Scary voices at night? Sign of mental disorders like schizophrenia, not ghosts

A recent study provides fresh insight into why certain individuals perceive auditory hallucinations in the absence of external sounds.

The researchers have identified two potential brain process failures contributing to auditory hallucinations in mental disorders like schizophrenia: malfunctioning corollary discharge and overly active efference copy.

The study, involving patients’ electroencephalogram (EEG), shows that these flaws may prevent the brain from properly identifying self-generated sounds, offering a new direction for treatment.

Schizophrenia auditory hallucinations

Auditory hallucinations are likely the result of abnormalities in two brain processes: a “broken” corollary discharge that fails to suppress self-generated sounds and a “noisy” efference copy that makes the brain hear these sounds more intensely than it should.

That is the conclusion of a new study published on October 3 in the open-access journal PLOS Biology by Xing Tian of New York University Shanghai, China, and colleagues.

Patients with certain mental disorders, including schizophrenia , often hear voices in the absence of sound.

Patients may fail to distinguish between their thoughts and external voices, reducing their ability to recognize thoughts as self-generated.

In the new study, researchers carried out EEG experiments measuring the brain waves of twenty patients diagnosed with schizophrenia with auditory hallucinations and twenty patients diagnosed with schizophrenia who had never experienced such hallucinations.

Reason for voices

In general, when people prepare to speak, their brains send a signal known as “corollary discharge” that suppresses the sound of their voice.

However, the new study showed that when patients with auditory hallucinations were preparing to speak a syllable, their brains not only failed to suppress these internal sounds but had an enhanced “efference copy” response to internal sounds other than the planned syllable.

The authors conclude that impairments in these two processes likely contribute to auditory hallucinations and that targeting them in the future could lead to new treatments for such hallucinations.

The authors add, “People who suffer from auditory hallucinations can ‘hear’ sounds without external stimuli.”

The new study suggests that impaired functional connections between the brain’s motor and auditory systems mediate the loss of the ability to distinguish fancy from reality.

Schizophrenia links with abnormal dopamine

Recently, researchers found strong evidence to suggest that abnormal dopamine signaling can cause schizophrenia.

In their previous research, a team of scientists had shown that low levels of maternal vitamin D increase the risk of schizophrenia in offspring.

The same University of Queensland’s Brain Institute team dug deeper into their previously published work. It used molecular imaging technology to confirm the role played by a mother’s vitamin D levels in developing the baby’s dopamine-producing brain cells.

In their new study, the scientists created dopamine-like neurons to replicate the cell differentiation process during an embryo’s development. Cell differentiation is how dividing cells change their functional or phenotypical type.

The neurons were cultured with and without the hormone calcitriol, the active form of Vitamin D, and bind to its receptor in the cell’s nucleus.

The researchers discovered that not only cell differentiation but the neuron structure was affected by vitamin D.

The study’s results open new avenues for research into the connection between vitamin D and dopamine-neuron function.