Symptoms
What Is Cognitive Impairment?
Introduction
At times, the term "disordered thinking" is used interchangeably with "cognitive impairment", but technically speaking, disorders of thought involve abnormal thought content (delusions, hallucination, or ideas of reference) or thought process (loose associations, tangential thoughts, or flight of ideas). The distinction may be confusing.
Occurrence and Description
Cognitive impairment may occur before other symptoms of Schizophrenia. It involves problems with attention, concentration, memory, information processing and what is called “backward masking dysfunction”.
Problems with attention and concentration are similar, but distinct, problems. For example, individuals who suffer from Attention Deficit Disorder frequently experience problems with attention, but if they are interested in a subject or task, they often can establish and maintain concentration. People with depression often have problems with concentration. Attention could be thought of as focusing on a subject in the first place and concentration as maintaining that focus. People with Schizophrenia often experience both difficulties.
Furthermore, if we have problems with either attention or concentration, we will have difficulty retaining information (remembering it) due to impaired delivery to short-term and then long-term memory. Some individuals with Attention Deficit Disorder often do remarkably well in school in spite of their disability. This may be because they can attend long enough to allow information to be transferred to short term memory. People with depression, on the other hand, consistently experience problems in this area, probably because they cannot maintain concentration.
The problems that people with Schizophrenia experience with memory are often quite unique. They may encounter difficulty associating an event with the details of that event. In other words, they may remember the event itself, but be unable to recall when and where it occurred, or the circumstances surrounding the event.
The difficulties that sufferers of Schizophrenia experience related to information processing may involve information in general or the associations between pieces of information. When it involves the connections between words, it produces "word salad" where speech becomes unintelligible. They may associate words based upon similar sounds that they share; not because they have the same or related meanings or are naturally connected with one another. This results in what is referred to as “clang associations".
Backward masking dysfunction involves a person’s inability to remember a preceding event or concept. This may occur even if they have normal working memory. This has been attributed to some form of distraction, such as hallucinations, or some disturbing internal process.
Causes
Why do people with schizophrenia experience these difficulties? They are probably related to structural and functional abnormalities in their brains. Function has to do with activity and may represent reduced or increased levels of activity. Imaging techniques reveal these changes in the brains of people with Schizophrenia.
Medication Side Effects
Cognitive impairment may also occur as a medication side effect, from both medications used therapeutically and from those used to control other side effects. This source for these symptoms should always be considered when patients experience problems of this type.
Imagine Techniques
Imaging techniques such as MRI (Magnetic Resonance Imaging) and CAT (Computerized Axial Tomography) reveal a loss of brain tissue in people with schizophrenia, especially in the areas of the brain known as the prefrontal cortex and temporal lobes.
PET (Positron Emission Tomography), an imaging technique that reveals brain tissue activity rather than structure, demonstrates abnormalities in the brains of people with schizophrenia.
The prefrontal cortex affects logical thought, verbal memory and may affect clear and fluent speech. Aggression has also been linked to this area. Abnormally increased activity in the frontal and temporal lobes is associated with auditory hallucinations. Reduced tissue volume in the temporal lobes is related to problems in other areas of the brain that influence memory, emotions, as well as the occurrence delusions and hallucinations.
Summary
Cognitive impairment can be present as part of the constellation of symptoms that define Schizophrenia. When it is, the degree of impairment can be mild, moderate or severe.
It can also be present as a side effect of medications or as a result of some other psychiatric or medical conditions.
Abnormal structure and function in the brains of people with Schizophrenia is demonstrated by a variety of imaging techniques. These abnormalities may may be causally related to cognitive impairment.
(Sources: The author's knowledge base, unless otherwise noted.)
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