There is mounting evidence that low levels of n-3 polyunsaturated fatty acids (PUFAs) play a role in the pathophysiology of a number of psychiatric disorders. Preclinical studies have shown that n-3 PUFAs decrease anxietylike behaviors, but there is a paucity of information about their effects on anxiety in humans. In light of our observation that substance abusers have poor dietary habits and the strong association between anxiety disorders and substance use disorders, the possibility that the administration of supplements of n-3 PUFAs would decrease the anxiety level of a group of substance abusers was explored.

Thirteen patients were given on a daily basis capsules containing 3 g of n-3 PUFAS (eicosapentaenoic acid + docosahexaenoic acid). Eleven patients received similarly looking placebo capsules containing vegetable oil. The trial was double-blind, randomized, and lasted 3 months. A scale assessing anxiety feelings was administered at baseline and on a monthly basis thereafter. Six PUFA group patients and 8 placebo group patients were followed for an additional 3 months after treatment discontinuation and administered the same questionnaire monthly.

Patients who received n-3 PUFAs for 3 months showed a progressive decline in anxiety scores. This was not the case for patients who received placebos. A comparison of the 2 groups was significant (P = 0.010). Anxiety scores remained significantly decreased in the PUFA group for 3 months after treatment discontinuation. A comparison of the 2 groups followed for 6 months was also significant (P = 0.042).

In conclusion, these preliminary data indicate that n-3 PUFA supplementation could be beneficial in the treatment of some patients with anxiety disorders.