The cortisol awakening response predicts response inhibition in the afternoon of the same day

The cortisol awakening response (CAR) is the rapid increase of cortisol levels 30–45 minutes after awakening in the morning. Numerous studies have indicated the relationship between the CAR and cognition. However, little is known about daily variation in the CAR and cognitive function in healthy adults. The aim of the present study was to investigate whether the CAR predicted the response inhibition function on the same day in both behaviour and the dynamic time course of brain processing. The saliva samples of 47 healthy men were collected at three time points: immediately on awakening, 30 minutes and 45 minutes post-awakening in the morning. Participants performed a Go/NoGo task while electroencephalograms (EEG) were recorded in the afternoon of the same day. The results showed that a greater CAR was associated with a stronger N2. In the sub-group of CAR responders (n = 33) the CAR was negatively related to the false alarm rate of NoGo-trials. Our findings suggested that the CAR was predictive of the function of response inhibition in both the earlier cognitive step (i.e., conflict monitoring) and the behavioural performance of response inhibition on the same day in healthy men

Cortisol awakening response predicts intrinsic functional connectivity of the medial prefrontal cortex in the afternoon of the same day

Cortisol awakening response (CAR) is the cortisol secretory activity in the first 30-60 min immediately after awakening in the morning. Alterations in CAR as a trait have been associated with changes in the brain structure and function. CAR also fluctuates over days. Little, however, is known about the relationship between CAR as a state and brain activity. Using resting-state functional magnetic resonance imaging (fMRI), we investigated whether the CAR predicts intrinsic functional connectivity (FC) of the brain in the afternoon of the same day. Data from forty-nine healthy participants were analyzed. Salivary cortisol levels were assessed immediately after awakening and 15, 30 and 60min after awakening, and resting-state fMRI data were obtained in the afternoon. Global FC strength (FCS) of each voxel was computed to provide a whole-brain characterization of intrinsic functional architecture. Correlation analysis was used to examine whether CAR predicts the intrinsic FC of core brain networks. We observed that the CAR was positively correlated with the FCS of the medial prefrontal cortex (mPFC). Further analysis revealed that higher CAR predicted stronger positive mPFC connectivity with regions in the default mode network. Our findings suggest that the HPA activity after awakening in the early morning may predict intrinsic functional connectivity of mPFC at rest in the afternoon of the same day. (C) 2015 Elsevier Inc. All rights reserved

Brain structure and function in primary adrenal insufficiency

Individuals with primary adrenal insufficiency (PAI), i.e., congenital adrenal hyperplasia (CAH) and autoimmune Addison’s disease (AAD), suffer from impaired production of the adrenal gland hormones cortisol and aldosterone, and in the case of AAD, also androgens. Replacement medication for these hormones is sub-optimal due to the difficulties in replicating the natural rhythms of cortisol secretion. The hormones are known to affect brain function via many mechanisms, and both pre- and postnatal hormone dysregulation may affect cognitive functioning, brain structure and brain function. Therefore, studying brain health in PAI is of interest and is needed to optimise treatment and patient wellbeing. The present thesis investigated brain structure related to cognitive functioning in individuals with CAH, and cognitive functioning, brain structure and resting-state functional connectivity in individuals with AAD. We found that individuals with CAH have impairments in white matter microstructure, as well as cortical thinning of the frontoparietal network that was related to weaker performance on a visuospatial working memory task. On the other hand, individuals with AAD performed equally to control subjects on most measures of cognitive functions assessed with standardized tests during the lab-visit, but they self-reported executive function problems in daily life, which were related to experienced mental fatigue. As opposed to individuals with CAH, those with AAD did not have profound differences in the structure of the brain, apart from smaller total brain volumes. However, they displayed increased resting-state functional connectivity, particularly in primary visual regions and the orbitofrontal cortex. Our results suggest that the effects of adrenal hormone insufficiency affect individuals with CAH and AAD differently. This difference may be related to the onset of the disease, which is from conception for those with CAH and in adolescence or adulthood for those with AAD. Long-term follow-up studies are needed to assess whether the observed differences contribute to increased cognitive decline later in life and how to optimise replacement medication to sustain brain health