March 30, 2007

Understanding Where the Brain Goes Wrong in Schizophrenia

Dr. Robert Freedman, M.D., in the American Journal of Psychiatry, discusses recent findings from different studies of the brains of patients living with the sensory processing problems and auditory hallucinations of schizophrenia. The studies used techniques such as EEG, magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI).

Some salient points were made regarding several topics of inquiry.

  • Information Processing: Many people with schizophrenia are unusually aware of stimuli (sound, sight, smell, etc) in their surroundings. Patients have problems discriminating important from unimportant information they recieve from their environment both because of an inability to select what they respond to plus an inability to filter out distracting stimuli to not respond to.

  • Out of Sync Brain Cells and Positive Symptoms: When the brain is in "idle mode", interconnected processing of activity is supposed to show (via fMRI), regular, rythmic activity. Instead, correlated with positive symptoms, patients' brains show that some portions are over-active and some parts under-active, with the entire circuit unable to stabilize itself. (See here)

  • Sensory Gating and Attentional Modulation Problems: As shown by EEG, even in sleep, there is an area of the brain that is underactive. This underactive area of the brain while awake could cause attentional problems and sensory gating deficits.

    Attentional modulation is the ability to shift attention to different tasks and to different details according to "importance".

    Sensory gating is the the process in which the brain adjusts to sensory stimuli (such as a repetitive loud sound). When there is a problem with sensory gating, the person can be overwhelmed by the sensory stimuli.

  • Deficits in Detecting Prosody (Tones): An inability to detect both emotions and incorrect tunes (see here) was related to worse connections in the auditory part of the brain. It was also found that these patients can have difficulty distinguishing a question from a statement based simply on inflection of the voice.

  • Myelin and Auditory Hallucinations: There is degraded neuronal myelin (the fatty coverings of brain cells) in some areas of the brain. But, in people with auditory hallucinations, the brain cells in the auditory area do not have this problem.

    Dr. Freedman says that this is "evidence that the strengths left to persons with schizophrenia sometimes exacerbate the signs of their illness. More intelligent patients have long been known to have more difficult and persistent paranoia. Here a more intact auditory system ends up to be the substrate of increased auditory hallucinations."

Dr. Freedman compares figuring out the areas affected in the brain of a patient with schizophrenia by the patient's symptoms, to the neurologist’s evaluation of a stroke - the symptoms reflect the area of the brain affected. He says these studies "reaffirm to us the burden of illness that patients face in trying to approach even very simple tasks." It can explain how patients are affected by sensory stimuli, and how they may be compensating for deficits, and how some behaviors, which may be annoying to family members, may be coping strategies for the patient.

Dr. Freedman suggests that it may sometimes be helpful to tell patients a bit about how their brains may be malfunctioning, and to use this to enhance understanding between patients and their families.

Read the full article: Neuronal Dysfunction and Schizophrenia Symptoms

Related Reading:
Connection Between Schizophrenia and Not Understanding Emotional Tone of Speech

In Schizophrenia, Brain's Default Mode Seems to be Out of Sync

Excessive Startle Response in Schizophrenia

Biological Basis of Hallucinations

Blame Myelin For Many Neuropsychiatric Disorders

Gene linked to schizophrenia also tied to intelligence


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