Alcohol misuse, coming from a lower socioeconomic background, loneliness and having a hearing impairment are among 15 factors found to significantly increase the risk of early-onset dementia, according to a “groundbreaking” study. Almost 4 million people worldwide experience dementia symptoms before they are 65, with 370,000 people newly diagnosed each year. While previous research has found that lifestyle changes can cut the risk of dementia among older people, the authors of the new study said this was the first finding that suggested the risk of early-onset dementia could be reduced in the same way. The study looked at 350,000 under-65s who were part of the UK Biobank study. Researchers from the universities of Exeter and Maastricht examined what could affect a person’s predisposition to early-onset dementia, including genetic, lifestyle and environmental factors. They found 15 factors that significantly increased the risk, including a lower formal education or lower socioeconomic status, health factors such as vitamin D deficiency, hearing impairment and depression, and lifestyle factors such as alcoholism and social isolation. “Our study identified 15 lifestyle and health-related factors that were associated with young onset dementia incidence,” the researchers said. “While further exploration of these risk factors is necessary to identify potential underlying mechanisms, addressing these modifiable factors may prove effective in mitigating the risk of developing young onset dementia and can be readily integrated in current dementia prevention initiatives.” Dementia is one of the biggest illnesses facing UK health infrastructure, and a study last month suggests that 1.7 million people in the UK could have the condition by 2040. In Britain, about 900,000 people are living with dementia, while more than 70,800 are living with early-onset dementia. Sebastian Köhler, a professor of neuroepidemiology at Maastricht University and one of the lead authors of the research, said: “We already knew from research on people who develop dementia at older age that there are a series of modifiable risk factors. “In addition to physical factors, mental health also plays an important role, including avoiding chronic stress, loneliness and depression. The fact that this is also evident in young-onset dementia came as a surprise to me, and it may offer opportunities to reduce risk in this group too.” Dr Janice Ranson, a senior research fellow at the University of Exeter, said that the research “breaks new ground in identifying that the risk of young-onset dementia can be reduced”. She added: “We think this could herald a new era in interventions to reduce new cases of this condition.” Dr Leah Mursaleen, the head of clinical research at Alzheimer’s Research UK, which co-funded the study, said: “We’re witnessing a transformation in understanding of dementia risk and, potentially, how to reduce it on an individual and societal level. “In recent years, there’s been a growing consensus that dementia is linked to 12 specific modifiable risk factors such as smoking, blood pressure and hearing loss. It’s now accepted that up to four in 10 dementia cases worldwide are linked to these factors. “This pioneering study shines important and much-needed light on factors that can influence the risk of young-onset dementia. This starts to fill in an important gap in our knowledge. It will be important to build on these findings in broader studies.” The study is published in JAMA Neurology.