TRANSCRANIAL INFRARED LASER STIMULATION IMPROVES COGNITIVE PERFORMANCE AND INDUCES A BIPHASIC CEREBRAL PERFUSION RESPONSE IN REMITTED BIPOLAR DISORDER

Transcranial infrared laser stimulation (TILS) is a novel non-invasive neuromodulation approach under investigation for cognitive enhancement in bipolar disorder (BD). We evaluated the acute and cumulative effects of repeated TILS on neurocognitive performance and cerebral blood flow (CBF) in individuals with remitted BD. In an open-label pilot study, 28 participants with remitted BD received weekly 10-minute TILS sessions (wavelength 1064 nm, power density 250 mW/cm2) over the bilateral prefrontal cortex for 6 weeks. Neurocognitive outcomes were assessed before and after treatment using the Cambridge Neuropsychological Test Automated Battery (CANTAB), focusing on executive and attentional domains. CBF was measured via arterial spin labeling (ASL) MRI at baseline, after the first TILS session (acute effect), and following the final session (cumulative effect). Repeated-measures ANOVAs and MANOVAs evaluated changes over time, with follow-up nonparametric tests for significant multivariate effects. TILS was associated with significant improvements in cognition: participants showed faster response inhibition (p = 0.036), improved sustained attention (p = 0.002), and greater cognitive flexibility (p = 0.012) after the six-week intervention. Neuroimaging resultsrevealed a biphasic CBF response, with acute TILS inducing increased perfusion and cumulative TILS leading to decreased perfusion across key regions implicated in BD pathophysiology, including the prefrontal cortex, amygdala, and ventral striatum. These findings demonstrate that repeated TILS can enhance executive function and attentional control while modulating cerebral hemodynamics in remitted BD, highlighting a promising neuromodulation strategy to address persistent cognitive deficits in this population.

References

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