Sex-dependent effects of ultra-low-dose-THC preventive treatment on neuroinflammation and cognitive decline in 5xFAD mice

Background: Alzheimer’s disease (AD) remains the most prevalent cause of dementia, yet no existing treatment effectively prevents its onset. Current therapies primarily aim to slow disease progression or manage symptoms, leaving a critical gap in preventive strategies. Recent findings suggest that ultra-low-dose tetrahydrocannabinol (ULD-THC) may exert neuroprotective effects without the adverse consequences associated with chronic THC use. This study investigates whether preventive ULD-THC treatment can mitigate neuroinflammation and early cognitive decline in the 5xFAD mouse model of AD, with a specific focus on sex differences in treatment response. Methods: Male and female 5xFAD mice received monthly ULD-THC injections from 3 to 5 months of age, before significant pathology emerged. At 6 months, behavioral assessments were conducted, followed by molecular analyses of hippocampal and prefrontal cortex (PFC) tissue. Results: Results indicated that ULD-THC attuned AD-related cognitive decline in both males and females, with sex-specific neuroinflammatory responses. Males exhibited reduced hippocampal inflammation, whereas females showed reduced inflammation in the PFC, suggesting distinct neuroprotective mechanisms across sexes. Conclusions: These findings highlight ULD-THC’s potential as a preventive strategy for AD, emphasizing the importance of sex-dependent therapeutic approaches. By attenuating neuroinflammatory processes before cognitive deficits fully manifest, ULD-THC offers a novel, biologically targeted approach to AD prevention. Future research should explore its long-term efficacy and translational potential in clinical settings.