Abnormal brain blood flow persisting in some Gulf War veterans

December, 2011

In a small study, some Gulf War syndromes are shown to have effects on the hippocampus that have persisted for 20 years, and in some cases worsened.

So-called ‘Gulf War syndrome’ is a poorly understood chronic condition associated with exposure to neurotoxic chemicals and nerve gas, and despite its name is associated with three main syndromes: impaired cognition (syndrome 1); confusion-ataxia (syndrome 2); central neuropathic pain (syndrome 3). Those with syndrome 2 are the most severely affected. Note that the use of the term ‘impaired cognition’ for syndrome 1 is not meant to indicate that the other syndromes show no impaired cognition; rather, it signals the absence of other primary symptoms such as ataxia and pain.

Symptoms of Gulf War syndrome include fatigue, neuropathic pain, memory and concentration deficits, balance disturbances and depression. Many of these symptoms suggest impairment of the hippocampus (among other regions, in particular the basal ganglia).

The new study follows up on an earlier study, with many of the same participants involved. A new, more sensitive, technique for assessing blood flow in the hippocampus was used to assess 35 patients with Gulf War syndromes and 13 controls. In the study of eleven years previous, those with syndrome 1 (impaired cognition) showed similar responses as the controls, while those with syndrome 2 (confusion-ataxia) showed abnormal blood flow in the right hippocampus.

In the present study, that abnormal hippocampal blood flow had progressed to the left hippocampus for those with syndrome 2 and to both hippocampi for those with syndrome 3. The results indicate that this alteration of hippocampal blood flow persists and can even worsen.

Around a quarter of U.S. military personnel deployed to the 1991 Persian Gulf War are estimated to be affected by Gulf War syndrome. Previous research has suggested genetic variation may underlie individuals’ vulnerability to neurotoxins.