Scientists followed a group of Swedish women for three decades -- from middle age to old age -- and found no increase in Alzheimer’s risk among women whose cholesterol was high in their 40s, 50s, and 60s.
The finding appears to contradict several earlier studies, which did suggest a role for elevated midlife cholesterol in the development of late-life dementia.
But many of those studies only included people who survived long enough to develop Alzheimer’s disease, which could have influenced the outcomes, says researcher Michelle M. Mielke, PhD, who is an assistant professor of psychiatry at Baltimore’s Johns Hopkins University School of Medicine.
“Because we followed people from middle age, we were able to look at the predictive value of cholesterol levels for developing dementia,” she tells WebMD.
The study included 1,462 women, most of whom were in their 40s and 50s at enrollment.
All the women had physical exams and completed lifestyle surveys when they entered the study and at various times later on. Neuropsychiatric exams were performed over the 32 years of follow-up. Women who survived to age 70 also underwent more extensive periodic testing for dementia.
During 32 years of follow-up, 161 women developed dementia.
The researchers concluded that cholesterol levels measured in middle age did not predict progression to Alzheimer’s disease later in life.
But a link was seen between rapidly declining cholesterol levels in the elderly and dementia.
Women whose cholesterol decreased the most from middle age to old age were more than twice as likely to develop dementia as women whose cholesterol levels increased or stayed the same.
Mielke says rapidly declining cholesterol late in life appears to be associated with increased frailty and may be an early sign of dementia.
“Around 10 years before people develop symptoms of dementia they tend to become more frail,” she says. “They may be forgetting to eat and start to lose weight, which can impact cholesterol levels.”