Veterans aged 50 and above who have suffered mild traumatic brain injury (mTBI) are twice as prone to develop dementia. From 2001, during the Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) campaigns, over 470,000 veterans were diagnosed with TBI. Beyond the prevalence of the signature wound of the OEF and OIF campaigns, the number of mTBI cases within the VA system is believed to be much higher. Disturbingly, an increasing number of veterans, especially those with TBI, are being diagnosed with mild cognitive impairment and frank dementia between ages 50-60. With 72% of veterans (13.2 million, a figure rising yearly) over 50 years old (Vetpop, 2020), the VA needs to implement preventative and rehabilitative interventions to limit the growing impact of cognitive decline in the veteran population.
Cognitive training paradigms have been developed and tested over the past decades, with some controversy over the overall effect10. Programs such as repeated task practice (e.g., list memorization and mnemonics) have shown mixed results in aggregate, primarily due to a lack of training transfer across domains. In contrast, process-based cognitive training has consistently improved general cognitive ability with one program, visual attention training, showing considerable transfer effects. Also known as speed-of-processing training (cf. - useful field-of-view \[UFOV\]), visual attention training is done on a computer and targets perceptual deficits associated with aging and TBI.
Changes in brain function that reduce the ability for perceptual information to be processed are likely mechanisms of impaired cognition. Visual attention training was developed to increase visual perception directly to counteract deficient visual fields. Previous studies have shown that visual attention training increases instrumental daily activities pertinent to driving performance, resulting in prolonged driving mobility. Unfortunately, visual attention training paradigms have required an extended training duration (months) and tend to show varied outcomes. The identified cognitive mechanism of increased perceptual detail processing is quite powerful, but individual training response may depend on one's ability to apply selective cortical inhibition. Cortical oscillations measured with electroencephalography (EEG) are believed to reflect such inhibition. Recent EEG work during visual attention training has shown that people exhibiting selective engagement of alpha patterns have faster processing speed and better perceptual discrimination.
Our recent VA-funded projects in aging have shown that procedural motor learning performance is related to individual differences in excitatory/inhibitory (E/I balance) assessed with transcranial magnetic stimulation (TMS) (Novak et al., under review). Moreover, recent work has also shown that neurological changes in cortical activity are evident after just 10 hours of visual attention training. The current project will evaluate changes in EEG measures of cortical inhibition in older veterans to improve perceptual processing using an adapted visual attention training program. The present work expands on prior work in neuromodulation using low-cost, nonpharmacological rehabilitation techniques.
