Objective: Detecting brain abnormalities in clinical high-risk populations before the onset of psychosis is important for tracking pathological pathways and for identifying possible intervention strategies that may impede or prevent the onset of psychotic disorders. Co-occurring cellular and extracellular white matter alterations have previously been implicated after a first psychotic episode. The authors investigated whether or not cellular and extracellular alterations are already present in a predominantly medication-naive cohort of clinical high-risk individuals experiencing attenuated psychotic symptoms. Methods: Fifty individuals at clinical high risk, of whom 40 were never medicated, were compared with 50 healthy control subjects, group-matched for age, gender, and parental socioeconomic status. 3-T multishell diffusion MRI data were obtained to estimate free-water imaging white matter measures, including fractional anisotropy of cellular tissue (FA(T)) and the volume fraction of extracellular free water (FW). Results: Significantly lower FA(T) was observed in the clinical high-risk group compared with the healthy control group, but no statistically significant FW alterations were observed between groups. Lower FA(T) in the clinical high-risk group was significantly associated with a decline in Global Assessment of Functioning Scale (GAF) score compared with highest GAF score in the previous 12 months. Conclusions: Cellular but not extracellular alterations characterized the clinical high-risk group, especially in those who experienced a decline in functioning. These cellular changes suggest an early deficit that possibly reflects a predisposition to develop attenuated psychotic symptoms. In contrast, extracellular alterations were not observed in this clinical high-risk sample, suggesting that previously reported extracellular abnormalities may reflect an acute response to psychosis, which plays a more prominent role closer to or at onset of psychosis.
Objective: This study tested for differences of white matter integrity between treated and never-treated long-term schizophrenia patients, matched on illness duration, and for differential changes in relation to age in these two groups relative to healthy comparison subjects. Method: This cross-sectional diffusion tensor imaging study included 31 never-treated and 46 matched antipsychotic-treated patients with long-term schizophrenia and 58 healthy comparison subjects. Fractional anisotropy measures of white matter tracts were extracted and compared. Linear regression analysis was used to explore the association between age and fractional anisotropy among the three groups. Results: Fractional anisotropy significantly differed among the three groups in 14 of 20 white matter tracts defined in the Johns Hopkins University white matter template. Never-treated patients displayed greater reduction of fractional anisotropy than antipsychotic-treated patients in the left anterior thalamic radiation, the left cingulum-hippocampus pathway, the splenium and genu of the corpus callosum, and the left superior longitudinal fasciculus, and greater fractional anisotropy in the right uncinate fasciculus. Both patient groups showed multiple reductions relative to healthy comparison subjects. Never-treated patients showed an accelerated and clinically relevant age-related reduction of fractional anisotropy in the genu of the corpus callosum. Conclusions: These psychoradiological findings provide insight into the regional distribution of white matter deficits in the years after illness onset in long-term schizophrenia. Findings of greater impairments in never-treated patients, and a greater age-related reduction in the genu of the corpus callosum in these patients, suggest that long-term antipsychotic treatment does not adversely affect white matter tracts over the longer-term course of illness and may confer benefits.
Objective: Stress is a strong risk factor for major depressive disorder, while sensitization tostress inremittedindividualsplays a key role in depression recurrence. The present study explored the state-independent (trait) and dependent (state) neural responses to psychosocial stress in major depressive disorder. Method: Thirty-sixpatients withmedication-naivefirst-episode current depression, 33 patients with remitted depression, and 36 demographically matched healthy control participants were administered the Montreal Imaging Stress Task during functional MRI. One-way analyses of variance were used to assess differences in stress responses in the three groups. Results: Both currently depressed and remitted patients exhibitedhigher stress levels and cortisol responses thancontrol subjects. Compared with control subjects, both depressed and remitted patients exhibited reduced activation in the ventromedial prefrontal cortex and increased activation in the precuneus. The stress-induced ventromedial prefrontal cortex activation changes negatively correlated with cortisol increases in all three groups. Additional increased activations were found in the dorsolateral prefrontal cortex and bilateral striatum in remitted patients compared with control subjects, and activation in these regions correlated inversely with depressive symptoms in the remitted group. Conclusions: These findings provide novel evidence regarding the trait and state markers of depression on neural responses to psychosocial stress. Regional activation changes in the ventromedial prefrontal cortex and precuneus may reflect the trait markers of depression. Hyperactivation in the dorsolateral prefrontal cortex and striatum may represent a state-dependent compensatory mechanism during depression remission.