Is there a secret to living well into your 90s?

If there are secrets to living a longer and healthier life, Dr. Claudia Kawas is searching for them.

60 Minutes first met Dr. Kawas, a neurologist and professor at the University of California Irvine, in 2014 when Lesley Stahl interviewed her for a story titled "90+." 

Dr. Kawas and her team run a major study of aging California residents who began providing information about their diet, exercise, vitamins, and activities in 1981. 

"I really believe that when we learn things from the 90-year-olds, they're going to be helping the 60 and 70-year-olds, not just how to become 90-year-olds, but how to do it with style and as good a function as possible," Dr. Kawas told 60 Minutes in 2014. 

The multi-million dollar study, funded by the National Institutes of Health, discovered several factors that were associated with longer life. The study found moderate alcohol consumption of up to two drinks a day led to a 10% to 15% reduced risk of death compared to non-drinkers. It also revealed a caffeine intake equivalent to one to three cups of coffee a day was better than more, or none. 

Sid Shero was 92 when Stahl last interviewed him. Scans of Shero's brain revealed the presence of amyloid plaques, the physical markers of Alzheimer's disease, but the World War II veteran was cognitively unaffected and our 60 Minutes team even found him driving around in a convertible.

This summer, Shero turned 99, and Stahl interviewed him once again, along with the other living participants from the original story.

The follow-up report airs this Sunday on 60 Minutes.