THE weekly trip to the hairdresser may feel therapeutic, but for elderly women it can present a health risk. Manipulation of the head and neck, especially if the neck is strained backwards over the sink, can alter the type of blood flow to the brain and may trigger a stroke, according to a US researcher.

Michael Weintraub, a neurologist at New York Medical College, says in New Scientist that the two major arteries which supply blood to the brain are particularly vulnerable to injury when the neck is manipulated. Conditions common in elderly people, such as arthritis and hardening of the arteries, exacerbate the risk and mean the neck should not be stretched excessively.