DALLAS: A study has shown that the incidence of early onset dementia has risen markedly. Two decades ago, dementia largely occurred in those in their sixties. The “disproportionate increase” measured by scientists recently, indicates more frequent occurrences in Western countries, in those aged between 45 and 74, and with more risk to women. They warn of a “silent epidemic” and while there is no single factor identified for its cause, they believe pollution from aeroplanes and cars play a “major part”…