A Dutch woman who was the oldest person in the world when she died aged 115 appeared sharp right up to the end, joking that pickled herring was the secret to her longevity.

Scientists say that Henrikje van Andel-Schipper's mind was probably as good as it seemed. A post-mortem analysis of her brain revealed few signs of Alzheimer's or other diseases commonly associated with a decline in mental ability in old age.

Professor Gert Holstege of Groningen University said: "Everybody was thinking that when you have a brain over 100 years, you have a lot of problems."