Have been reported with PD pathophysiology

The thalamus and amygdala are important in the generation of a normal fear response and play a central role in most anxiety disorders. The thalamus provides the first real processing region to organize sensory data obtained from the environment. It passes information to higher cortical centers for finer processing and to the amygdala for rapid assessment of highly charged emotional information. The amygdala provides the emotional importance of the information. This helps the organism to act quickly on ambiguous but vital events. The cortex then performs a more detailed analysis, and sends updates to the amygdala for comparison and any needed course corrections, thus enabling a decision on a course of action.

Anxiety can become independent of stimuli as in PD, be associated with benign stimuli as in phobias, or continue beyond the stimulus duration as in GAD. The precise mechanism by which these changes occur is unknown, but much has been discovered regarding how this may be regulated by treatment (Fig. 40-1).

Direct and indirect connections to the reticular activating system (RAS), a region spanning the medulla, pons, and midbrain, help to regulate arousal, vigilance, and fear. These connections are modulated by serotonin and norepinephrine, which have their primary origins in the RAS.14 The amygdala sends projections to the hypothalamus, thus influencing the autonomic nervous system to affect heart rate, blood pressure, and stress-associated changes. It also influences the hypothalam-ic-pituitary-adrenal (HPA) axis, leading to a cascade of stress hormones.15 One such hormone is cortisol, which, if elevated for prolonged periods, can damage the brain and other organs. These are important targets in our understanding of how the amygdala regulates the fear response.

Amygdala Pathophysiology

FIGURE 40-1. Neurocircuitry and key neurotransmitters involved in mediating anxiety disorders. Noradrenergic System

Norepinephrine (NE)-producing cells reside primarily in a region of the brain called the locus ceruleus (LC). Increased activity in this region is associated with an increase in arousal, anxiety, and panic. Drugs such as yohimbine that increase activity in the LC can be anxiogenic, whereas drugs that decrease activity in the LC appear to improve anxiety symptoms. Furthermore, dysregulation of this region is implicated by elevated levels of NE or its metabolites in subjects with GAD, PD, and specific phobias.15

FIGURE 40-1. Neurocircuitry and key neurotransmitters involved in mediating anxiety disorders. Noradrenergic System

Norepinephrine (NE)-producing cells reside primarily in a region of the brain called the locus ceruleus (LC). Increased activity in this region is associated with an increase in arousal, anxiety, and panic. Drugs such as yohimbine that increase activity in the LC can be anxiogenic, whereas drugs that decrease activity in the LC appear to improve anxiety symptoms. Furthermore, dysregulation of this region is implicated by elevated levels of NE or its metabolites in subjects with GAD, PD, and specific phobias.15

Anxiety and Depression 101

Anxiety and Depression 101

Everything you ever wanted to know about. We have been discussing depression and anxiety and how different information that is out on the market only seems to target one particular cure for these two common conditions that seem to walk hand in hand.

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