I watched my sister DISAPPEAR

Gerri Gallagher still lives with the pain of losing her sister Constance to a cruel and formidable disease

Back in February, the news that Bruce Willis had been diagnosed with frontotemporal dementia (FTD) hit me hard. Not because I'm a huge Die Hard fan, but because I know far too much about FTD, and my heart breaks for the 68-year-old Hollywood actor and his family. Last April, my sister Constance lost her eight-year battle with one of the FTD diseases. She was 58 years old.

Six years ago Constance was diagnosed with primary progressive aphasia (PPA), a form of FTD. It's a rare neurodegenerative disease that begins as a subtle language disorder and progresses to a near-total inability to speak, read, write or understand what is heard. What causes PPA is unclear, but it attacks the frontal and temporal lobes of the brain that control personality, behaviour and speech. It's always fatal.

We Gallaghers were a formidable brood seven siblings from American-Irish Catholic parents. Our childhoods were spent on a 25-acre estate that was 60 miles north-west of Manhattan, with horses, dogs, cats and chickens. I was seven when Constance was born. Finally, I had the sister I'd longed for, rather than a fourth brother (although, in time, I was blessed with another brother and sister). I dressed her up; I spoilt her; I protected her.

When I moved to the UK after my wedding in 1986, that ev no one cried more than Constance. Between my quarterly visits to the States we spoke regularly and stayed close, regardless of the distance. She often talked of her longing to live my life to be married and have a career as a magazine editor. I reassured her that everything would fall into place in time, and she would be happy. I remember glibly saying, 'Good things come to those who wait.' How wrong I was.