Women who are neurotic in middle age may have an increased risk of developing Alzheimer's disease, a new study suggests.

A person with a neurotic personality may be described as moody, highly strung, a worrier and/or somebody who does not cope well with stress.

Dementia currently affects around 36 million people worldwide, including some 40,000 people in Ireland. Alzheimer's disease is the most common type of dementia, accounting for up to 80% of all cases.

Swedish researchers monitored 800 women over the course of almost four decades. When the study began in the late 1960s, all were middle-aged and each underwent a personality test, which included a measurement of their levels of neuroticism.

When the women were followed up in 2006, they were asked about any long periods of stress. They also underwent memory tests. By this stage, around one in five had developed some form of dementia.

"We could see that the women who developed Alzheimer's disease had more often been identified in the personality test 40 years earlier as having neurotic tendencies. We found a clear statistical correlation for the women who had at the same time been subject to a long period of stress," noted the researchers from the University of Gothenburg.

They said that while many factors can influence the risk of developing dementia, ‘our personality may determine behavior, lifestyle and how we react to stress, and in this way affect the risk of developing Alzheimer's disease'.

This marks the first Alzheimer study that has monitored participants from middle age to old age and according to the researchers, it displays the significant role that personality may have when it comes to the risk of developing Alzheimer's disease.

"Some studies have shown that long periods of stress can increase the risk of Alzheimer disease, and our main hypothesis is that it is the stress itself that is harmful. A person with neurotic tendencies is more sensitive to stress than other people," the Swedish team added.

Details of these findings are published in the journal, Neurology.

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