In this large randomized trial among Alzheimer's patients, 2.0 g DHA did not bring any benefit in terms of memory function

1. www.pronutritionist.net
Docosahexaenoic acid
supplementation and cognitive
decline in alzheimer disease
A Randomized Trial
Quinn J et al
JAMA 2010; 304:1903-1911
Page 1 Quinn J et al. JAMA 2010; 304: 1903-1911

2. Page 2
Pronutritionist’s background
• Omega-3 fatty acids has been proved to reduce risk of
Alzheimer disease in epidemiologic studies
• In addition, Mediterranean diet might protect from cognitive
impairment (Scarmeas et al. 2009)
– contains lots of fish, nuts and vegetable oils, which are good sources of
omega-3 fatty acids, including DHA
• High intake of saturated fat has been linked to cognitive decline
(Devore et al 2009, Morris et al. 2006)
• In previous randomized trials omega-3 fatty acids have showed
some promise in preserving cognition ( Chiu et al. 2008), but
outcomes have been conflicting (Freund-Levi et al 2006, van de
Rest et al. 2008)
Quinn J et al. JAMA 2010; 304: 1903-1911 www.pronutritionist.net

3. Methods
• A randomized, double-blind,placebo-controlled trial
• n = 295
– mean age 76 ± 8,7
– individualswith mild to moderate Alzheimer disease
(Mini-Mental State Examinationscores 14-26)
• Duration of treatment18 months
– participants were randomized to DHA 2 g/d or placebo
• Main outcome measures:
– change in the cognitive subscaleof the Alzheimer’s
Disease Assessment Scale (ADAS-cog)
– change in the Clinical Dementia Rating (CDR) sum of
boxes
– rate of brain atrophy was determined in a subsample of
participants (n = 102)
Page 3 Quinn J et al. JAMA 2010; 304: 1903-1911 www.pronutritionist.net

4. Results
• Supplementation withDHA had no beneficial effect on
– rate of change on ADAS-cog score
– rate of change on the CDR sumof boxes score
• In the subpopulation of participantsthe rate of brain
atrophy was not affectedby treatment with DHA
– mean decline in total brain volume was 24.7 cm3
in the DHA group
and 24.0 cm3
for the placebo group
www.pronutritionist.netQuinn J et al. JAMA 2010; 304: 1903-19114

5. Results: ADAS-cog score
Page 5 Quinn J et al. JAMA 2010; 304: 1903-1911 www.pronutritionist.net

6. Results: CDR
www.pronutritionist.netQuinn J et al. JAMA 2010; 304: 1903-19116

7. Pronutritionist’s discussion
• In this study, supplementation with DHA compared with
placebodid not slow the rate of cognitive and functional
decline inpatients with mild to moderate Alzheimer disease
when using ADAS-cog and CDR scales
• In another study from Yorko-Mauro et al (2010) DHA
supplements improved some cognitive parameters in mild
cognitive impairment
• It is possible that it’s too late introduce DHA supplements in
established AD
• Authors speculate that DHA supplements may require
concomitant antioxidant usage to materialize the full potential,
as it is shown in some studies
• It’s also possible that the effects of DHA supplementation are
restricted to sub-population of AD (APOE 4–negative
individuals)
www.pronutritionist.netQuinn J et al. JAMA 2010; 304: 1903-19117