Unravelling risk factors
Observing large groups of people over a long time can help researchers understand the impact of dementia and track trends linked to the condition. These are called longitudinal studies and can link lifestyle factors, pre-existing health conditions or drugs used to treat other diseases to an altered risk of dementia. It can be hard to separate cause and effect from these studies, but they can make powerful observations with important implications for healthcare.
Age is the biggest risk factor for dementia, but research suggests that factors throughout life could also influence our brain health in old age.
Higher education early in life, better occupation in midlife and greater social engagement later in life appear to offer some protection against dementia. Some scientists believe these activities may structurally and functionally strengthen our brains and make them more resistant to the effects of diseases like Alzheimer’s. This is called ‘cognitive reserve’ and could help our brains compensate for the damage taking place.
Lifestyle factors such as poor diet, physical inactivity, heavy drinking, midlife obesity and smoking can increase our risk of dementia, as well as existing health conditions such as high blood pressure in midlife, high cholesterol, depression, diabetes, stroke and Parkinson’s. Due to their genetic makeup, around 60% of people with Down’s syndrome will develop Alzheimer’s by the age of 60.
Studies following World War II veterans, boxers and American football players are also suggesting head injury as a risk factor for dementia and this is an active area of research.
It is important to understand dementia risk factors in context. Research suggests diabetes increases a person’s risk of Alzheimer’s by around 39%. But what does this really mean? Around 6% of the world’s population has diabetes, so the condition is thought to contribute towards 2.4% of Alzheimer’s cases. This doesn’t sound like much, but it could be as many as 826,000 cases of Alzheimer’s worldwide.
While not all dementia can be prevented, as many are caused by a complex mix of genes and environment, it has been estimated that delaying the onset and progression of Alzheimer’s by as little as one year could result in 9.2 million fewer cases across the world by 2050.