Fish Oil, DHA & Dementia

Docosahexaenoic acid, or DHA, is one of the long-chain omega-3 fatty acids essential for healthy nervous system and brain functions. Fish oil found in fresh fish or supplements contains DHA. A healthy diet that includes fish oil may protect you from increased risk of health conditions including heart disease and dementia-related cognitive decline associated with the process of aging. Talk to your doctor before supplementing your diet.

About Dementia

Dementia is commonly associated with Alzheimer's disease, but it is actually a group of symptoms not necessarily linked to Alzheimer's. Cognitive decline including memory loss, inability to learn or remember new information, poor motor functions and personality changes characterize dementia. It has different causes and diagnosis depends on the brain area affected and symptom progression. Alzheimer's disease is the most common cause of progressive dementia and vascular dementia is the second common resulting from arterial damage to the brain and heart. Medical conditions linked to dementia include Huntington's disease, a genetic condition causing nerve cell wasting, or HIV-associated dementia. Reversible dementia from infection, immune disorders or nutritional deficiencies may be correctable with medical intervention, notes MayoClinic.com.

Fatty Acids and DHA

The three major omega-3 fatty acids in the diet include alpha-linolenic acid, or ALA, eicosapentaenoic acid, or EPA, and DHA. Fatty acids are named based on chemical composition, and in humans the fatty acids serve the general function of providing the structural and protective components of cell membranes. DHA is the most abundant fatty acid in human plasma and brain cell membranes. Through a metabolic process of desaturation and elongation, your body can convert ALA to DHA or get the fatty acid from DHA-rich dietary sources like fish, fish oil and supplements. However, the conversion of ALA to DHA is less efficient than consuming DHA directly. Your body does not create fatty acids on its own.

DHA and Dementia

In Alzheimer's disease and vascular dementia the outer nerve cells, or neurons, in the brain become coated with amyloid protein. This protein normally travels throughout the body but in the case of dementia it divides improperly and accumulates in the brain cells to form plaque, which becomes toxic to your neurons virtually smothering the cells. The exact reason amyloid plaque accumulates is not known. However, DHA consumption in early stage dementia may serve to protect your neurons from cell death by insulating cell membranes, increasing the neuroprotective enzymes and reducing oxidative damage, according to a 2010 review published in the "Journal of Nutrition."

Research Findings

Oregon Health and Science University researchers Dr. Joseph Quinn and colleagues presented the findings of the relationship of DHA to risk reduction of Alzheimer's dementia in a 2010 publication of the "Journal of the American Medical Association." According to the research, DHA supplementation did not change the progressive cognitive decline found in study participants over a two-year span. However, the researchers did indicate participants were already diagnosed with mild to moderate Alzheimer's and earlier intervention may yield different results.

Adequate Intake of Omega-3

According to the Linus Pauling Institute, adults are urged to consume 1.1 to 1.6 g per day of ALA containing foods or supplements. However, a standard intake of DHA has not been established, but you can get a direct source of this fatty acid from various fish like salmon, tuna and herring. Consumption of oily fish twice a week can provide adequate omega-3 fatty acids to promote heart and brain health. Consult your physician before adding supplements to your diet.