Nav: Home

Schizophrenia: Adolescence is the game-changer

June 17, 2019

Schizophrenia causes hallucinations and memory or cognition problems inter alia. This psychiatric illness affects 0.5% of the general population, and it may be related to genetic abnormalities of chromosome 22, known as 22q11 deletion syndrome. However, not everyone who has the syndrome necessarily develops psychotic symptoms. So, what triggers the illness? Researchers at the University of Geneva (UNIGE), Switzerland, have provided an initial answer after observing and analysing several years of patients with deletion syndrome. The scientists found that the size of the hippocampus, the area of the brain responsible for memory and emotions, was smaller than normal but followed the same developmental curve as in healthy subjects. Yet, when the first psychotic symptoms appear - generally in adolescence - the hippocampus atrophies dramatically. The results, which you can read all about in the journal Molecular Psychiatry, open up new avenues for understanding the causes of schizophrenia.

22q11 deletion syndrome is a neurogenetic disorder that targets chromosome 22. Thirty percent of people affected by the syndrome end up developing psychotic symptoms specific to schizophrenia, such as auditory hallucinations, memory problems, disorders affecting their perception of reality, and difficulties in social interactions characterised by strong paranoia. "It's now known that schizophrenia is linked to the hippocampus, a complex area of the brain that carries out a vast amount of processes simultaneously linked to memory, imagination and the emotions," explains Stephan Eliez, professor in the Department of Psychiatry in UNIGE's Faculty of Medicine. Recent studies have shown that also people suffering from deletion syndrome have a smaller than average hippocampus. "That's why we studied the development of this structure in detail," continues the UNIGE researcher, "so we could understand why some people affected by deletion syndrome eventually develop psychotic symptoms, while others don't."

18-year study investigating the development of the hippocampus

The Geneva team has been following 275 patients aged 6 to 35 years for 18 years: a control groups of 135 individuals - i.e. individuals without genetic problems - and 140 people with deletion syndrome, including 53 with moderate to severe psychotic symptoms. "They underwent an MRI every three years so that we could observe their brain development," says Valentina Mancini, a researcher in UNIGE's Department of Psychiatry. "This has helped us create a statistical model that measures and compares the development of the hippocampus in both groups of patients." It was discovered that the hippocampus of the group affected by deletion syndrome, although smaller from the beginning, followed a growth curve identical to that of the control group. "This meant that we could hypothesise that the smaller size of the hippocampus originates in utero during its development in the womb." The UNIGE scientists also observed the subfields of the hippocampus in detail, discovering that one of them - called CA3 - was not affected by the decrease in size. "This subfield plays a crucial role in the work of memorisation and seems stronger than the other sub-parts," adds professor Eliez.

Adolescence: the period that counts the most

The researchers then compared the developmental curves of the hippocampus in people with deletion syndrome but no psychotic symptoms with those who developed psychotic symptoms. "There's no doubt about our results: around the age of 17 or 18, people with schizophrenic symptoms experience a drastic atrophy in the size of their hippocampus, and especially in the CA3 area, despite CA3 had initially managed to develop normally, unlike the other subfields," says Mancini. But why?

The researchers don't have yet a precise answer that could explain the drastic drop in the development of this vital brain structure. But their hypotheses are geared towards environmental factors, such as stress or neuronal inflammation. "The hippocampus of individuals with deletion syndrome is smaller; this means it has to compensate for its size through hyperactivity. In the event of a huge stress factor, especially during the critical period of adolescence, this hyperactivity might lead to a significant rise in glutamate that 'poisons' the hippocampus and causes its atrophy," explains Mancini. The psychotic symptoms may result from this hyper-compensation, which ends up destroying the hippocampus.

Act before the critical period

The study suggests the following hypothesis: the small size of the hippocampus in patients with 22q11 deletion syndrome is defined in the mother's womb, probably due to poor vascularisation. However, a "second hit" later in development might determine the further hippocampal atrophy and the emergence of psychotic symptoms. As the critical period for schizophrenia is adolescence, the Genevan team is now working on the possibility of preventing the atrophy of the hippocampus in order to preserve its functions.
-end-


Université de Genève

Related Schizophrenia Articles:

Unlocking schizophrenia
New research, led by Prof. LIU Bing and Prof. JIANG Tianzi from the Institute of Automation of the Chinese Academy of Sciences and their collaborators have recently developed a novel imaging marker that may help in the personalized medicine of psychiatric disorders.
Researchers discover second type of schizophrenia
In a study of more than 300 patients from three continents, over one third had brains that looked similar to healthy people.
New clues into the genetic origins of schizophrenia
The first genetic analysis of schizophrenia in an ancestral African population, the South African Xhosa, appears in the Jan.
Dietary supplement may help with schizophrenia
A dietary supplement, sarcosine, may help with schizophrenia as part of a holistic approach complementing antipsychotic medication, according to a UCL researcher.
Schizophrenia: Adolescence is the game-changer
Schizophrenia may be related to the deletion syndrome. However, not everyone who has the syndrome necessarily develops psychotic symptoms.
Study suggests overdiagnosis of schizophrenia
In a small study of patients referred to the Johns Hopkins Early Psychosis Intervention Clinic (EPIC), Johns Hopkins Medicine researchers report that about half the people referred to the clinic with a schizophrenia diagnosis didn't actually have schizophrenia.
The ways of wisdom in schizophrenia
Researchers at UC San Diego School of Medicine report that persons with schizophrenia scored lower on a wisdom assessment than non-psychiatric comparison participants, but that there was considerable variability in levels of wisdom, and those with higher scores displayed fewer psychotic symptoms.
Recognizing the uniqueness of different individuals with schizophrenia
Individuals diagnosed with schizophrenia differ greatly from one another. Researchers from Radboud university medical center, along with colleagues from England and Norway, have demonstrated that very few identical brain differences are shared amongst different patients.
Resynchronizing neurons to erase schizophrenia
Today, a decisive step in understanding schizophrenia has been taken.
Genetics researchers close in on schizophrenia
Researchers at the MRC Centre for Neuropsychiatric Genetics and Genomics at Cardiff University have discovered 50 new gene regions that increase the risk of developing schizophrenia.
More Schizophrenia News and Schizophrenia Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.