Passive smoking, also known as `second-hand' smoke, can cause neurological disease of dementia besides cardiovascular and respiratory diseases, according to the recent study conducted by the researchers from Anhui Medical University in China and King's College London, Press tv reported.

The result reveals that some 10 percent of the group involved in severe dementia which was associated with the exposure level as well as duration of passive smoking, according to the study published in Occupational and Environmental Medicine.

"Avoiding exposure to ETS (environmental tobacco smoke) may reduce the risk of severe dementia syndromes," said the study leader Dr Ruoling Chen, from King's College while emphasizing that "passive smoking should be considered an important risk factor for dementia syndromes."

"The increased risk of severe dementia syndromes in those exposed to passive smoking is similar to increased risk of coronary heart disease," Dr Chen added.

The World Health Organization (WHO) estimates that about 80 percent of over one billion smokers across the world live in low-and middle-income countries, where the burden of tobacco-related disease and death hits the highest rate.