to give pain.
Very few psychiatrists appreciate that mental illnesses can also have a biological origin. It's worth remembering that numerous infections-syphilis, Chlamydia, typhoid, diphther-ia, HIV, herpes, rheumatic fever, malaria, urinary tract infection and even pneumonia-are well recognized by medicine to cause a range of psychiatric illness-from schizo-phrenia and bipolar disorder to auditory hallucinations.
Parasites of every variety, such as Giardia lamblia or trichinosis, are capable of taking up residence in our central nervous system, causing mental illness. Even simple bacteria like streptococci, which usually remain in our throats or skin, are also able to insinuate themselves into our brain.
Psychiatric symptoms appearing in later life can even have their foundation in prenatal exposure to a bug. A Johns Hopkins study involved 27 children, diagnosed with schizo-phrenia or other psychotic illnesses, whose mothers had been part of a Collaborative Perinatal Project in Rhode Island. When the researchers examined the stored maternal-blood samples for specific antibodies to infectious agents that might affect brain development, they discovered that the antibody levels to herpes simplex virus type 2 were far higher in mothers of the psychotic patients than in those of the controls (Arch Gen Psychiatry, 2001; 58: 1032-7).
The latest infection contributing to mental illness is the Lyme tick. Borrelia burgdorferi infection quickly invades the central nervous system, causing neurological and cerebral changes (Ann NY Acad Sci, 1988; 539: 16-23; Nucl Med Commun, 2002; 23: 773-7). A Czech study of nearly 1000 psychiatric patients found a higher prevalence of antibodies to B. burgdorferi than seen in healthy people (Am J Psychiatr, 2002; 159: 297-301).
Interestingly, the Borrelia spirochaete, the spiral-shaped organism that causes the illness, belongs to the same bacterial group as Treponema pallidum, which causes syphilis. Syphilis was called the 'great imitator' because its symptoms closely mimicked those of many other conditions. In fact, madness is a well-known symptom of the disease in its later stages.
Besides schizophrenia-like symp-toms (Biol Psychatry, 1999; 145: 795), chronic Lyme disease has been linked with anxiety, depression, confusion, aggressive behaviour, memory loss and fatigue-every psychiatric disorder in the Psychiatric Diagnostic Symptoms Manual IV. It's known to cause mental impairment in children, including autism and cognitive problems (J Neuropsych Clin Neurosci, 2001; 13: 500-7; Appl Neuropsychol, 1999;
6: 39-45). In one study at Columbia University, 20 children who'd been infected with the Lyme bug had significantly more psychiatric and cognitive difficulties, compared with the controls (J Neuropsych Clin Neurosci 2001; 13: 500-7). Even Alzheimer's patients have tested positive for the presence
of Lyme disease.
The ability of this new 'great imitator' to create many forms of mental illness has prompted the American Psychiatric Association to recommend that doctors and therapists first rule out Lyme disease before commencing psychological intervention.
Our 21st-century illness is far more complex than an ordinary infection. Perhaps the most sensible response to chronic illnesses such as autism is to think of it as a complex mix of what's present that shouldn't be (for example, parasites, or toxic metals or allergens) and what isn't present that should be (nutritional deficiencies). Doctors, in the main, assume that chronic disorders only have infective causes and insist on 'hunting the bug'. Although anyone presenting with a puzzling new mental illness should be screened for parasites first, with the complex illnesses we now face, it's important to hunt the bug and then look further.