November 15, 2010
Women take note: High cholesterol in middle age not a risk factor for Alzheimer’s, other dementias
High cholesterol levels in middle age do not appear to increase women’s risk of developing Alzheimer’s disease and other forms of dementia later in life, new Johns Hopkins–led research finds, despite a body of scientific evidence long suggesting a link between the two.
What the study, published online Nov. 10 in the journal Neurology, does find is that women whose cholesterol levels decline from middle to old age are at 2.5 times greater risk of developing the memory-wasting diseases than those whose cholesterol stayed the same or increased over the years.
“Our research refutes the notion that high cholesterol in midlife is a risk factor for Alzheimer’s disease, at least among women,” said Michelle M. Mielke, an assistant professor of psychiatry at the Johns Hopkins University School of Medicine and the study’s lead author.
Even though Mielke and her colleagues found no link between high middle-age cholesterol levels and dementia risk, Mielke cautioned that people still need to watch their cholesterol, as high levels are linked to cardiovascular and other diseases. Cholesterol levels can be kept in check through diet, exercise and medication.
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. They also were surveyed for smoking habits, alcohol and medication use, education and medical history. Throughout the study, body mass index, a measurement of weight-per-height, and blood pressure were taken. Women were assessed for dementia throughout the 32 years of follow-up. 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 said 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 said. For example, she said, an inadvertent loss of weight often precedes the development of dementia, but the exact cause is unclear.
The study was supported by the National Institutes of Health, National Institute on Aging, National Institute of Neurological Disorders and Stroke, Swedish Research Council, Swedish Brain Power Project, University of Gothenburg, Swedish Council for Working Life and Social Research, Swedish Alzheimer Association, European Commission Seventh Framework Program, Svenssons Foundation, Swedish Society of Medicine, Soderstrom-Konigska Nursing Home Foundation, Foundation for Gamla Tjanarinnor, Hjalmar Svenssons Foundation, Swedish Society of Medicine, Goteborg Medical Society, Lions Foundation, Dr. Felix Neubergh Foundation, Wilhelm and Martina Lundgren Foundation, Elsa and Eivind Kison Sylvan Foundation and Alzheimer’s Association Zenith Award.
Peter P. Zandi of Johns Hopkins also participated in the study, as did researchers from SUNY-Downstate Medical Center in Brooklyn, N.Y., and the University of Gothenburg in Sweden.