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Background: The integrity and function of catecholamine neurotransmitter systems can be assessed using neuromelanin‐sensitive MRI (NM‐MRI). The relevance of this method to neurodegenerative and psychiatric disorders is becoming increasingly evident, and it has potential as a clinical biomarker. Purpose: To support future application of NM‐MRI as a clinical biomarker by defining the normative range of NM‐MRI signal and volume metrics in cognitively normal older adults. Study Type: Prospective. Population: A total of 152 cognitively normal older adults aged 53–86 years old, including 41 participants who had follow‐up NM‐MRI data collected 9–16 months later. Field Strength/Sequence: A 3.0 T; NM‐MRI turbo spin echo and T1‐weighted magnetization‐prepared rapid acquisition with gradient echo sequences. Assessment: NM‐MRI images were processed to yield summary measures of volume and signal (contrast‐to‐noise ratio, CNR) for the substantia nigra (SN) and locus coeruleus (LC) using a recently developed software employing a fully automated algorithm. Change in these metrics over time was also assessed. Statistical Tests: Mean and standard deviation of NM‐MRI metrics were calculated; change over time was tested for significance using 1‐sample t‐tests. P values < 0.05 were considered statistically significant. Results: At baseline SN signal (CNR) was 10.02% (left) and 10.28% (right) and LC signal was 24.71% (left) and 20.42% (right). Baseline SN volume was 576 mm3 (left) and 540 mm3 (right) and LC volume was 6.31 mm3 (left) and 6.30 mm3 (right). The only NM‐MRI metric showing significant change was a decrease in left SN volume (t40 = −2.57, P = 0.014). Data Conclusion: We report normative values for NM‐MRI signal and volume in the SN and LC of cognitively normal older adults and explore their change over time. These values may help future efforts to use NM‐MRI as a clinical biomarker by facilitating identification of patients with extreme NM‐MRI values. Level of Evidence: 2. Technical Efficacy Stage: 1. [ABSTRACT FROM AUTHOR]

Background: Dysfunctional reward processing is present in individuals with schizophrenia-spectrum disorders (SSD) and may confer vulnerability to addiction. Our objective was to identify a deficit in patients with SSD on response to rewarding stimuli and determine whether this deficit predicts cannabis use. Methods: We divided a group of patients with SSD and nonpsychotic controls into cannabis users and nonusers. Response to emotional and cannabis-associated visual stimuli was assessed using self-report, event-related potentials (using the late positive potential [LPP]), facial electromyography and skin-conductance response. Results: Our sample comprised 35 patients with SSD and 35 nonpsychotic controls. Compared with controls, the patients with SSD showed blunted LPP response to pleasant stimuli (p = 0.003). Across measures, cannabis-using controls showed greater response to pleasant stimuli than to cannabis stimuli whereas cannabis-using patients showed little bias toward pleasant stimuli. Reduced LPP response to pleasant stimuli was predictive of more frequent subsequent cannabis use (P =-0.24, p = 0.034). Limitations: It is not clear if the deficit associated with cannabis use is specific to rewarding stimuli or nonspecific to any kind of emotionally salient stimuli. Conclusion: The LPP captures a reward processing deficit in patients with SSD and shows potential as a biomarker for identifying patients at risk of heavy cannabis use., Introduction There has been rapid expansion of interest in reward processing deficits in individuals with schizophrenia-spectrum disorders (SSD). (1,2) As the nature of the reward deficits is better defined, a [...]

BACKGROUND: Dysfunctional reward processing is present in individuals with schizophrenia-spectrum disorders (SSD) and may confer vulnerability to addiction. Our objective was to identify a deficit in patients with SSD on response to rewarding stimuli and determine whether this deficit predicts cannabis use. METHODS: We divided a group of patients with SSD and nonpsychotic controls into cannabis users and nonusers. Response to emotional and cannabis-associated visual stimuli was assessed using self-report, event-related potentials (using the late positive potential [LPP]), facial electromyography and skin-conductance response. RESULTS: Our sample comprised 35 patients with SSD and 35 nonpsychotic controls. Compared with controls, the patients with SSD showed blunted LPP response to pleasant stimuli (p = 0.003). Across measures, cannabis-using controls showed greater response to pleasant stimuli than to cannabis stimuli whereas cannabis-using patients showed little bias toward pleasant stimuli. Reduced LPP response to pleasant stimuli was predictive of more frequent subsequent cannabis use (β = -0.24, p = 0.034). LIMITATIONS: It is not clear if the deficit associated with cannabis use is specific to rewarding stimuli or nonspecific to any kind of emotionally salient stimuli. CONCLUSION: The LPP captures a reward-processing deficit in patients with SSD and shows potential as a biomarker for identifying patients at risk of heavy cannabis use. [ABSTRACT FROM AUTHOR]