Negative symptoms of schizophrenia linked with an overactive brain
The search for well-targeted treatment for schizophrenia continues. Researchers have conducted several studies, and some have uncovered insights that could help with treatment procedures. Interestingly, a new study has shed more light yet on the topic.
New research shows that over-activity in the hippocampus of the brain is linked with certain schizophrenia symptoms, which could help in developing more targeted treatments.
The researchers found that faulty inhibitory neurotransmitters and hyperactivity in the hippocampus disrupt associative learning, which manifests as fear conditioning. Disrupted associative learning is linked with the negative symptoms of schizophrenia, such as lethargy, lack of emotion or motivation, social withdrawal, and disrupted reward processing. However, these same occurrences (faulty inhibitory neurotransmitters and hippocampal hyperactivity) do not lead to hallucinations and impaired memory.
The study conducted by University of Nottingham researchers has been published in eNeuro.
To understand the entire pathway, we need to review the symptoms of schizophrenia and the neurotransmitters in question.
Positive and negative symptoms of schizophrenia
Schizophrenia is a serious mental illness that affects how a person thinks, behaves, and feels. A person with schizophrenia can seem dissociated from their world -- like they have lost touch with reality. Hallucinations aren't uncommon.
Some people consider schizophrenia the worse disease to affect humankind. At every point in time, the NHS is treating about 220,000 schizophrenia patients in the UK.
Schizophrenia can manifest in three ways:
- Positive symptoms, including hallucinations and delusions
- Negative symptoms, including apathy, lethargy, disrupted reward processing, and social withdrawal
- Cognitive symptoms, including impaired memory.
Any or all of the symptoms can occur in a schizophrenia patient at the same time.
Now, how does all of that relate to brain activity?
Neurotransmitters and schizophrenia
Neurons in the brain work and interpret stimuli by releasing chemical substances known as neurotransmitters.
Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in the hippocampus crucial to restraining neural activity. That is, it prevents the neurons from always releasing neurotransmitters and responding to irrelevant stimuli. When GABA becomes deficient, irrelevant stimuli might not be filtered out since the neurons get too hyperactive.
Notably, past studies have discovered that the ability to filter out irrelevant information is impaired in schizophrenia patients. This is a key process that causes hallucinations (the positive symptoms of schizophrenia).
However, the research found no evidence that faulty neurotransmission inhibition causes any of the positive or cognitive symptoms of schizophrenia. Instead, they found that "it may contribute to some of the negative symptoms of schizophrenia, disrupting associative learning in the form of conditioned fear."
The study was carried out on rats.
The implications of the research
The research findings might seem paradoxical. One may think that the faulty neurotransmission in the hippocampus would cause hallucinations (the positive symptoms). But that doesn't seem to be the case. Instead, the study opens up new information on the negative symptoms of schizophrenia.
Hence, the study has relevant implications for developing targeted treatments for the negative symptoms of schizophrenia. For example, one way to treat the negative symptoms would likely involve reducing the over-activity in the hippocampus.