sendai,
Japan, stated in the release. “Gait should no longer be considered a
simple, automatic, motor activity that is independent of cognition. They are
linked.” — by Casey Murphy
For more information:
Bridenbaugh S.P1-073.
Ikram M.O1-08-02.
Mielke M.P2-169.
Silbert L.P2-022.
Tanaka N.O1-08-05. All presented at: the Alzheimer’s
Association’s International Conference. July 14-19, 2012; Vancouver,
British Columbia, Canada.
Disclosure: Bridenbaugh, Meguro, Savica and Silbert had no relevant
financial disclosures.
