Mielke and her colleagues examined data from the Prospective Population Study of Women, which began in 1968 and consisted of 1,462 Swedish women ages 38 to 60. Follow-ups were conducted at four intervals across the intervening decades, with the most recent examinations concluding in 2001. As part of the study, the women were given physical exams, heart tests, chest x-rays and blood tests. The group was also surveyed for smoking habits, alcohol and medication use, education and medical history. Throughout the study, body mass index (BMI), a measurement of weight-per-height, and blood pressure were taken. Women were assessed for dementia throughout the 32 years of follow-up between 1968 and 2001. In 2001, 161 of the original group had been diagnosed with Alzheimer's or other forms of dementia, but the youngest group was just reaching age 70.

Despite the advances being made in biomarker and other dementia research, the biggest known risk factor for these neurodegenerative diseases is old age.

Mielke says that later in life, women with slightly higher body mass index, higher levels of cholesterol and higher blood pressure tend to be healthier overall than those whose weight, cholesterol and blood pressure are too low. But it is unclear whether "too low" cholesterol, BMI and blood pressure are risk factors for dementia or if they could be signs that dementia is developing, she says. For example, an inadvertent loss of weight often precedes the development of dementia, she says, but the exact cause is unclear.

SOURCE Johns Hopkins University School of Medicine