Among the leaders in this field of study are the practitioners and researchers at the Pfeiffer Treatment Center in Naperville, Illinois, USA. Based on the work of the late Carl Pfeiffer, a professor at Princeton University, the centre is involved in both research and the nutritional treatment of a wide range of mental disorders.

Researchers at the Pfeiffer Center have found that most victims of mental disorders fall into one of three main biochemical classes: low histamine; high histamine; and pyroluric. The Center’s scientists have also discovered that excess copper and toxic overload can contribute to certain types of depression (see box above).

Low-histamine, or histapenic, individuals are ‘over-methylated’. Around 25 per cent of those with bipolar disorder, and 20 per cent of depressives, 45 per cent of schizophrenics and 15 per cent of those with autism are thought to be histapenic.

Methyls are chemicals consisting of one carbon and three hydrogen atoms. Over-methylated individuals possess too many of these methyls, resulting in excessive levels of the neurotransmitters dopamine, norepinephrine and serotonin. These people are usually nervous and anxious, and prone to paranoia and despair. Generally free of seasonal allergies, they often report a multitude of food and chemical sensitivities. They may also have a history of underachievement, hyperactivity and learning disability.

In contrast, high-histamine, or histadelic, depressives overproduce and retain excess levels of histamine, an important neurotransmitter that affects human behaviour. They are said to be ‘under-methylated’, with low levels of serotonin, dopamine and norepinephrine. They represent 35 per cent of all cases of bipolar disorders, half of all depressives, 18 per cent of schizophrenics, 45 per cent of those with autism and nearly all of those with obsessive-compulsive disorder and anorexia/bulimia.

Symptoms in these patients can include seasonal variations in depression, obsessive-compulsive tendencies, inhalant allergies and frequent headaches as well as perfectionism, high libido and sparse body hair. Such individuals may appear outwardly calm, but suffer from extreme internal anxiety.

About 20 per cent of those labelled bipolar have a genetic pyrrole disorder. This is associated with high kryptopyrrole production as well as fatty-acid abnormalities - especially depressed arachidonic acid - very poor immune function and severe metal-oxidative stress. Rapid-cycle patients - those who experience more than four manic-depressive episodes a year - are often affected by pronounced pyrrole disorder. Around 18 per cent of those with bipolar disorder, 20 per cent of depressed individuals, 27 per cent of schizophrenics and 20 per cent of autistic people have this disorder, compared with 10 per cent of the general population.

Pyrolurics are devastated by stress such as physical injury, emotional trauma, illness and sleep deprivation. These individuals often report an inability to eat breakfast, sensitivity to light and noises, reading disorders, hysteria, rage, severe anxiety, absence of dream recall and frequent infections.

These categories, of course, are general and some crossover among them is inevitable. For instance, a person can be histadelic, but suffer from the same types of imbalances seen in pyroluria as well.

Individualised treatment The Pfeiffer Center programme involves asking a basic question that few other practitioners ask: who is the patient nutritionally? Finding the answer involves extensive chemical analysis of blood, urine and tissues to define the patient’s biochemistry. Treatment requires supplements of specific vitamins, minerals and amino acids (see box above) that need to be supplied with rifle-shot precision - and sometimes in very high doses.