Why male suicide rates are lowest for 30 years

Reduced access to poisonous car exhaust fumes is one of the reasons why suicide rates in young men are at their lowest levels since the 1970s according to an editorial in the BMJ.

The magazine considers two recent studies by researchers from the University of Bristol carried out in collaboration with the Office for National Statistics and IMS Health.

The first was a time trend analysis among men and women aged 15-24 and 25-34 between 1968 and 2005 using data on suicide mortality, population statistics and surveys, prescribing information and data on unemployment and divorce.

They found that for 15-24 year-old men, the overall suicide rate dropped from 16.6 per 100,000 people in 1990 to 8.5 per 100,000 in 2005. Amongst 25-34 year old men, overall suicide rates declined from 22.2 per 100,000 in 1990 to 15.7 per 100,000 in 2005.

Car exhaust emission legislation in 1993 has led to a marked reduction in car exhaust gas poisoning due to the increased number of cars with catalytic converters. But another factor is the impact of the suicide prevention policy initiatives in England and Wales, the BMJ believe.

For women, suicide rates in the 21st century are at their lowest levels since 1968, but the proportion of women aged 15-34 committing suicide by hanging has increased massively from 5.7 per cent of all suicides to 47.3 per cent by 2005.

Professor David Gunnell, co-author of the papers, said: "Favourable changes in several different factors - levels of employment, substance misuse and antidepressant prescribing as well as policy focus on suicide and vehicle exhaust gas legislation - may have contributed to the recent reductions."

The second study finds no effect on suicide of the recent restrictions on antidepressant prescribing to children and adolescents in the UK.

They analysed three separate sets of data between 1993 and 2006 (SSRI antidepressant prescriptions to 12-19 year olds in the UK, annual deaths from suicide in 12-17 year olds in England and Wales, and hospital admissions for self-harm in 12-17 year olds in England).

But they found no evidence of a temporal association between trends in antidepressant prescribing and deaths from suicide or hospital admissions for self harm despite a halving in levels of prescribing following regulatory action in 2003.

The authors say: "These findings are important because they suggest that reduced access to antidepressants in young people appears not to have had an adverse impact on suicide deaths."