05 01 2016
Psychotic disorders like schizophrenia have long been established to have accompanying changes in brain structure and function. Hippocampal volume loss is the most significant and consistent of such changes. Medial temporal lobe seems to be the area where most changes occur. Volume reductions seen in unaffected relatives make us support the idea of heritable phenotypes.
Youth who are classified as high risk, who later convert to psychosis ,also have (North American Prodrome Longitudinal Study consortium , 2015 ) accelerated gray matter loss in frontal cortex compared with non- converters and healthy comparators. what about those who experience some psychotic spectrum experiences?
Do non-help seeking youth who experience psychotic spectrum symptoms have structural changes in brain? Transition to psychosis in this group will be lower than the high risk groups. Large imaging studies haven’t addressed this question so far.Philadelphia Neu- rodevelopmental Cohort (PNC) is trying to answer this question. Theodore D. Satterthwaite and team from University of Pennsylvania Perelman School of Medicine report the findings of their study.
The cohort comprises 1429 individuals ( mean age around 15) . PS symptoms were present in 408 participants. This was assessed using the GOASSESS interview ( combination of questions from K SADS, PRIME, Scale of prodromal symptoms).Analysis is based on the final sample of 391 youth with Psychotic spectrum features (PS group) and 400 Typically Developing youth (TD group) 8 to 22 years old.
Youth with Psychotic spectrum symptoms had reduced intra cranial volume as compared with typically developing youth. They showed marked reduction in gray matter volume. Difference was more in older participants. Volume loss was more marked in medial temporal lobe.Greater severity of PS symptoms was associated with volume reduction in bilateral medial temporal lobe.
It is important to note that this is a community based study and participants were non help seeking. Still, the changes mirrors that seen in both adults with clinically diagnosed psychotic disorders and youth at clinical risk. One could say that regions affected are part of the default mode network. (large functional network critical for internally directed attention, theory of mind, social cognition, and memory).
Adolescents with psychotic spectrum experiences have identifiable brain structural changes. These are similar to those observed in established psychotic disorders.imaging phenotypes are important in evaluating risk of conversion to psychosis. This may ,in future, help in early identification and intervention.
summary of the article :
Structural Brain Abnormalities in Youth With Psychosis Spectrum Symptoms. Satterthwaite TD, Wolf DH, Calkins ME, Vandekar SN, Erus G, Ruparel K, Roalf DR, Linn KA, Elliott MA, Moore TM, Hakonarson H, Shinohara RT, Davatzikos C, Gur RC, Gur RE.JAMA Psychiatry. 2016 May 1;73(5):515-24.