Fish Oil Brain Delivery Study

• The investigators goal is to study how different people deliver DHA to the brain.
• The study will only require two visits six months apart and involve taking DHA during these 6 months.
• Participants will receive DHA supplements for the study duration and a compensation for each study visit.
• Blood and cerebrospinal fluid levels of DHA will be measured before and after taking DHA.
• Brain imaging by MRI will be obtained at baseline and at conclusion of study
• This study will help us learn how much of the ingested DHA goes to the brain.

Inclusion criteria

• ages 55 and above
• at risk of Alzheimer's disease such as family history of dementia
• women have to be postmenopausal

Exclusion criteria

• Current smokers (or a recent history of smoking within less than 5 years),
• Having a history of cardiovascular disease defined by a prior heart attack, coronary bypass or percutaneous luminal angioplasty, kidney failure or blindness.
• a diagnosis of cancer in the past 6 months, uncontrolled hyper- or hypothyroidism
• Taking anti-coagulants such as warfarin
• Anyone consuming n-3 PUFA capsules for the last 3 months.
• regular exercisers (>5 X30min of aerobic exercise per week),
• heavy drinkers (>30 units of alcohol per week). One unit of alcohol is about equal to: half a pint of ordinary strength beer, lager or cider (3-4% alcohol by volume); or. a small pub measure (25 ml) of spirits (40% alcohol by volume); or. a standard pub measure (50 ml) of fortified wine such as sherry or port (20% alcohol by volume)
• If participants have scores that lie 2 SD outside the means of the neuropsychiatry tests administered, they will have mild cognitive impairment. Participant's with mild cognitive impairment are excluded from this study.