Middle-aged adults who have lung disease may be at a greater risk of developing dementia or cognitive impairment later in life, according to a new research.The study found that both restrictive and obstructive lung diseases were associated with dementia, including Alzheimer's disease, and with mild cognitive impairment.However, the link was stronger for restrictive lung diseases such as idiopathic pulmonary fibrosis and sarcoidosis than it was for chronic obstructive pulmonary disease (COPD).The reason could be because lung disease produced low blood oxygen levels, which in turn may have led to inflammation, stress and damage to the brain's blood vessels, the researchers noted."Preventing dementia is a public health priority, and previous studies have suggested that poor lung health, which is often preventable, may be linked to a greater risk of developing dementia," said Pamela L. Lutsey, lead researcher at the University of Minnesota in the US.For the study, the researchers included more than 14,000 participants with an average age of 54, among which 1,407 instances of dementia were reported.Findings, published in the American Journal of Respiratory and Critical Care Medicine, showed that the odds of dementia were 58 per cent higher among those with restrictive lung disease compared to those without lung disease.Also, dementia was 33 per cent higher among those with obstructive lung disease.