## 4 Discussion
Recent studies suggest that this heterogeneity may be partially explained by the interplay of biomechanical, inflammatory, and neuroendocrine mechanisms, which modulate pain perception based on both the degree and distribution of excess body weight [45; 46]. Lifestyle is also related to pain. A SHARE-based analysis of 27,528 cases from 28 countries found that among lifestyle factors, physical inactivity had the strongest link to severe pain, more than poor sleep, smoking, or diet, highlighting its central role in both pain management and healthy aging [47]. Another study based on objective activity data suggests that short bouts of light-to-moderate physical activity (5 to 20 min) can help reduce pain intensity and its impact on daily life in older adults with chronic pain [48]. Another relevant aspect to consider is the participants' cognitive performance. Our findings showed poorer cognitive functioning among individuals with pain, a phenomenon that has also been previously described in the scientific literature. One study identified that persistent pain in older adults is associated with accelerated memory decline and increased risk of dementia [49]. Similarly, longitudinal studies have reported a more pronounced cognitive deterioration--particularly in memory, executive function, and orientation--among individuals with persistent pain trajectories [50]. Therefore, the co-occurrence of pain and cognitive impairment may represent a compounding factor contributing to the extent of independence loss in BADLs and IADLs [24]. However, these findings should be interpreted with caution due to the sociodemographic characteristics of the sample. Age has been consistently recognized as the primary non-modifiable risk factor for cognitive decline, both in the general population and in clinical groups. In this context, the age heterogeneity observed in our sample--particularly the overrepresentation of older participants in the WP group--may have influenced cognitive scores, potentially contributing to lower values in this subgroup. Our findings were statistically significant regarding perceived loneliness, long-term diseases, and mobility limitations. In summary, they indicate that individuals with WP exhibit a clinically complex functional profile, characterized by higher rates of depression, perceived loneliness, chronic conditions, mobility impairments, and physical inactivity compared to those with LP or no pain. This pattern aligns with the well-established concept of comorbidity, often observed in chronic WP, where physical, psychological, and social factors interact and mutually reinforce overall functional disability. The co-occurrence of depressive symptoms and pain may generate a bidirectional and synergistic relationship, in which emotional suffering amplifies pain sensitization processes, while persistent pain contributes to the development and maintenance of depressive symptomatology. This interactive model has been extensively supported in recent literature, highlighting the role of shared neurobiological mechanisms underlying both phenomena [51; 52; 53]. The number of ADL limitations in our results revealed a clear and progressive pattern in the association between pain and the extent of limitations in both BADLs and IADLs. Participants without pain exhibited virtually no limitations, while those with LP experienced a significant increase, and individuals with WP displayed the highest median limitations (1 in IADLs, up to 2 in BADLs), with all bivariate comparisons reaching statistical significance (\(p<0.001\)). These findings support the interpretation of a functional severity gradient, understood as a progressive decline in functional capacity associated with the magnitude and distribution of pain. This stepwise pattern is consistent with prior findings in large epidemiological studies showing a positive association between pain intensity or frequency and functional difficulty in older adults [38; 39; 54].