How common are the "common" neurological disorders?

Neurological disorders such as multiple sclerosis and Alzheimer's disease are becoming more common according to a recent large analysis.Dr Deborah Hirtz (the National Institute of Neurological Disorders and Stroke, Bethesda) and colleagues comment that accurate estimates of the numbers of people affected by neurological disorders are needed to plan research on causes, treatment and preventative measures.To explore this further the group recently reviewed approximately 500 articles, published between 1990 and 2005, describing the prevalence of 12 conditions commonly managed by neurologists.From their analysis Hirtz's group report the prevalence of multiple sclerosis (MS) to be nearly 1 in 1000, a figure that is 50% higher than earlier estimates. "Whether this reflects improvements in diagnosis or whether the incidence is actually increasing deserves further study," the authors note.The researchers also identify a "substantial increase" in the prevalence of Alzheimer's disease, affecting 67 out of every 1000 people aged 65 or older. This, they attribute, at least in part, to the growing proportion of very elderly people.Other highlights from the study include:Nearly six out of every 1000 children have some form of autism;...