Neurocognitive functions decline after paediatric brain tumour radiotherapy

While children with brain tumours already suffer from impaired neurocognitive functions, radiotherapy appears to worsen these impairments, a new study has found.

Researchers enrolled 50 paediatric brain tumour survivors who had undergone radiotherapy ≥5 years prior to enrolment. Neurocognitive assessments were conducted before and after radiotherapy using various tests, the most common of which were IQ tests as delivered by different versions of the Wechsler scale.

Even before radiotherapy, neurocognitive function was already compromised among participants. Before surgery, 60 percent of patients were already performing ≥1-standard deviation (SD) below the normative mean on at least one IQ measurement; after surgery, this proportion rose to 64 percent.

These findings were even more pronounced when accounting for more comprehensive neurocognitive indices as compared with IQ scores alone. Before and after surgery, 78 percent of patients performed ≥1-SD below the normative mean.

Common neurocognitive difficulties included fatigue, learning, attention, memory, and processing speed.

Neurocognitive impairment worsened after radiotherapy. Accounting for more comprehensive assessments, 80 percent of patients performed ≥1-SD below the normative mean 0–2.99 years after radiotherapy. This percentage jumped to 91 percent and 95 percent at 3–4.99 and 5 years after radiotherapy, respectively.

“We found that neurocognitive functions were affected before radiotherapy and that these effects were more pronounced over time, particularly for working memory and processing speed,” the researchers said.

“Our study illustrates the importance of structured neuropsychological assessment before and after radiotherapy; the timing of the assessment is important, and confounding risk factors need to be identified to better evaluate treatment protocols,” they added.