Swimming Toward Recovery: Early Aquatic Therapy as a Bridge to Delayed Environmental Enrichment After Experimental Traumatic Brain Injury

Environmental enrichment (EE) is a well-established preclinical model of neurorehabilitation after traumatic brain injury (TBI). However, most paradigms initiate EE immediately after injury and provide it continuously, unlike clinical rehabilitation, which is typically delayed until medical stabilization and delivered for defined periods. We hypothesized that early aquatic therapy (AQT), an exercise-based intervention, would enhance the benefits of delayed EE, providing a rehabilitative bridge during the early post-injury period. Adult male rats received a cortical impact or sham injury and were housed under standard (STD) conditions. Beginning 1 day after surgery, bridge groups received daily AQT for 7 days, while comparison groups remained in STD housing. On post-injury day 8, EE (6 h/day) was initiated in bridge and EE-only groups. Motor, cognitive, and anxiety-like behaviors were assessed. AQT alone and AQT + EE improved motor performance versus STD (p < 0.05), with AQT + EE producing the fewest foot slips and outperforming EE alone. EE improved spatial learning, while AQT + EE produced the strongest acquisition among TBI groups (p < 0.05); memory retention improved only in EE-treated groups. AQT + EE outperformed STD on the first and third reversal stages of executive function, whereas EE alone outperformed STD on the third reversal. Reduced anxiety-like behavior occurred only in EE-treated groups. Overall, the hypothesis was partially supported as sequential AQT + EE produced greater improvements than EE alone on selected motor, spatial learning, and executive outcomes, but EE alone improved memory retention and anxiety-like behavior. These findings support early AQT as a rehabilitative bridge to delayed EE and warrant further investigation of staged rehabilitation paradigms after TBI.