By Katherine Hobson

ADHD Diagnosis: New American Academy of Pediatrics treatment guidelines for attention deficit hyperactivity disorder say ADHD can be diagnosed in kids as early as age four, and that Ritalin and similar drugs are an appropriate treatment even for those youngest kids with persistent symptoms when behavioral-management strategies don’t work, the WSJ reports. many ADHD medications are only approved by the FDA for kids aged six and up, but physicians can use them off-label if they wish.

Birth Weight and Autism: in other pediatrics news, researchers report that low birth weight is linked to a higher risk of autism spectrum disorder later on, Health.com reports. five percent of babies born at less than 4 pounds, 7 ounces went on to develop an autism spectrum disorder by age 21, compared to about 1% of the overall population, Health.com says. The research, which appears in the journal Pediatrics, cannot say whether low birth weight actually causes autism.

Acquiring Anadys: Roche is buying Anadys Pharmaceuticals, which focuses on developing potential treatments for hepatitis C infection, for $230 million, the WSJ reports. The $3.70 per-share price for Anadys is 256% higher than its closing stock price on Friday.

Out of Antarctica: Renee-Nicole Douceur, the engineer who fell ill while working in the South Pole, has been successfully evacuated to New Zealand, ABC News reports. Douceur suffered symptoms of what may have been a stroke in late August, but a rescue was delayed because of weather conditions.