Personalized tDCS in Elderly Fallers Study
| Status: | Not yet recruiting |
|---|---|
| Conditions: | Healthy Studies |
| Therapuetic Areas: | Other |
| Healthy: | No |
| Age Range: | 65 - 85 |
| Updated: | 1/26/2019 |
| Start Date: | March 1, 2019 |
| End Date: | March 1, 2023 |
| Contact: | Ted Gruen |
| Email: | gruen@hsl.harvard.edu |
| Phone: | 617-971-5334 |
Personalized Brain Activity Modulation to Improve Balance and Cognition in Elderly Fallers
The objective of this study is to determine if a four-week, 20-session intervention of
personalized transcranial direct current stimulation (tDCS), as compared to sham
intervention, improves dual task standing and walking performance (Aim 1), as well as other
physical (Aim 2) and cognitive (Aim 3) factors on the causal pathway to falls, in older
adults who report two or more falls within the past year and fear of falling again in the
future, yet who do not have any acute or over neurological or musculoskeletal condition.
Primary endpoints will include the "dual task" costs to gait speed when walking and postural
sway speed when standing, as induced by performing a serial subtraction cognitive task (i.e.,
[(speeddual task - speedsingle task) / speedsingle task) X 100] (Aim 1), the Short Physical
Performance Battery (Aim 2), and the Trail Making Test (Part B minus Part A) (AIM 3).
Secondary endpoints will include the dual task cost to serial subtraction performance,
additional gait and balance outcomes derived from the dual task paradigm, the Timed
Up-and-Go, fear of falling, habitual physical activity, and performance within a battery of
neuropsychological tests focused on global cognitive function, attention, verbal fluency and
memory.
personalized transcranial direct current stimulation (tDCS), as compared to sham
intervention, improves dual task standing and walking performance (Aim 1), as well as other
physical (Aim 2) and cognitive (Aim 3) factors on the causal pathway to falls, in older
adults who report two or more falls within the past year and fear of falling again in the
future, yet who do not have any acute or over neurological or musculoskeletal condition.
Primary endpoints will include the "dual task" costs to gait speed when walking and postural
sway speed when standing, as induced by performing a serial subtraction cognitive task (i.e.,
[(speeddual task - speedsingle task) / speedsingle task) X 100] (Aim 1), the Short Physical
Performance Battery (Aim 2), and the Trail Making Test (Part B minus Part A) (AIM 3).
Secondary endpoints will include the dual task cost to serial subtraction performance,
additional gait and balance outcomes derived from the dual task paradigm, the Timed
Up-and-Go, fear of falling, habitual physical activity, and performance within a battery of
neuropsychological tests focused on global cognitive function, attention, verbal fluency and
memory.
In older adults, falls are costly, consequential and correlated with both physical and
cognitive decline. Most falls occur when standing or walking. Many activities require people
to stand or walk while performing tasks like talking or making decisions. Such "dual tasking"
interferes with the control of standing and walking. This interference, or "cost," is
exaggerated in older adults with previous falls and is predictive of future falls.
Neuroimaging evidence indicates that standing and walking,especially when dual tasking,
activate distributed brain networks including the left dorsolateral prefrontal cortex
(dlPFC)—a brain region sub-serving executive function. Thus, strategies that facilitate
activation of the left dlPFC and its connected neural networks hold promise to mitigate dual
task costs, improve physical and cognitive function, and ultimately, reduce falls.
Transcranial direct current stimulation (tDCS) provides a noninvasive means of selectively
modulating cortical excitability. The investigators have shown in younger and older adults
that a 20-minute session of tDCS designed to increase excitability of the left dlPFC reduces
dual task costs and improves mobility when tested just after stimulation. The investigators
have since completed a pilot, sham-controlled trial of a 2-week, 10-session tDCS intervention
targeting the left dlPFC in 20 older adults with slow gait and mild-to-moderate executive
dysfunction. The intervention was successfully double-blinded and well-attended. tDCS,
compared to sham, reduced dual task costs and induced trends towards improved mobility and
executive function over a 2-week follow-up. The investigators thus contend that tDCS
targeting the left dlPFC holds promise to improve the control of standing and walking—and
ultimately reduce falls—in older adults. Still, the size and duration of tDCS-induced
benefits to older adult "fallers" have not been established. Moreover, to date, tDCS delivery
has attempted to optimize current flow based on a "typical" brain and has thus not accounted
for individual differences in skin, skull, cerebrospinal fluid and brain tissue in the aging
brain. Such personalization is now possible with the current flow modeling the investigators
propose.
The Overall Aim is to compare, in older adults with previous falls, the effects of a
personalized tDCS intervention designed to target the left dlPFC on the dual task costs to
standing and walking, and other physical and cognitive factors that are on the causal pathway
to falls and important to everyday function. The investigators will conduct a randomized,
sham-controlled, double-blinded trial with assessments at baseline and post-intervention
(immediate, 3-, 6-month follow-up) in 120 non-demented men and women (60 per arm) aged 65-85
years who report ≥2 non-syncopal falls within the previous year and are fearful of falling
again, yet have no major neural or musculoskeletal disorders that explain their falls. The
tDCS intervention will comprise 20, 20-minute sessions of tDCS over a 4-week period.
Importantly, the investigators will utilize current flow modeling from baseline structural
MRIs to determine the tDCS electrode placement and stimulation parameters that optimize
electrical current flow to the desired target within each participant's brain.
The investigators hypothesize that, in older adults with previous falls and over a 6-month
follow-up, a personalized tDCS intervention targeting the left dlPFC, as compared to sham,
will mitigate dual task costs to the control of standing and walking and enhance other
metrics of both physical and cognitive function.
cognitive decline. Most falls occur when standing or walking. Many activities require people
to stand or walk while performing tasks like talking or making decisions. Such "dual tasking"
interferes with the control of standing and walking. This interference, or "cost," is
exaggerated in older adults with previous falls and is predictive of future falls.
Neuroimaging evidence indicates that standing and walking,especially when dual tasking,
activate distributed brain networks including the left dorsolateral prefrontal cortex
(dlPFC)—a brain region sub-serving executive function. Thus, strategies that facilitate
activation of the left dlPFC and its connected neural networks hold promise to mitigate dual
task costs, improve physical and cognitive function, and ultimately, reduce falls.
Transcranial direct current stimulation (tDCS) provides a noninvasive means of selectively
modulating cortical excitability. The investigators have shown in younger and older adults
that a 20-minute session of tDCS designed to increase excitability of the left dlPFC reduces
dual task costs and improves mobility when tested just after stimulation. The investigators
have since completed a pilot, sham-controlled trial of a 2-week, 10-session tDCS intervention
targeting the left dlPFC in 20 older adults with slow gait and mild-to-moderate executive
dysfunction. The intervention was successfully double-blinded and well-attended. tDCS,
compared to sham, reduced dual task costs and induced trends towards improved mobility and
executive function over a 2-week follow-up. The investigators thus contend that tDCS
targeting the left dlPFC holds promise to improve the control of standing and walking—and
ultimately reduce falls—in older adults. Still, the size and duration of tDCS-induced
benefits to older adult "fallers" have not been established. Moreover, to date, tDCS delivery
has attempted to optimize current flow based on a "typical" brain and has thus not accounted
for individual differences in skin, skull, cerebrospinal fluid and brain tissue in the aging
brain. Such personalization is now possible with the current flow modeling the investigators
propose.
The Overall Aim is to compare, in older adults with previous falls, the effects of a
personalized tDCS intervention designed to target the left dlPFC on the dual task costs to
standing and walking, and other physical and cognitive factors that are on the causal pathway
to falls and important to everyday function. The investigators will conduct a randomized,
sham-controlled, double-blinded trial with assessments at baseline and post-intervention
(immediate, 3-, 6-month follow-up) in 120 non-demented men and women (60 per arm) aged 65-85
years who report ≥2 non-syncopal falls within the previous year and are fearful of falling
again, yet have no major neural or musculoskeletal disorders that explain their falls. The
tDCS intervention will comprise 20, 20-minute sessions of tDCS over a 4-week period.
Importantly, the investigators will utilize current flow modeling from baseline structural
MRIs to determine the tDCS electrode placement and stimulation parameters that optimize
electrical current flow to the desired target within each participant's brain.
The investigators hypothesize that, in older adults with previous falls and over a 6-month
follow-up, a personalized tDCS intervention targeting the left dlPFC, as compared to sham,
will mitigate dual task costs to the control of standing and walking and enhance other
metrics of both physical and cognitive function.
Inclusion Criteria:
- Men and women aged 65-85
- Self-report of two or more falls within the past year
- Self-report of fear of falling defined by a "yes" answer to the yes-or-no question "Is
the participant worried about falling in the future?"
- Trail Making Test (TMT) Part B time below 75th percentile of age-and education-based
norms
- A score of 9 or below on the Short Physical Performance Battery
Exclusion Criteria:
- Inability to stand or walk unassisted for 60 seconds
- Hospitalization within the past three months due to acute illness, or as the result of
a musculoskeletal injury significantly affecting gait or balance
- Any unstable medical condition
- a diagnosis of a gait disorder, Parkinson's disease, Alzheimer's disease or dementia,
multiple sclerosis, previous stroke or other neurodegenerative disorder
- Chronic vertigo
- Myocardial infarction within the past 6 months
- Active cancer for which chemo-/radiation therapy is being received
- Psychiatric co-morbidity including major depressive disorder, schizophrenia or
psychosis
- Chronic use of any sedating medications (sedatives, anti-psychotics, hypnotics,
anti-depressants) or change in medication within the previous month
- Legal blindness
- Contraindications to MRI or tDCS, including reported seizure within the past two
years, use of neuro-active drugs, the risk of metal objects anywhere in the body,
self-reported presence of specific implanted medical devices (e.g., deep brain
stimulator, medication infusion pump, cochlear implant, pacemaker, etc.), or the
presence of any active dermatological condition, such as eczema, on the scalp
- A score below 22 on the Telephone Interview of Cognitive Status (TICS)
- Mild or severe dementia defined by a Clinical Dementia Rating (CDR) score of one or
greater
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