Photobiomodulation as a therapeutic approach for attention-deficit/hyperactivity disorder in model rats

Current treatment options for attention-deficit/hyperactivity disorder (ADHD) primarily involve pharmacological and behavioral interventions; however, concerns regarding side effects, long-term safety, and limited efficacy in certain populations highlight the need for alternative therapies. This study evaluates the effectiveness of photobiomodulation therapy (PBMT) in mitigating core symptoms of ADHD-specifically impulsivity and hyperactivity-in a spontaneously hypertensive rat (SHR) model, by assessing neuroinflammation, preservation of neuronal integrity, and brain connectivity. SHRs, a well-established ADHD animal model, were used to assess PBMT's effects. The experimental design included three groups: a normal control group (WKY), an ADHD model group receiving PBMT (SHR-PBMT), and an ADHD model group receiving sham treatment (SHR-Sham group). PBMT was administered daily for 25 s at a wavelength of 808 nm over 21 consecutive days. Behavioral assessments (open field test), diffusion tensor imaging (DTI), and immunohistochemical analysis were conducted to evaluate neuroinflammation, neuronal integrity, and myelination. SHR-PBMT reduced total track length by 28.4% (p = 0.003) and average speed by 22.7% (p = 0.012) compared to the SHR-Sham group. Fractional anisotropy in the prefrontal cortex increased by 15% (p < 0.05) following SHR-PBMT compared to the SHR-Sham group. The density of Iba-1 positive cells decreased by 35% ± 5% (p = 0.004), indicating significant suppression of microglial activation. Additionally, compared with the SHR-Sham group, the SHR-PBMT group preserved myelin integrity in ADHD-related brain regions, suggesting neuroprotective effects. The findings suggest that PBMT is an effective nonpharmacological intervention for ADHD, reducing impulsivity and hyperactivity while preserving neuronal structure and function. By mitigating neuroinflammation and improving neuronal connectivity, PBMT presents a promising therapeutic alternative to conventional ADHD treatments. Further studies are needed to explore its clinical applicability and long-term safety in human populations.