Symptoms of depression that steadily increase over time in older age could indicate early signs of dementia, scientists have said. Other patterns of symptoms, such as chronic depression, appear not to be linked, a study published in The Lancet Psychiatry found.

Dutch researchers looked at different ways depression in older adults progressed over time and how this related to any risk. They concluded worsening depression may signal the condition is taking hold.

Dr M Arfan Ikram of the Erasmus University Medical Center in Rotterdam said depressive symptoms that gradually increase over time appear to be a better predictor of dementia later in life than other paths of depression.

The exact nature of depression on dementia risk remains unknown. They often occur together, but the Dutch study is among the first to look at different patterns of depression symptoms.

Depression varies greatly from one person to another. Some experience depressive symptoms only briefly, others have remitting and relapsing depression and some people are depressed all the time.