If your body has low levels of EFA's the myelin sheath, the covering protecting the nerves, may not built up enough  therefore unable to store the neurotransmitters thus the linked to ADD and Dyslexia, as recent research indicates. 

Approximately 70% of the myelin sheath is made up of cholesterol and fatty acids.  It's no wonder if a diet low in these causes so many problems with our children and adults alike.  It effects may vary from individual to individual.

Depression is another direct link to low levels of these good fats.

"When researchers monitor eating habits across countries, they find that as fish consumption goes up, depression rates go down.  In fact, there is a sixty-fold difference in depression rates across countries from the highest  (Japan and Taiwan) to the lowest (North America, Europe and New Zealand) omega-3 fat consumption. 

Also note worth is that postpartum depression decreases as women increase their consumption of fish.  Many people also report a drop in mood when they switch to a low-fat diet.

There have been increasing studies over the last decade by neuroscientists examining the consequences of Omega-3 deficiencies in the central nervous system.

 From the studies we can conclude that Omega 3 oils:

• Alter the serotonin and dopamine levels, two very important neurotransmitters.
• Compromises the blood-brain barrier, which protects the brain from unwanted invaders.
• Decreases normal blood flow to the brain
• 35% reduction in brain phosphatidylserine (PS) levels (antidepressant activity)

Trying to choose more healthy nutrients, people often turn to transfatty acids, such as margarine and shortening  which destroy the essential nutritional character of the oils and block the use of normal essential fatty acids, which are necessary for healthy cell function.