Physical inactivity among adults is a major contributor to the escalating global burden of neurodegenerative diseases and mental disorders. The "Weekend Warrior" (WW) pattern-characterized by condensing the recommended volume of physical activity (PA) into one or two days-has emerged as a potential strategy for time-constrained adults. However, a systematic synthesis comparing the potential association of the WW pattern on neuropsychological outcomes (e.g., neurodegenerative diseases, mental health conditions and cognitive function) with those of inactive (IA) and regular exercise (RE) patterns remains limited. This systematic review aimed to assess the associations of the WW pattern with neurodegenerative diseases (e.g., dementia, Parkinson's disease), mental health conditions (e.g., depression, anxiety, psychological distress), and cognitive function (CF), and to compare these neuropsychological outcomes with those associated with IA and RE patterns. A systematic search of PubMed, Web of Science, ScienceDirect, and Chinese databases (CNKI, Wanfang) was conducted for observational studies published from inception to October 2025. Thirteen studies (5 cohort and 8 cross-sectional studies) involving adults were included. The assessment of methodological quality was conducted using the Agency for Healthcare Research and Quality (AHRQ) methodology and the Newcastle-Ottawa Scale (NOS). The majority of included studies indicated that the WW pattern was inversely associated with the risks of neurodegenerative diseases and mental health conditions and enhanced CF, exhibiting associations of a similar magnitude to those of RE. Furthermore, the synthesis highlighted prevailing gaps in the extant literature, particularly regarding the lack of randomized controlled trials, insufficient control for confounding variables such as social context, and the limited investigation into the neurobiological mechanisms underlying these associations. This systematic review emphasizes the WW pattern as a viable and time-efficient strategy that promotes positive neuropsychological outcomes, exhibiting associations of a similar magnitude to those observed with RE. The findings substantiate the flexibility inherent in PA guidelines, underscoring that adhering to recommended PA volumes is highly beneficial, even when accumulated within a condensed timeframe. Future research should prioritize randomized controlled trials and investigations into neurobiological mechanisms to further validate causal relationships and elucidate the underlying mechanisms driving these associations.