Aluminium is not used in the human body, although it is very common. People debate whether its use in deodorants and water treatment is healthy. Aluminium ions slow down plant growth in acidic soils. Aluminium may be a factor in Alzheimer's disease (a disease when the brain stops working and the patient is confused). But the Alzheimer's Society says overwhelming medical and scientific opinion is that studies have not convincingly demonstrated a causal relationship between aluminium and Alzheimer's disease.