ADCS trial of DHA in mild to moderate Alzheimer’s disease

The results of the Alzheimer’s Disease Cooperative Study trial of DHA in people with mild to moderate Alzheimer’s disease show no evidence for benefit in the studied population. The authors say, "These trial results do not support the routine use of DHA for patients with Alzheimer’s."

The results were reported at the Alzheimer’s Association 2009 International Conference on Alzheimer’s Disease (ICAD 2009), in Vienna.

There was a possibly interesting finding in a secondary analysis of a positive trend (not statistically significant) on one test of mental function, known as the ADAS-cog, by study participants who did not have the Apoe-e4 gene, which is a known risk gene for Alzheimer’s. This deserves further study. No difference was seen on three other tests (global dementia severity status (CDR-SOB), activities of daily living (ADL), or behavioural symptoms (NPI)).

According to the Alzheimer’s Association, one of the issues raised by this study – and other recent Alzheimer’s and mild cognitive impairment therapy trials – concerns a possible interaction between certain therapies and genetic status.  This issue needs to be explored more completely in future trials.

The DHA study conducted by Martek Biosciences Corp. also showed an interesting result, in this case positive, but that study was in healthy older adults, not people with Alzheimer’s/dementia. We are uncertain of the "real world" benefit of the measured impact of the DHA supplementation. Even so, the results need confirmation, as is standard scientific practice.

These two studies – and other recent Alzheimer’s therapy trials – raise the possibility that treatments for Alzheimer’s must be given very early in the disease for them to be truly effective. For that to happen, we need to get much better at early detection and diagnosis of Alzheimer’s, in order to (a) test therapies at earlier stages of the disease and (b) enable earlier intervention.

Other research studies from ICAD 2009 show advances made in biomarkers and early detection through the Alzheimer’s Disease Neuroimaging Initiative (ADNI), and also survey results from doctors about the enablers and barriers they face in diagnosing people with Alzheimer’s.

(Source: Alzheimer’s Association: International Conference on Alzheimer’s Disease, Vienna: July 2009)