The temporal lobe thickness of first-degree relatives of people with schizophrenia shows a significant association with verbal learning, according to a study recently published in Schizophrenia Research.
Study researchers included 62 unaffected siblings and parents of adults with schizophrenia, as well as 70 healthy controls. Verbal memory was assessed via a comprehensive set of tests for neurocognition, and MRI (magnetic resonance imaging) scans were conducted to determine cortical thickness. To make these assessments mathematically operable, test results were represented by a derived verbal learning factor, and MRI results were assigned a variable by summing and averaging cortical thickness across the temporal lobe and adjusting for age and sex.
Group and verbal learning showed a strong association with thickness of the temporal lobe (P =.01). Verbal learning also correlated with temporal lobe thickness (P =.02) without the inclusion of group. Neither showed statistical significance in relation to frontal lobe cortical thickness. A post-hoc analysis indicated that temporal lobe thickness and verbal learning factor also showed significant Pearson correlations (r =.41, P =.001) within first-degree relatives.
The frontal and temporal lobes of both people with schizophrenia and their first-degree relatives who do not have the disorder have displayed cortical thinning, and it has been demonstrated that such relatives also demonstrate reduced neurocognitive performance. The study researchers predicted a positive relationship between cortical thinning and verbal memory impairment in unaffected first-degree relatives of people with schizophrenia.
The researchers conclude that “cortical thickness in the temporal cortex may represent a structural correlate for encoding verbal information in unaffected relatives of individuals with schizophrenia.”
Fernandez VG, Asarnow R, Narr KL, et al. Temporal lobe thickness and verbal memory in first-degree relatives of individuals with schizophrenia [published online February 27, 2018]. Schizophr Res. doi: 10.1016/j.schres.2018.02.038