I would consider the following:
1. Give Arterosil to address potential CNS microvascular issues.
2. Downregulate CNS inflammation by
a) address all sources of systemic inflammation,
b) consider giving Lion’s Mane mushroom, with the goal of raising levels of nerve growth factor (NGF), which is a known “OFF” signal in neuron-microglial interactions (if you’re not familiar with Neuron-Microglial interactions, google “Yanuck Frontiers in Psychiatry neuron microglial” and you’ll find an open source paper on the topic.
3. Bring histamine levels down. Molybdenum may be particularly important there, in addition to the usual. Luteolin may be particularly important, in addition to quercetin and rutin.
4. Glutathione and NAC.
5. He needs to get labs for the usual targets (he should be working with a practitioner).
6. Whatever else the case dictates.

He should work with a practitioner to address this properly.