Prefrontal Theta Burst Stimulation to Improve Cognitive Impairment After ICU Delirium

Prefrontal Theta Burst Stimulation to Improve Cognitive Impairment After ICU Delirium: A Randomized Sham-Controlled Pilot Trial

Many older adults who survive a stay in the intensive care unit (ICU) experience delirium, a sudden change in attention and awareness caused by serious illness. Although delirium may resolve before hospital discharge, many survivors continue to experience ongoing problems with memory, attention, processing speed, and executive function (such as planning, organizing, and multitasking). These cognitive difficulties can interfere with daily activities and may increase long-term risk for cognitive decline. Currently, there are no proven treatments specifically designed to improve thinking and attention after ICU delirium.

This study is testing whether a noninvasive form of brain stimulation called intermittent theta burst stimulation (iTBS) is safe, feasible, and potentially helpful for improving cognitive function in older ICU survivors who previously experienced delirium. iTBS is a patterned form of transcranial magnetic stimulation (TMS). It involves placing a magnetic coil gently against the scalp to deliver brief pulses of magnetic energy to a targeted region of the brain. In this study, stimulation is directed at the left dorsolateral prefrontal cortex, an area involved in attention, executive function, and cognitive control. The device used in this study is cleared by the U.S. Food and Drug Administration (FDA) for other conditions (such as depression), but its use for post-delirium cognitive impairment is investigational.

This is a randomized, double-blind, sham-controlled pilot trial. Up to 40 community-dwelling adults between the ages of 50 and 75 who are approximately three months after an ICU stay with documented delirium will participate. Individuals with known dementia or certain neurological or psychiatric conditions are excluded to ensure safety and interpretability of results.

Participation lasts approximately six weeks and includes 11 total visits: a baseline visit, 10 stimulation sessions over two weeks (five sessions per week), and a one-month follow-up visit. Each stimulation session lasts about 15-20 minutes. Cognitive testing is performed at baseline, immediately after the two-week stimulation period, and again one month later. The primary outcome measure is change in executive function, assessed using the Trail Making Test Part B. Additional tests measure attention, processing speed, language, and memory.

The primary goals of this pilot study are to evaluate feasibility (ability to recruit and retain participants), safety, and tolerability of the stimulation protocol, and to estimate the magnitude of any cognitive changes. This study is not designed to establish definitive clinical effectiveness but to generate data to inform larger future trials. The broader goal of this research is to explore whether prefrontal neuromodulation could become a future strategy to promote cognitive recovery after ICU delirium.

Inclusion Criteria:

• Eligible individuals must have experienced an ICU admission with documented delirium (confirmed via documented Confusion Assessment Method for the ICU score12 [CAM-ICU] or Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition13(p5) [DSM-5] criteria)
• Age 50 to 75 years old
• 3 months post-ICU discharge at time of enrollment (defined as within 90 ± 14 days)
• English fluency
• Family or close friend for collateral
• Community-dwelling status
• Montreal Cognitive Assessment14 score between 18 and 25.

Exclusion Criteria:

• Diagnosis of mild cognitive impairment or dementia (prior to delirium episode)
• Seizure disorder
• Other significant neurologic disease (e.g., Parkinson's, Huntington's, Normal pressure hydrocephalus, tumor, progressive supranuclear palsy, multiple sclerosis, hematomas, traumatic or anoxic brain injury)
• Structural CT/MRI with evidence of infection or other clinically significant focal lesions (cortical strokes not large enough to distort anatomy and/or multiple lacunar infarctions ≤ 1.5cm and/or extensive white matter disease are allowed)
• Unstable or decompensated cardiac disease (e.g., <3 months myocardial infarction, unstable angina, decompensated congestive heart failure NYHA class 3-4)
• Pacemaker
• Cochlear implants
• Implanted medication pumps
• Intracranial metal implants
• Previous TMS treatment
• Pregnancy (negative urine or serum b-HCG or history of prior surgical sterilization or post-menopausal status [12 months or more of amenorrhea])
• Current depressive disorder (Beck Depression Inventory score15 <13)
• History of suicide attempts
• Schizophrenia
• Bipolar disorder
• Alcohol or substance abuse
• Severe visual/hearing impairment.
• Informant Questionnaire on Cognitive Decline in the Elderly16 (IQCODE) score ≥3.4 (suggesting prior cognitive decline)