by: Jacinda Taggett.
Frankie sat across from her friend, Kieran, on an evening in the winter of 2021. The two were having a conversation about Frankie’s current state, which had been abnormal. Frankie was currently undergoing a psychotic episode, and her cognition displayed impairments during their talk. Randomly, when prompted a question, Frankie would lose her train of thought midway through the sentence, and lose track of the question itself. This made the conversation with Kieran difficult, as he had to continuously remind Frankie of what was going on, while she stared blankly at the countertop and was unable to stay attentive.
Frankie’s time in college was more difficult during this episode, as she could not keep track of her lectures. She was convinced that her professor and classmates were listening to her thoughts, which made her wary of going to lecture. Doing assignments took longer than usual, since she would be unable to comprehend what she was reading before herself.
Some of these cognitive deficits were repaired once Frankie became medicated again, but some of these features still persisted. What Frankie suffers from is a working memory deficit, common in people with psychotic features. Specifically in a disorder called schizophrenia, these cognitive deficits continue even after becoming medicated. In this article, we will be discussing the impact that working memory deficits have on individuals with schizophrenia, and how it affects their everyday life.
Working Memory
Working memory, as we know it today, was first proposed by Baddeley and Hitch (1974). They claimed that memory was split into two, long-term and short-term. Working memory is the official name for what we consider to be short-term memory. This type of memory is known for temporarily storing information, and manipulating it when we need to do so. It can be thought of as the mental process in which someone has to solve a math problem, remember a note before they write it down, or have the capability to drive (even without remembering the process afterwards). Working memory is particularly important for everyday tasks, such as maintaining a conversation or being able to recall where an item was placed just moments before. When working memory becomes impaired, it becomes difficult for people to function normally.
Schizophrenia
One of the most misunderstood neurological disorders is schizophrenia, which is a disorder that is characterized mostly by its prevalence of hallucinations and delusions. It is oftentimes confused with dissociative identity disorder, previously known as multiple personality disorder. Other times, even when correctly identified by the general public, individuals with schizophrenia are considered dangerous or suspicious people. Schizophrenia is a debilitating mental disorder, which typically causes more suffering and harm for the specific individual rather than the people around them.
According to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM–5; American Psychiatric Association, 2013), individuals must have at least one positive symptom and one or more other symptoms (either positive or negative) for at least a month, and general disturbance in everyday life for over 6 months.
Positive Symptoms
Characterized as either psychotic or disorganized symptoms, positive symptoms of schizophrenia are the most notable part of the disorder. Psychotic symptoms include hallucinations and delusions. Hallucinations are when an individual experiences an activation of their senses (i.e., sight, hearing, touch, etc.). An example of hearing a hallucination is if you were to be sitting in a quiet library and then hear a voice telling you “Go to that shelf” when no one in person is addressing you. Delusions, on the other hand, are beliefs that are not perceived in reality. These beliefs also typically affect everyday living significantly, like how Frankie’s delusion of everyone reading her mind impacted her education.
Disorganized symptoms often involve thought, speech, and behavior of an individual. Oftentimes, these would appear as an inability to communicate properly, and have the individual speak like a broken robot, randomly generating words. This condition is deemed “loose associations” and often impairs the individuals’ thoughts. Disorganized behavior is another positive symptom of schizophrenia, which makes it difficult for an individual to begin or finish tasks.
Negative Symptoms
The negative symptoms of schizophrenia are often the emotional and social aspects of the individual. These symptoms include a lack of emotional expression or feeling (i.e., happiness or motivation), and minimal socialization or communication.
Cognitive Deficits
Cognition that is affected by schizophrenia include attention, processing speed, memory (both long-term and short-term), and learning. These deficits typically impact an individual’s everyday life without them being aware of it occurring. Working memory will be the focus of this article, as it usually encompasses all aspects of cognitive functioning listed previously.
Cause of Schizophrenia
Although the direct cause of schizophrenia is unknown, the main hypothesis for decades has been that the neurological basis is an imbalance of dopamine in the brain. Dopamine is one of the most well-known but reasonably misconceived monoamine neurotransmitters (a neuron’s set of keys) in psychological and neuroscientific discourse. Commonly known as the “pleasure neurotransmitter”, it has been shown to not only be involved in reward and motivation, but also with movement and learning as well. The main idea behind schizophrenia’s cause, termed the “dopamine hypothesis”, is that hyperactivity of the inhibitory dopamine receptors (the neighboring neuron’s lock that dopamine binds to) leads to positive symptoms and hypoactivity of the excitatory dopamine receptors leads to the negative symptoms (Davis et al., 1991, as cited in Howes & Kapur, 2009). Although this is the main hypothesis, the disorder itself is not well understood. The main evidence behind this hypothesis is that medications affecting the dopaminergic levels in the brain tend to work for schizophrenia’s positive symptoms.
WORKING MEMORY IN SCHIZOPHRENIA
Working memory is one of the cognitive functions that is impaired in schizophrenia, with little explanation as to how or why. Although some research indicates that dopaminergic regions in the brain are correlated with working memory function (Landau et al., 2009), there is still no effect of antipsychotic medications helping to repair schizophrenia’s deficit in immediate working memory (Mori et al., 2004). Perhaps the mindset of the individual is also involved? In a recent study by Sanchez-Torres et al. (2022), researchers assessed the cognitive abilities of schizophrenic individuals along with their symptomatology. They saw that higher scores on the Frankfurt Complaint Questionnaire, a subjective assessment of schizophrenic and psychotic symptoms, predicted lower performance in working memory neuropsychological assessments. No matter the cause, working memory impairment in schizophrenic individuals is a real problem that needs to be addressed in order to further make an impact on this population. In the next few paragraphs, we will be going over recent research done on solidifying the working memory deficits in schizophrenia patients.
Trail Making Task
A paradigm of working memory is the Trail Making Task, which is split into two parts (Part A and Part B). In Part B, participants are given a piece of paper with circles, each with either a number from 1-12 or a letter from A-L, making 24 circles in total. Each participant has to make a trail with their pencil (without removing it from the paper) to a sequence that goes 1-A-2-B-3-C, etc., and the assessment is shown as the time it takes to complete the task. With higher time being representative of impairment, the task indicates working memory, because you must keep track of the past two circles in your sequence in order to make a correct move onto the next one.
When schizophrenic individuals complete this task compared to controls, Zanelli et al. (2022) found that patients with schizophrenia exhibited lower working memory performance that only got worse over time.
Updating and Maintenance Paradigm
Another paradigm, which Gotra, Keedy, and Hill (2022) claimed to be an “Updating and Maintenance Paradigm” is another indicator of working memory. In this experiment, a participant is shown a target item (i.e., purple square) in a specific location on a grid, followed by a delay from 1000-8000 ms. Then, they are shown a comparison item (i.e., blue square) located somewhere on the grid, without the purple square present. Participants must indicate whether the comparison item was in the same location as the target item, and their accuracy is a measure of their working memory capability.
As delay increased during this paradigm, performance decreased for individuals with schizophrenia spectrum disorder compared to controls, and an even greater decline when the delay was higher. These results concluded that working memory is short-lived and subject to interference in individuals with schizophrenia.
WHY THIS MATTERS
As discussed before, working memory is essential for day-to-day functioning. Given that the onset of schizophrenia begins during college years (ages 18-25), research can further ensure that working memory can be repaired in the schizophrenic individuals to aid their academic success and help them achieve their goals. Capability to maintain a professional or educational life can be difficult for individuals with schizophrenia, as their ability to communicate and problem-solve is impaired. In a recent study by Dickson et al. (2020), schizophrenic individuals are less likely to complete secondary or higher education, and overall have lower academic achievement.
Before we can improve the lives of these individuals, more research needs to be done on the different types of learning and memory, especially ones that can be applicable to real-world and educational environments. To add on, more studies should be done on the learning and memory for human subjects currently experiencing symptoms of psychosis. Although the ethical and conventional approaches to this are limited, it would be beneficial to aid schizophrenic patients during episodes instead of only when they are medicated. While considering medication, more research needs to be done on varying antipsychotics and their effects on cognition, given the conflicting literature. With this research can we establish other medication routes that will improve the cognitive deficits in schizophrenia? Until all of these gaps are filled in the field, we cannot create the difference that we strive to make in individuals with schizophrenia.
REFERENCES
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596
Davis, K. L., Kahn, R. S., Ko, G., & Davidson, M. (1991). Dopamine in schizophrenia: A review and reconceptualization. The American Journal of Psychiatry, 148(11), 1474–1486. https://doi.org/10.1176/ajp.148.11.1474
Dickson, H., Hedges, E. P., Ma, S. Y., Cullen, A. E., MacCabe, J. H., Kempton, M. J., Downs, J., & Laurens, K. R. (2020). Academic achievement and schizophrenia: a systematic meta-analysis. Psychological medicine, 50(12), 1949–1965. https://doi.org/10.1017/S0033291720002354
Gotra, M. Y., Keedy, S. K., & Hill, S. K. (2022). Interactive effects of maintenance decay and interference on working memory updating in schizophrenia. Schizophrenia Research, 239, 103-110. https://doi.org/10.1016/j.schres.2021.11.028
Howes, O. D., & Kapur, S. (2009). The dopamine hypothesis of schizophrenia: version III--the final common pathway. Schizophrenia Bulletin, 35(3), 549–562. https://doi.org/10.1093/schbul/sbp006
Landau, S. M., Lal, R., O'Neil, J. P., Baker, S., & Jagust, W. J. (2009). Striatal dopamine and working memory. Cerebral Cortex, 19(2), 445-454. https://doi.org/10.1093/cercor/bhn095
Mori, K., Nagao, M., Yamashita, H., Morinobu, S., & Yamawaki, S. (2004, July). Effect of switching to atypical antipsychotics on memory in patients with chronic schizophrenia. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 28(4), 659–665. https://doi.org/10.1016/j.pnpbp.2004.01.019
Sánchez-Torres, A. M., Moreno-Izco, L., Gil-Berrozpe, G., Lorente-Omeñaca, R., Zandio, M., Zarzuela, A., Peralta, V., & Cuesta, M. J. (2022). Assessment of cognitive impairment in psychosis spectrum disorders through self-reported and interview-based measures. European Archives of Psychiatry and Clinical Neuroscience, 272(7), 1183-1192. https://doi.org/10.1007/s00406-022-01399-4
Zanelli, J., Reichenberg, A., Sandin, S., Morgan, C., Dazzan, P., Pilecka, I., Marques, T. R., Morgan, K., Young, A. H., & Mollon, J. (2022). Dynamic and static cognitive deficits in schizophrenia and bipolar disorder after the first episode. Schizophrenia Bulletin, 48(3), 590-598. https://doi.org/10.1093/schbul/sbab150
Commenti