Cutting back on certain foods could help reduce the risk of dementia, experts from Harvard Medical School say.

Foods with added sugars and high-glycemic-load carbohydrates, as well as fried foods, alcohol and nitrates can compromise our gut bacteria weakening our memory and focus.

Avoiding those foods can also help to fight inflammation and promote brain health.

Also, researchers say a new blood test could be a breakthrough in diagnosing mental health conditions.

A research team from the Indiana University School of Medicine says the test would help distinguish between mood disorders such as depression and bipolar disorder.

The team says the test would also allow patients to be matched with the right medications and avoid years of trials and error.