BACKGROUND Radiation therapy (RT) to the brain may result in cognitive impairment. The primary objective of the present study was to examine the relationship between RT dose to the hippocampus and learning and memory functions. Secondary objective was to examine relationships between doses to other brain structures and specific cognitive functions. METHODS A cross-sectional analysis was undertaken in 78 primary brain tumour patients after RT. Cognitive function was assessed by neuropsychological tests. Test scores were standardized using normative data adjusted for age and level of education. Test-specific cognitive impairment was determined as a z-score ≤-1.5. Radiation dose to brain structures and test-specific cognitive impairment outcomes were fitted to a logistic regression model. RESULTS High RT dose to the left hippocampus was associated with impaired verbal learning and memory (p = 0.04). RT dose to the left hippocampus, left temporal lobe, left frontal lobe and total frontal lobe were associated with verbal fluency impairment (p < 0.05) and doses to the thalamus and the left frontal lobe with impaired executive functioning (p ≤ 0.03). Finally, RT dose to the brain and thalamus were associated with impaired processing speed (p ≤ 0.05). CONCLUSION The present study indicates that the hippocampus may be vulnerable to radiation and that high radiation doses to the left hippocampus may lead to significant verbal learning and memory impairment. High RT doses to the left hippocampus and other left side structures may result in impairments in verbal fluency, executive function, and processing speed. Validation of these findings are being undertaken in a prospective study.

中文翻译：

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对患有原发性脑肿瘤的成年人的海马和其他脑结构进行辐射后的认知障碍

背景对大脑的放射治疗（RT）可能导致认知障碍。本研究的主要目的是检查海马体的放疗剂量与学习和记忆功能之间的关系。次要目标是检查其他大脑结构的剂量与特定认知功能之间的关系。方法对 78 名接受放疗后的原发性脑肿瘤患者进行横断面分析。通过神经心理学测试评估认知功能。使用根据年龄和教育水平调整的规范数据对测试分数进行标准化。测试特定的认知障碍被确定为 z 分数≤-1.5。大脑结构的辐射剂量和测试特定的认知障碍结果适合逻辑回归模型。结果 左海马体的高 RT 剂量与语言学习和记忆受损有关 (p = 0.04)。左海马、左颞叶、左额叶和总额叶的 RT 剂量与语言流畅性障碍 (p < 0.05) 和丘脑和左额叶的剂量与执行功能受损 (p ≤ 0.03) 相关。最后，大脑和丘脑的 RT 剂量与处理速度受损有关 (p ≤ 0.05)。结论 本研究表明，海马体可能容易受到辐射的影响，左侧海马体的高辐射剂量可能会导致显着的语言学习和记忆障碍。对左侧海马体和其他左侧结构的高剂量 RT 可能会导致语言流畅性、执行功能和处理速度受损。