Home > Memory > Memory in People With Schizophrenia: What is Impaired, What is Preserved?

Memory in People With Schizophrenia: What is Impaired, What is Preserved?

One in four: This is the proportion of Americans living today that have suffered from a diagnosable mental illness within the last year (“Mental Illness,” 2011). Examining this statistic, it is clear that the effects of mental illness are widespread. In the US, for example, costs for direct treatment of mental illness are estimated to be US$ 148 billion annually, and indirect economic costs – like lost employment (due to medical leave) and decreased productivity, are two to six times higher than that (Panthare, 2003).

If you yourself aren’t directly afflicted with a disorder, chances are someone in your immediate or extended family may be. The outward physical manifestations of these disorders may be minimal for those possessing them, making them seem at times like “invisible illnesses;” that is, you may not be able to tell that someone has one of these disorders simply by looking at them. Complicating things even further for individuals with a mental disorder, many who are afflicted may not have received a proper diagnosis or are struggling without professional medical help.

Schizophrenia is one such disease that can be quite debilitating for those suffering from it. The disorder has the ability to impact thoughts, the senses, mood, judgment, personality, and memory. Individuals with schizophrenia often experience hallucinations – that is, they see, smell, hear, or feel things without the presence of an actual external stimulus; they perceive these things that are not actually present. They may also have delusions, or beliefs that are often illogical and false, and sometimes exhibit thought disorders, or odd and dysfunctional ways of thinking (“What are the Symptoms,” 2009). These impairments often make it difficult for individuals with schizophrenia to find and hold stable jobs, form new relationships, and function and perform effectively in school and other social settings.

Psychologists have recently explored the nature of the impairments that make these everyday tasks so difficult for individuals with the disorder.  Robert Kern (2010) and his colleagues examined schizophrenia and memory, and specifically explored the differences in memory functions between people with schizophrenia and community members without the disorder. The researchers hoped to indicate a specific pattern of memory functions that are impaired for people with schizophrenia and a pattern of those functions that are preserved. They examined both declarative memory, or the conscious memory of facts, events, and knowledge, and nondeclarative memory, defined as memory based on an ability to recall how to perform certain procedures, some of which are associated with skills (Kellogg, 2007). An example of a declarative memory would be remembering that the capital of the state of Maine is Augusta, whereas an example of nondeclarative memory would be the muscle memory of the process associated with successfully shooting a basketball into a hoop.

Kern et al. specifically assessed seven sub-types of declarative and non-declarative memory. These included five measures of declarative memory: verbal learning, working memory, semantic memory, remote memory, and verbal retention. Verbal learning is the retention of verbal information like words; working memory involves actively maintaining thoughts, or mental representations, so they can be manipulated, like doing math in your head; semantic memory is one’s memory for meanings and facts; remote memory is the ability to remember things that happened years ago, like your fifth birthday; and verbal retention is the storage of previously learned verbal information over a long period of delay (Kellogg, 2007). Realistically, impairment in any of these memory processes could make daily functioning difficult.

The researchers also examined two measures of nondeclarative memory: procedural memory and priming. Procedural memory is memory of how to perform specific actions or procedures, like performing a memorized, elaborate dance, whereas priming is an effect in which the presentation of an initial stimulus impacts the way a future stimulus is perceived. For example, a person who views the word  “yellow” be faster to recognize the word “banana” than someone that views the word “pink” because of the association between “yellow” and “banana.”

In this study, a battery of memory tests assessing these seven measures of memory was given to 40 outpatients diagnosed with schizophrenia and 30 community members without the disorder. Each of the seven tests was designed to give a numeric measure of the participants’ capabilities for one of the specific memory functions.

The results of the study showed that individuals with schizophrenia, compared to individuals without the disorder, are impaired on measures of verbal memory, working memory, semantic memory, remote memory, and priming. Interestingly though, the two groups showed comparable levels of performance on tasks measuring verbal retention and procedural learning. Thus, individuals with schizophrenia did not differ in their ability to retain learned verbal information across a long period of time, and had a maintained memory for how to carry out certain procedures, but other memory functions were significantly impaired. These findings give insight into how individuals with the disorder are impaired in the workplace, at home, or in the classroom. They may have difficulty remembering instructions because of impaired verbal memory, or may perhaps have difficulty solving problems or thinking creatively because of a deficit in working memory. It is also probable that the impairments in differing memory systems combine to exacerbate memory problems, making functioning especially difficult.

These findings have tremendous potential for influencing and guiding future treatment plans for individuals with schizophrenia. Verbal memory, working memory, semantic memory, remote memory, and priming are now identified as specific areas of memory that therapists may in the future look to strengthen for these individuals. Focus in these areas may help individuals dealing with the disorder overcome the daily challenges they face and allow them to move towards being able to lead normal lives. Additionally, the areas of procedural memory and verbal retention may in the future be emphasized by therapists as positive areas in the lives of individuals with schizophrenia that they can build upon and strengthen further. Ultimately, this study by Kern et al. (2010) has clearly identified a specific pattern of memory impairment for individuals with schizophrenia, and helps to focus future treatment and rehabilitation efforts.

 

Kellogg, R. T., (2007). Fundamentals of cognitive psychology. Los Angeles, CA: Sage Publications.

Kern, R. S., Hartzell, A. M., Izaguirre, B., & Hamilton, A. H. (2010). Declarative and nondeclarative memory in schizophrenia: What is impaired? What is spared? Journal of Clinical and Experimental Neuropsychology, 32, 1017-1027. doi: 10.1080/13803391003671166

Mental illness: Facts and numbers. (2011). Retrieved April 24, 2013, from http://www.nami.org/Template.cfm?Section=About_Mental_Illness&Template=/ContentManagement/ContentDisplay.cfm&ContentID=53155

Pathare, S. (2003). The mental health context. Retrieved from World Health Organization website: http://www.who.int/mental_health/resources/en/context.PDF

What are the symptoms of schizophrenia? (2009). Retrieved April 25, 2013, from http://www.nimh.nih.gov/health/publications/schizophrenia/what-are-the-symptoms-of-schizophrenia.shtml

Here is a link to the article.

 

  1. May 19th, 2013 at 02:07 | #1

    This article is fascinating! I was particularly surprised that long term verbal retention was maintained even though working memory was deficient. Attention and working memory are so important for the retention of items. One would think that deficits in working memory would cause long term memory to suffer. I wonder why this does not happen. I agree with Anne’s comment that these patients should be tested against those with attentional deficiencies such as ADD or DAT. It would be fascinating to see the similarities and would be an attempt to further understand schizophrenia through looking at the differences present between these particular cognitive abnormalities.

  2. May 18th, 2013 at 13:14 | #2

    I agree that this is a really interesting line of research. This could also provide a lot of relief for people with schizophrenia that struggle with unexplained memory issues. I wonder if medication for schizophrenia symptoms alleviates any of the memory issues that are clearly affecting people. This research could have implications for early diagnosis in patients with emerging symptoms. Since the symptoms of schizophrenia are very distracting (hallucinations, paranoia, etc.), I wonder if this has a negative effect on attention. Maybe attention issues also help account for poorer performance on memory tasks because it is harder to learn new information or keep it in your memory when you’re distracted. It would be interesting to try these tests with patients experiencing highly distracting symptoms versus schizophrenics taking antipsychotics or undergoing therapy. I wonder if this would have a positive effect on working memory, and if so, maybe encourage more people to seek treatment (or fund treatment!).

  3. May 14th, 2013 at 14:58 | #3

    Wow! This article is incredibly interesting and seems to be quite ground-breaking. Schizophrenia is the type of disorder that one would typically classify as just a general dissociation from reality, and its accompanying effects, such as the hallucinations and false beliefs that you discussed. From what I have read and heard about schizophrenia, it is never thought to be a “memory” disorder – so seeing that it has such a humongous effect on memory is honestly astounding! It is similar to how most people believe that Alzheimer’s is a disorder that affects solely memory, but in reality, Alzheimer’s is a complicated disorder that is as debilitating, if not more, to attention as it is to memory. The findings in this study definitely could change the way schizophrenia is treated. I wonder what kind of effects memory therapy has on schizophrenia – has there been any kind of results on that treatment yet? If it has a positive effect and improves the lives of those with schizophrenia, then this research is really amazing. Great post, Ben!

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