Fish Oil Supplements Boost Memory

DHA Does Not Slow Alzheimer’s Progression

In the second study, researchers from the National Institute on Aging-supported Alzheimer's Disease Cooperative Study compared fish oil supplements to a placebo in 402 people with mild to moderate Alzheimer’s disease.

Participants took supplements containing either 2 grams of DHA or a placebo each day for 18 months.

“The hypothesis was that DHA would slow the rate of disease progression, but unfortunately that wasn’t the case,” says lead researcher Joseph Quinn, MD, associate professor of neurology at Oregon Health & Sciences University.

Treatment with DHA clearly increased blood levels of DHA, he tells WebMD, but memory worsened to a similar degree in both groups.

After 18 months, there was no significant difference between the two groups on any of the measures looked at, including a standard test that gauges the rate of deterioration of mental function.

DHA May Benefit Alzheimer’s Patients without ApoE-e4

Then, study participants were divided into two groups depending on whether they had the so-called ApoE-e4 gene variant. It’s associated with an increased risk of developing Alzheimer’s disease.

In the people who had the ApoE-e4 gene variant, there was again no benefit from DHA treatment. In contrast, those without the ApoE-e4 gene variant who received DHA had a slower rate of memory decline.

“This is an intriguing provocative result, but requires further study for confirmation,” Quinn says.

He says it’s a mistake to compare this study to the one in healthy adults because they looked at such “very different populations of patients.”

But the conflicting findings raise the possibility that treatments for Alzheimer’s have to be given “very, very early” to be effective, Thies says.

Martek funded the study in healthy adults and provided the supplements for both studies.