Glutamate levels across deep brain structures in patients with a psychotic disorder and its relation with cognitive functioning

Abstract

ABSTRACTPatients with psychotic disorders often show prominent cognitive impairment. Glutamate seems to play a prominent role, but knowledge on its role in deep gray matter regions is limited and previous studies have yielded heterogeneous results. The aim was to evaluate glutamate levels within deep gray matter structures in patients with a psychotic disorder in relation to cognitive functioning, using advanced spectroscopic acquisition, reconstruction and post-processing techniques. A 7 tesla MRI scanner combined with a unique lipid suppression coil and subject specific water signal suppression pulses were used to acquire high-resolution magnetic resonance spectroscopic imaging data. Anatomical scans were used to perform tissue fraction correction and registration to a standard brain for group comparison in specifically delineated brain regions. The brief assessment of cognition in schizophrenia was used to evaluate cognitive status. Average glutamate levels across deep gray matter structures (i.e. caudate, pallidum, putamen, and thalamus) in patients with a psychotic disorder (n=16, 4 females) were lower compared to healthy controls (n=23, 7 females). Stratified analyses showed lower glutamate levels in the caudate and putamen but not in the pallidum or thalamus. Average glutamate levels across deep gray matter structures were positively correlated with cognition, particularly to psychomotor speed. We find reduced glutamate levels across deep brain structures such as the caudate and putamen in patients with a psychotic disorder that are linked to psychomotor speed. Our results underscore the potential role of detailed in vivo glutamate assessments to understand cognitive deficits in patients with psychotic disorders.