Schizophrenia: Synaptic dysfunction plays key role

 

• Schizophrenia is an often misunderstood chronic mental illness that causes psychosis.
• The biological mechanism of schizophrenia is poorly understood, and current treatments have significant limitations.
• According to a new study, the imbalance of nerve cell activity responsible for the condition and its associated symptoms may result from the body trying to rebalance excitatory and inhibitory functions.

Schizophrenia is a debilitating, complicated mental disorder that affects 20 millionTrusted Source people globally.

It is a psychotic condition. People with schizophrenia have a unique combination of symptoms or experiences, which may include :

• feeling disconnected
• hallucinations
• hearing voices
• delusions
• confused thinking or speech

People can manage the condition with medicine and psychosocial therapy. However, relapses can occur, affecting a person’s work or education.

Despite treatment, people with schizophrenia are 2-3 times more likely to die early than the general population. PreventableTrusted Source diseases, such as cardiovascular disease, respiratory disease, and infections, are often responsible for these deaths.

The exact cause of schizophrenia is unknown. However, several factors, such as stress, drugs, genetic inheritance, and differences in brain chemistry, can increase the risk of developing this condition.

Schizophrenia and brain chemistry

Researchers have long suspected differences in brain chemistry to be the cause of schizophrenia. People with the condition typically have differences in their neurotransmitters — chemicals that control communication within the brain. StudiesTrusted Source have shown that people with schizophrenia have neurotransmitters that are either overactive or underactive.

Dr. Rick Adams, a Research Fellow at the Centre for Medical Image Computing at University College London (UCL), U.K., explained to Medical News Today that there is an enormous amount of indirect evidence that synaptic gain decreases in schizophrenia. This means that excitatory neurons have a reduced ability to stimulate one another.

It was this implicit theory that led to the recent study looking into synaptic disruption in schizophrenia. The paper appears as a Journal pre-proof in Biological Psychiatry.

In the study, Dr. Adams and colleagues used computational modeling of electroencephalography (EEG) to record brain activity and measure overall synaptic gain. They collected EEG data from 272 participants, which comprised 107 with diagnosed schizophrenia, 57 of their relatives, and 108 control participants.

Study co-author L.Elliot Hong, MD, Professor of Psychiatry at the University of Maryland School of Medicine, told MNT: “Participants were recruited from the Greater Baltimore area, and the racial proportions in the sample should be roughly consistent with those in this area. This area is racially diverse.”

Each participant underwent three EEGs and a resting functional magnetic resonance imaging (fMRI)Trusted Source. The researchers took EEG measurements at rest and when using two different auditory stimuli:

• mismatch negativity, where a rogue or different pitched sound or other stimulus interrupts a steady, repetitive noise
• 40Hz auditory steady-state response, where the stimulus is a frequent click-sound

How synaptic dysfunction links to symptoms

Dynamic causal modeling of each of the EEG experiments and fMRI data showed changes in the group of people who had received a diagnosis of schizophrenia.

The altered brain waves in those with diagnosed schizophrenia occurred due to a loss of synaptic gain, or excitability. The hallucinations and other symptoms of schizophrenia were, however, associated with loss of neural inhibition.

“This might mean that the loss of excitation comes first, then the brain tries to compensate for this by reducing inhibition, but then this leads to hallucinations,” said Dr. Adams.

He went further to say, “Imagine you are trying to listen to someone speaking on the radio, but the signal is very weak: if you turn the volume right up, the speech is louder, but so is all the static and background noise, and so you may mistake some of this noise for actual speech.”

Despite a great deal of pharmaceutical investment, there is still not a targetted drug to treat schizophrenia by understanding the biology of the disease and identifying the receptors and processes involved.

Dr. Adams believes that “if future studies can establish this, it means we should be able to give treatments that change excitatory or inhibitory function at the right time and to the right people.”

Bipolar and schizophrenia symptoms

Bipolar disorder and schizophrenia are psychiatric conditions that have some common traits, but also key differences. Bipolar disorder causes shifts in mood, energy levels, and thinking. Schizophrenia causes a person to appear to lose touch with reality.

People with bipolar disorder may experience episodes of mania and depression, often separated by periods of relative stability.

Individuals with schizophrenia experience symptoms of psychosis, such as hallucinations or delusions. Some people with bipolar disorder also experience psychotic symptoms.

Because of some overlap in symptoms, getting the right diagnosis can be challenging. Also, a person can have bothTrusted Source schizophrenia and bipolar disorder, which can complicate diagnosis.

Some people have schizoaffective disorder, which involves a combination of schizophrenia symptoms and those of a mood disorder.

In this article, we look at the similarities and differences between bipolar disorder and schizophrenia. We also discuss methods of diagnosis and treatment options.

Source: Medical News Today