Despite the widespread prevalence of generalized anxiety disorder (GAD) in later life, almost nothing is known about the neural aspects of worry in adults over the age of 60. Given the ongoing rapid increase in the older adult population, the relatively poor response rates to current interventions for late life GAD, and the effects of age-related changes to the brain, additional research on worry neurobiology is needed. The study group comprised 15 older GAD patients and 15 matched controls who were compared on clinical measures and brain volumes. It was expected that prefrontal cortex (PFC) volumes [medial orbital cortex (mOFC), dorsolateral cortex (DLPFC)] would show positive relations to worry scores, and weaker relations to more general measures of anxiety and depression. Negative relations were expected between amygdala volumes and worry scores. As expected, mOFC volumes were positively related to worry scores; however, DLPFC and amygdala volumes were not. The mOFC is involved in emotional decision-making under uncertain conditions and has the ability to suppress the amygdala, both of which are hypothesized functions of worry. Results are partly consistent with GAD theory and suggest that worry may involve neural areas that are also involved in the successful control of anxiety.
The world's older adult population is increasing at an estimated rate of 800,000 people per month (Kinsella and Velkoff, 2001), which will have a dramatic impact on global health issues. For instance, along with the growing older adult population comes a corresponding expectation of increased rates of psychiatric conditions such as anxiety and depression (Jeste et al., 1999 and Blazer, 2003). However, research in anxiety disorders has not kept pace with the aging trend. Mental health specialists now face a burgeoning public health problem, given the relative lack of empirical knowledge to inform the conceptualization and treatment of late life anxiety.
Generalized anxiety disorder (GAD), a condition characterized by excessive, uncontrollable worry, is the most common anxiety disorder among adults over the age of 60, with estimated prevalence rates ranging widely from 0.71 to 7.3% (Flint, 1994, Beekman et al., 1998 and Flint, 1999). Current diagnostic criteria according to the Diagnostic and Statistical Manual IV-TR (DSM-IV-TR; American Psychiatric Association, 2000) require at least 6 months of frequent worry about several real-life problems, occurring more days than not, accompanied by at least three associated symptoms such as tension, fatigue, irritability, trouble concentrating, or insomnia. GAD is a prevalent but underrecognized public health problem, associated with significant functional impairment ( Mogotsi et al., 2000), serious disability ( Kessler et al., 1999), and increased risk for acquisition of additional psychiatric disorders and medical conditions ( Brown et al., 1994, Kennedy and Schwab, 1997, Noyes, 2001 and Barger and Sydeman, 2005). Response rates in most studies of late life GAD pharmacological and psychosocial treatment are surprisingly low ( Mohlman, 2004 and Mitte, 2005), highlighting the need for additional data on the causal and maintenance factors of the disorder.
