Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
Nuffield Department of Population Health, Big Data Institute, University of Oxford, Oxford, UK.
BMJ Ment Health. 2024 Oct 30;27(1):e301065. doi: 10.1136/bmjment-2024-301065.
Cannabis use during adolescence and young adulthood has been associated with brain harm, yet despite a rapid increase in cannabis use among older adults in the past decade, the impact on brain health in this population remains understudied.
To explore observational and genetic associations between cannabis use and brain structure and function.
We examined 3641 lifetime cannabis users (mean (SD) age 61.0 (7.1) years) and 12 255 controls (mean (SD) age 64.5 (7.5) years) from UK Biobank. Brain structure and functional connectivity were measured using multiple imaging-derived phenotypes. Associations with cannabis use were assessed using multiple linear regression controlling for potential confounds. Bidirectional two-sample Mendelian randomisation analyses were used to investigate potential causal relationships.
Cannabis use was associated with multiple measures of brain structure and function. Participants with a history of cannabis use had poorer white matter integrity, as assessed by lower fractional anisotropy and higher mean diffusivity in the genu of the corpus callosum, as well as weaker resting-state functional connectivity in brain regions underlying the default mode and central executive networks. Mendelian randomisation analyses found no support for causal relationships underlying associations between cannabis use and brain structure or function.
Associations between lifetime cannabis use and brain structure and function in later life are probably not causal in nature and might represent residual confounding.
Cannabis use is associated with differences in brain structure and function. Further research is needed to understand the mechanisms underlying these associations, which do not appear to be causal.
青春期和成年早期使用大麻与大脑损伤有关，尽管过去十年中老年人中大麻使用量迅速增加，但该人群的大脑健康影响仍研究不足。
探索大麻使用与大脑结构和功能之间的观察和遗传关联。
我们研究了来自英国生物库的 3641 名终生大麻使用者（平均（SD）年龄 61.0（7.1）岁）和 12255 名对照者（平均（SD）年龄 64.5（7.5）岁）。使用多种成像衍生表型测量大脑结构和功能连接。使用多元线性回归控制潜在混杂因素评估与大麻使用的关联。双向两样本孟德尔随机化分析用于研究潜在的因果关系。
大麻使用与大脑结构和功能的多项指标有关。有大麻使用史的参与者白质完整性较差，胼胝体膝部的各向异性分数较低，平均弥散度较高，默认模式和中央执行网络下的脑区静息状态功能连接较弱。孟德尔随机化分析未发现大麻使用与大脑结构或功能之间关联的因果关系有支持证据。
一生中使用大麻与晚年的大脑结构和功能之间的关联可能不是因果关系，而可能是残余混杂的结果。
大麻使用与大脑结构和功能的差异有关。需要进一步研究以了解这些关联的机制，这些关联似乎不是因果关系。
