What is the fundamental first step in controlling indoor mold growth suspected of causing neurological symptoms?

Locating and fixing any leaks.

When mold is suspected as the root cause of chronic neurological symptoms like tingling, the immediate priority in environmental mitigation must be addressing the conditions that allow the mold to propagate. Mold requires moisture to survive and thrive indoors. Therefore, the fundamental and primary step involves a thorough investigation to locate and completely eliminate all sources of moisture intrusion. This includes fixing plumbing leaks, controlling excessive humidity levels through dehumidification, and ensuring robust ventilation. Until the moisture source is controlled and removed, any mold growth will likely persist or return, rendering subsequent cleaning efforts temporary and ineffective against the continuous toxic load.