Brain structure, psychosocial, and physical factors underpin back pain conditions; however, less is known about how these factors differ based on pain duration and location. We examined, cross-sectionally, 11,106 individuals from the UK Biobank who (1) were pain-free (n = 5616), (2) had acute back pain (n = 1746), (3) had chronic localised back pain (CBP; n = 1872), or (4) had chronic back pain and additional chronic pain sites (CWP; n = 1872). We found differences in structural brain measures in the chronic pain groups alone. Both CBP and CWP groups had lower primary somatosensory cortex {CBP mean difference (MD) (95% confidence interval [CI]): −250 (−393, −107) mm³, P < 0.001; CWP: −170 (−313, −27)mm³, P = 0.011} and higher caudate gray matter volumes (CBP: 127 [38,216]mm³, P = 0.001; CWP: 122 [33,210]mm³, P = 0.002) compared with pain-free controls. The CBP group also had a lower primary motor cortex volume (−215 [−382, −50]mm³, P = 0.005), whereas the CWP group had a lower amygdala gray matter volume (−27 [−52, −3]mm³, P = 0.021) compared with pain-free controls. Differences in gray matter volumes in some regions may be moderated by sex and body mass index. Psychosocial factors and body mass index differed between all groups and affected those with widespread pain the most (all, P < 0.001), whereas grip strength was only compromised in individuals with widespread pain (−1.0 [−1.4, −0.5] kg, P < 0.001) compared with pain-free controls. Longitudinal research is necessary to confirm these interactions to determine the process of pain development in relation to assessed variables and covariates. However, our results suggest that categorised pain duration and the number of pain sites warrant consideration when assessing markers of brain structure, psychosocial, and physical health.

大脑结构、心理社会和身体因素是背痛的基础；然而，人们对这些因素如何根据疼痛持续时间和部位而有所不同知之甚少。我们对来自英国生物银行的 11,106 名个体进行了横断面检查，他们 (1) 无疼痛 (n = 5616)，(2) 患有急性背痛 (n = 1746)，(3) 患有慢性局部背痛 (CBP) ；n = 1872），或（4）患有慢性背痛和其他慢性疼痛部位（CWP；n = 1872）。我们发现，仅慢性疼痛组的大脑结构测量存在差异。CBP和CWP组初级体感皮层均较低{CBP平均差（MD）（95%置信区间[CI]）：-250（-393，-107）mm ³，P < 0.001；CWP：−170 (−313，−27)mm ³，P = 0.011}和更高的尾状灰质体积（CBP：127 [38,216]mm ³，P = 0.001；CWP：122 [33,210]mm ³，P = 0.002 ）与无痛对照相比。CBP 组的初级运动皮层体积也较低（−215 [−382, -50]mm ³，P = 0.005），而 CWP 组的杏仁核灰质体积较低（−27 [−52, -3]） mm ³，P = 0.021）与无痛对照相比。某些区域灰质体积的差异可能会受到性别和体重指数的影响。所有组之间的心理社会因素和体重指数有所不同，对广泛疼痛的个体影响最大（全部，P < 0.001），而握力仅在广泛疼痛的个体中受到损害（−1.0 [−1.4, −0.5] kg，P < 0.001) 与无痛对照相比。有必要进行纵向研究来确认这些相互作用，以确定与评估变量和协变量相关的疼痛发展过程。然而，我们的结果表明，在评估大脑结构、心理社会和身体健康的标志物时，需要考虑分类的疼痛持续时间和疼痛部位的数量。