High serum total cholesterol levels in midlife increase the risk of
developing Alzheimer's disease 3 decades later, new research shows.

Alzheimer's disease was 1.5 times more prevalent in men and women
who had total cholesterol levels of 249 to 500 mg/dL when they were
middle-aged than in people with normal cholesterol levels, according
to a retrospective study that involved 9752 members of a Kaiser
Permanente health plan in northern California.

The study results send a message to physicians, study coauthor Alina
Solomon, MD, from the University of Kuopio, in Finland, who
collaborated with researchers at Kaiser Permanente, told Medscape
Neurology & Neurosurgery: "Minding heart health may protect the
brain."

Dr. Solomon presented the results here at the American Academy of
Neurology (AAN) 60th Annual Meeting.

Heart Health

In this multiethnic cohort, the patients were 40 to 45 years old
when they had health evaluations between 1964 and 1973. They stayed
with the health plan through at least 1994, so that the researchers
were able to check their most recent medical records, from 1994 to
2007, for a documented diagnosis of Alzheimer's disease.

On retrospective chart review, the authors found that 504 patients
had Alzheimer's disease, with a mean age at diagnosis of 68.8 years.
High cholesterol increased Alzheimer's risk regardless of midlife
diabetes, hypertension, and obesity; smoking; and late-life stroke,
according to Dr. Solomon.

They found that subjects in the highest quartile for cholesterol
level in their 40s had an increased risk for AD compared with those
in the lowest quartile.

Even less severely elevated cholesterol was associated with an
increased risk for dementia, said Dr Solomon. Patients whose total
cholesterol levels were between 221 and 248 mg/dL were still more
likely to have a diagnosis of Alzheimer's disease later in life
compared with patients with cholesterol levels below 198 mg/dL.

Possibly, the study underestimated the risk of Alzheimer's disease,
Dr. Solomon said in an interview with Medscape Neurology &
Neurosurgery. Some patients may have had the disease, but it was not
yet diagnosed at the most recent visit, she theorized. In addition,
she said, some patients may have received lipid-lowering medications
when they became available, but the authors did not have this
information.

Because the data from the 1960s and early 1970s did not have
information on triglycerides and low-density-lipoprotein (LDL)
cholesterol, the authors were unable to analyze whether these
measures had an effect on Alzheimer's risk.

The researchers did observe a trend toward an increased risk for
vascular dementia in this patient population, but the difference was
not statistically significant, according to the abstract.

Based on their study findings, Dr. Solomon advised physicians not to
delay in treating patients in their 40s who have high cholesterol
levels. She said she would prescribe dietary and other lifestyle
modifications first and, if necessary, medication. However, it is
not yet clear whether statins will protect against the development
of Alzheimer's disease, she stated.

A "Hot Topic"

A study published online January 16 in Neurology found that statin
use did not lower the risk of Alzheimer's disease.

That study's principal author, Zoe Arvanitakis, MD, associate
professor in the department of neurological sciences at Rush
University Medical Center, in Chicago, Illinois, spoke to Medscape
Neurology & Neurosurgery after viewing Dr. Solomon's poster at the
AAN meeting. Their study had important differences from the new
study in that it looked at patients in their late 70s, she said, and
their follow-up was only for up to 13 years.

"It may be that you need to take statins a lot longer to benefit,"
said Dr. Arvanitakis, who had no relationship with Dr. Solomon's
research. "This is a hot topic and an ongoing story."