Sex link to multiple sclerosis

Multiple sclerosis (MS) might be triggered by a sexually transmitted infection, an expert has suggested.

However, the theory has been dismissed as pure speculation by other MS researchers.

The disease, which progressively attacks the nervous system, is commonly thought to be the result of a malfunctioning of the immune system.

Many doctors believe this is down to faulty genes.

Military barracks

But Dr Christopher Hawkes, of London's Institute of Neurology, believes the disease may be triggered by a sexually transmitted agent, and that young people, who are more prone to sexual experimentation, might be most at risk.

Dr Hawkes conducted an analysis of the known patterns of the disease, and examined clusters found in such places as the Faroe Islands, Iceland, the Orkneys and the Shetlands.

He found that an increase in rates of the disease was often associated with the barracking of military troops in the area.

Dr Hawkes also argued that a form of the disease known as primary progressive MS is very similar to another condition called tropical spastic paraplegia (TSP).

TSP is predominantly sexually transmitted and associated with a virus called retrovirus HTLV-1, which attacks the protective sheaths surrounding the nerves in a way similar to that found in MS.

Dr Hawkes said rates of MS are higher in young, sexually active people, and in cultures with more permissive attitudes to sex and higher rates of sexually transmitted infection.

He argued that differences in morality and culture offer an alternative explanation for the unequal distribution of MS around the world.

MS is rare in native populations isolated physically or culturally from white people, who tend towards a greater level of sexual promiscuity.

Support

A Danish study of over 12,000 MS cases appears to back Dr Hawkes' theory.

It found the prevalence of MS rose significantly around the time the contraceptive pill was introduced and barrier methods of contraception were used less frequently.

The female sex hormone oestrogen, found in the Pill, has been associated with a decreased risk of MS.

But a large US study indicated that risk of the disease doubled after six or more years of oral contraceptive use.

"This paper has little if any scientific value"

Professor Alastair Compston

Dr Hawkes does not suggest that MS is exclusively the result of a sexually transmitted infection.