The Anatomy of Madness

Schizophrenia

For the nation's one million schizophrenics, the extravagant delusions that come with the territory are as real as the perceptions of you and me. After all, they originate in the same place-the labyrinthine loops of the brain's neuronal networks.

Since 1809, when doctors first described schizophrenia, psychiatrists and neuroanatomists have searched for clues to explain why and how the disease occurs. But only recently have researchers discovered distinctive patterns of metabolic activity in the brains of schizophrenics. Using a scanning technique called positron emission tomography, or PET, they are glimpsing the brain in exquisite anatomic detail once thought unimaginable.

The kaleidoscopic images on PET scans suggest that there are structural defects in certain regions of schizophrenic brains which may lead them to process and retain information differently from healthy brains. Such alterations can produce behavior from the extravagantly bizarre to intense withdrawal, prolonged apathy, and other emotional or affective disturbances.

o In the brain's frontal lobes, PET scans show that the front-to-back ratio of blood is much lower in schizophrenic brains than in normal brains. Because these regions are vital in processing abstract thought, planning, and judgment, investigators believe this frontal lobe dysfunction may underlie the typical feelings of disorganization that often characterize schizophrenia.

o Abnormalities newly found in neural pathways that control memory and emotion may contribute to the troubles schizophrenics have retrieving information and linking the proper emotion to the proper circumstance. Carol A. Tamminga, M.D., and colleagues at the University of Maryland detected in schizophrenics greatly reduced metabolism of glucose, the brain's main fuel, in two structures--the subcortical hippocampus and the cingulate gyrus of the cortex.

Because the sea-horse shaped hippocampus is involved in memory function and the cingulate gyrus controls the body's emotions, neuronal underfunction here could explain, for example, why schizophrenics laugh at funerals or cry at inappropriate times, Dr. Tamminga and company report in Archives of General Psychiatry (Vol. 49, No. 7).

o The Maryland researchers also found that in certain types of schizophrenia, additional areas of the brain may also have lower levels of glucose metabolism. Schizophrenics with deficit symptoms such as reduced social interaction and thought paucity, for example, had significantly less glucose activity in the thalamus, and in the frontal and parietal cortex, compared to people with nondeficit schizophrenia.

Because the thalamic and cortical areas are integrally involved in accepting and processing sensory input from the environment, Dr. Tamminga and other scientists believe that abnormalities in these regions may alter or blunt the impact of external stimuli as they travel the pathway through the thalamus and into the cortex. As a result, deficit schizophrenics may actually experience a different world than the nondeficit or normal individual.

While the findings lend weight to the biological underpinnings of the disease, the diversity of the metabolic disarray has left scientists baffled. "No one knows for sure if schizophrenia is one illness, like diabetes, or a multiple illness like epilepsy and mental retardation," says Dr. Tamminga.

PARIETAL CORTEX

Regulates sensory function. Abnormalities here alter interpretation of external stimuli.

FRONTAL CORTEX

Key to abstract thought. Abnormalities here linked to schizophrenic feelings of disorganization.

CINGULATE GYRUS

The emotional center. Schizophrenic brains have trouble linking feelings to circumstances. Part of limbic system.

THALAMUS

Processes sensory input. Defects here blunt impact of external stimuli

HIPPOCAMPUS

Regulates memory function. Defects here hinder information retrieval. Part of limbic system.

DIAGRAM: The anatomy of madness (SCOTT MACNEILL)