The reward system regulates the processes that motivate people to pursue evolutionary beneficial stimuli. Effective functioning of the reward system can protect against the development of anhedonia. In the daily life, the reward system can be expressed as the dynamic interplay of positive affect (liking), reward anticipation (wanting), and active behavior (engaging). Applying network analysis to daily life experience data allows us to identify such reward dynamics and use them to predict future depressive symptoms.

We investigated whether at baseline (i) higher network positive affect in-strength, reflecting how strongly positive affect is influenced by other components and hence the level of anhedonia, and (ii) higher network connectivity, reflecting overall functioning of the reward system, are associated with fewer depressive symptoms on follow-up.

We used data from 43 participants with mild depressive symptoms from the SMARTSCAN study. The dynamic interplay between momentary positive affect, reward anticipation, and active behavior was assessed with individual vector-autoregressive models and the network analysis. Network positive affect in-strength and connectivity indices were used to predict a six-month depressive symptoms trajectory.

Reward systems networks vary greatly between individuals. On the group level, higher positive affect in-strength (Beta=-3.66, p=0.05) and network connectivity (Beta=-4.06, p=0.03) at baseline were associated with fewer symptoms at follow-up.

Higher influences of reward anticipation and active behavior on positive affect and stronger connections between reward cycle components are associated with fewer future symptoms, suggesting the importance of daily life reward cycle dynamics in depression.

No significant relationships.

It is well-known that attention deficit hyperactivity disorder (ADHD) is associated with changes in the dopaminergic system. However, the relationship between central dopaminergic tone and the blood oxygen level-dependent (BOLD) signal during receipt of rewards and penalties in the corticostriatal pathway in adults with ADHD is unclear.

Single-photon emission computed tomography with [99mTC]TRODAT-1 was used to assess striatal dopamine transporter (DAT) availability. Event-related functional magnetic resonance imaging was conducted on subjects performing the Iowa Gambling Test.

DAT availability was found to be associated with the BOLD response, which was a covariate of monetary loss, in the medial prefrontal cortex (r = 0.55, P = .03), right ventral striatum (r = 0.69, P = .003), and right orbital frontal cortex (r = 0.53, P = .03) in adults with ADHD. However, a similar correlation was not found in the controls.

The results confirmed that dopaminergic tone may play a different role in the penalty-elicited response of adults with ADHD. It is plausible that a lower neuro-threshold accompanied by insensitivity to punishment could be exacerbated by the hypodopaminergic tone in ADHD.

Alterations of the reward system have been proposed as one of the core mechanisms underlying the expression of negative symptoms in schizophrenia. Specifically, deficits in specific reward components and white matter (WM) integrity of the reward system have been highlighted. The putative link between negative symptoms and the hedonic experience, or structural connectivity of the reward system has never been examined in the 22q11.2 deletion syndrome (22q11DS), a condition with increased risk for psychosis.

Anticipatory and consummatory dimensions of pleasure were assessed in participants with 22q11DS (N = 54) and healthy controls (N = 55). In patients with 22q11DS, the association between pleasure scores and positive or negative symptoms was investigated. Furthermore, WM integrity of the accumbofrontal tract was quantified using diffusion tensor imaging (DTI). Associations between DTI measures, pleasure dimensions and negative symptoms were examined.

Patients with 22q11DS showed reduced anticipatory and consummatory pleasure compared to controls. Furthermore, anticipatory pleasure scores were negatively correlated to negative and positive symptoms in 22q11DS. WM microstructural changes of the accumbofrontal tract in terms of increased fractional anisotropy and reduced radial anisotropy were also identified in patients. However, no significant correlation between the DTI measures and pleasure dimensions or psychotic symptoms was observed.

This study revealed that participants with 22q11DS differed in their experience of pleasure compared to controls. The anticipatory pleasure component appears to be related to negative and positive symptom severity in patients. Alterations of WM integrity of the accumbofrontal tract seem to be related to myelination abnormalities in 22q11DS patients.