Early symptoms of dementia can be subtle and vague and may not be immediately apparent. Unfortunately, when they are clear, it is often too late.

Dementia refers to a group of symptoms associated with deterioration of the brain. The most common cause of dementia is Alzheimer’s disease, a brain disorder that slowly destroys memory and thinking skills. One study looked at certain habits in middle age and how they might increase the condition’s early onset.

A study led by Dr Severin Sabia, from Inserm College and University College London, looked at how sleep patterns early in life might affect the onset of dementia decades later.

The study was supported in part by the National Institute on Aging of the National Institutes of Health (NIA) and appeared in Nature Communications.

The researchers examined data on nearly 8,000 people in the United Kingdom starting at the age of 50.

Participants were assessed on a variety of measures, including being asked on six occasions between 1985 and 2016 how many hours they slept at night.

To assess the accuracy of this self-report, some participants wore accelerometers to objectively measure sleep time.

During the study period, 521 participants had dementia, with an average age of 77.

The results of the study showed that people in their fifties and sixties who slept six hours or less were more likely to develop dementia later in life.

Compared with those who got a normal sleep (defined as seven hours), people who got less rest each night were 30% more likely to develop dementia.

Other studies have suggested that sleep patterns early in life may contribute to the risk of developing dementia later on.

Inadequate sleep and sleeping longer than average were both linked to an increased risk of dementia.

However, it has been difficult to determine whether these sleep changes contribute to the disease or simply reflect early symptoms.

“Many of the treatments that have been suggested to improve sleep quality include lifestyle changes,” the Alzheimer’s Association said.

The health charity added: ‘Regular sleep regimes, eating schedules, diets and exercise and ensuring exposure to bright light in the morning are all that can improve the quality of your sleep. However, further research is needed to indicate whether these activities have effect on the risk of dementia or disease progression.

Early symptoms of dementia include:

• Memory problems, especially remembering recent events.

• Low focus.

• Changes in personality or behaviour.

• Apathy, withdrawal or depression.

• Loss of ability to carry out daily tasks.