The overwhelming consensus of science is that ghosts do not exist. Their existence is impossible to falsify, and ghost hunting has been classified as pseudoscience.
Despite centuries of investigation, there is no scientific evidence that any location is inhabited by spirits of the dead Research has indicated that ghost sightings may be related to degenerative brain diseases such as Alzheimer’s disease.
Besides denoting the human spirit or soul, both of the living and the deceased, the Old English word is used as a synonym of Latin spiritus also in the meaning of “breath” or “blast” from the earliest attestations (9th century).
It could also denote any good or evil spirit, such as angels and demons; the Anglo-Saxon gospel refers to the demonic possession of Matthew 12:43 as se unclæna gast.
Historically, certain toxic and psychoactive plants, whose use has long been associated with necromancy and the underworld; have been shown to contain anticholinergic compounds that are pharmacologically linked to dementia (specifically DLB) as well as histological patterns of neurodegeneration. Older reports linked carbon monoxide poisoning to ghost-like hallucinations.