Barbara Corcoran secretly cared for her mother with Alzheimer's for years. She was waiting for her own dementia risk before speaking out.

• Corcoran's mother, Florence, was diagnosed with Alzheimer's in her late 60s.
• Corcoran paid for all her care and shared hands-on caregiving with her nine siblings.
• Corcoran was terrified she had the disease until she saw a doctor earlier this year.

For the past 12 years, as Barbara Corcoran appeared on the television show "Shark Tank" and invested in more than 100 businesses, she lived with a secret fear: that she, like her mother Florence, would develop Alzheimer's disease.