In addition to providing rapid alleviation of neurologic symptoms and enhanced intracranial disease control, WBRT might also prolong the time to develop neurocognitive function (NCF) decline. However, paradoxically NCF decline can also occur due to a sequel of WBRT. In terms of the time course of WBRT-induced NCF decline, it might vary considerably according to the specific domains which are selected to be measured. Early neurocognitive decline occurs within the first 1 - 4 months after WBRT for brain metastases. The domains of early neurocognitive decline principally involve verbal and short-term memory recall.