Increased nonlinearity end decreased chaoticity of heart rate time series in patients with panic disorder

Rao, Radha Krishna KA and Yeragani, VK Yeragani (2000) Increased nonlinearity end decreased chaoticity of heart rate time series in patients with panic disorder. In: Biological Psychiatry, 47 (08). p. 237.

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Abstract

This study investigated measures of nonlinearity (NL) and a measure of predictability and chaoticity of heart rate time series by quantifying the Largest Lyapunov Exponent (LLE) in 23 normal control subjects (31.3 6 7.6 years) and 32 patients with a diagnosis of panic disorder (31.6 6 5.1 years). The mean supine and standing heart rates were significantly higher in patients with panic disorder (Controls: 61.7 6 8.2 and 71.3 6 8.7; Patients: 71.3 6 8.7 and 85.9 6 10.0 beats per minute; p , 0.05). NL score was significantly higher in patients with panic disorder, especially in supine posture (6.1 6 2.9 vs 10.6 6 2.7; t 5 5.94; p 5 0.00001), possibly due to an increased sympathetic activity. Embedding dimension was significantly higher in patients in supine posture compared to controls (12.1 6 1.8 vs 14.2 6 1.8; t 5 4.4; p 5 0.0001) possibly due to an increase in the number of parameters that were affecting the system. LLE was significantly lower in patients in supine (0.138 6 0.024 vs 0.110 6 0.017; t 5 5.13; p 5 0.00001) as well as in standing (0.183 6 0.036 vs 0.153 6 0.014; t 5 4.13; p 5 0.0001) postures. Decreased LLE signifies increased predictability and decreased chaoticity in patients, which may be due to a decrease in some aspects of cardiac vagal function. Sex did not have any effect on these measures. Analysis of covariance using heart rate as a covariate did not change the significance of the results.

Item Type:	Journal Article
Publication:	Biological Psychiatry
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Biological Sciences
Date Deposited:	21 Aug 2009 06:12
Last Modified:	19 Sep 2010 04:59
URI:	http://eprints.iisc.ac.in/id/eprint/17931

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