The general public has a limited understanding of dementia and the most common misconception about the illness is that it is a normal part of aging, a new Irish study has found.

Researchers from Trinity College Dublin (TCD) and St James's Hospital's Dementia Services Centre carried out a detailed analysis of 40 research articles on dementia from 15 different countries that had been published over the last 20 years.

They found that members of the public had a limited understanding of dementia and Alzheimer's disease.

Dementia describes the gradual deterioration of a person's mental abilities, in combination with changes in personality and behaviour. The main symptoms include memory loss, disorientation, communication difficulties, personality changes, such as moodiness and bad temper, and a gradual decline in a person's ability to undertake ordinary, everyday activities.

Around 48,000 people in Ireland have dementia, the most common type of which is Alzheimer's.

The study revealed that the most common misconception surrounding dementia is that it is a normal part of aging, and many people were unclear about when normal age-related memory loss becomes severe enough to suggest dementia.

In fact, almost half of the studies reviewed revealed very limited knowledge of the illness. For example, one large study from Israel carried out in 2006 found that two in three people thought that dementia was a normal part of aging.

Meanwhile, a study carried out only last year in France found that three in four people believed it was normal to lose your memory as you age and most could not recognise the early signs of dementia.

An Irish study carried out in 2012 found that 42% of people aged 65 and older thought that dementia was normal in older people.

The researchers also found poor understanding about modifiable risk factors, with many people incorrectly believing they have absolutely no control over whether they develop dementia or not.

While a lot of people appeared to know that there are genetic risk factors related to dementia, knowledge about modifiable risk factors, such as smoking, high blood pressure and high cholesterol was poor.

For example, a study in the UK in 2012 found that only one in four people were aware that high cholesterol and high blood pressure can increase a person's risk of developing the condition. A study in France in the same year found that just one in three people knew smoking was a risk factor.

"Lack of public understanding of dementia has negative consequences for both the individual coping with the symptoms and for family caregivers. The individual may experience stigma, embarrassment and ridicule due to negative societal attitudes and retreat from activities once enjoyed and the caregiver may experience social isolation since neighbours, friends and family gradually withdraw, not knowing how to behave," commented Suzanne Cahill, Associate Professor of Social Work and Aging at the School of Social Work and Social Policy at TCD.

She said that the findings suggest that health promotion and prevention policies need to be developed ‘for all stages of life'.

Details of these findings are published in the journal, Alzheimer's Disease and Associated Disorders.

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