Postural neurocognitive and neuronal activated cerebral blood flow deficits in young chronic fatigue syndrome patients with postural tachycardia syndrome

Departments of Physiology, New York Medical College, Valhalla, New York. USA.
AJP Heart and Circulatory Physiology (Impact Factor: 3.84). 12/2011; 302(5):H1185-94. DOI: 10.1152/ajpheart.00994.2011
Source: PubMed


Neurocognition is impaired in chronic fatigue syndrome (CFS). We propose that the impairment relates to postural cerebral hemodynamics. Twenty-five CFS subjects and twenty control subjects underwent incremental upright tilt at 0, 15, 30, 45, 60, and 75° with continuous measurement of arterial blood pressure and cerebral blood flow velocity (CBFV). We used an n-back task with n ranging from 0 to 4 (increased n = increased task difficulty) to test working memory and information processing. We measured n-back outcomes by the number of correct answers and by reaction time. We measured CBFV, critical closing pressure (CCP), and CBFV altered by neuronal activity (activated CBFV) during each n value and every tilt angle using transcranial Doppler ultrasound. N-back outcome in control subjects decreased with n valve but was independent of tilt angle. N-back outcome in CFS subjects decreased with n value but deteriorated as orthostasis progressed. Absolute mean CBFV was slightly less than in control subjects in CFS subject at each angle. Activated CBFV in control subjects was independent of tilt angle and increased with n value. In contrast, activated CBFV averaged 0 in CFS subjects, decreased with angle, and was less than in control subjects. CCP was increased in CFS subjects, suggesting increased vasomotor tone and decreased metabolic control of CBFV. CCP did not change with orthostasis in CFS subjects but decreased monotonically in control subjects, consistent with vasodilation as compensation for the orthostatic reduction of cerebral perfusion pressure. Increasing orthostatic stress impairs neurocognition in CFS subjects. CBFV activation, normally tightly linked to cognitive neuronal activity, is unrelated to cognitive performance in CFS subjects; the increased CCP and vasomotor tone may indicate an uncoupling of the neurovascular unit during orthostasis.

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Available from: Julian Stewart, Feb 17, 2015
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    • "We found that patients with POTS experienced delays in attention and information processing compared with the control subjects during head up tilt. This observation is consistent with a recent report by Stewart et al. (2012) who examined cognitive performance in young chronic fatigue syndrome patients with POTS. Perhaps underpinning the acute impairment in cognitive performance, reduced cerebral blood flow and a possible uncoupling of cerebral autoregulation during head up tilt has been demonstrated in patients with POTS (Ocon et al., 2009). "
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    ABSTRACT: The Postural Orthostatic Tachycardia Syndrome (POTS) is a condition in which heart rate increases abnormally when the individual assumes an upright position. In addition to the marked tachycardia, presyncope, and syncope, patients with POTS often complain of light-headedness, fatigue, and difficulty in concentrating. The present study assessed individuals with POTS for psychiatric comorbidity, anxiety sensitivity and health related quality of life and examined general cognitive ability. Data was obtained from patients with POTS (n = 15, 12 female, aged 30 ± 3 years) and age matched healthy subjects (n = 30, 21 female, aged 32 ± 2 years). Patients with POTS commonly presented with symptoms of depression, elevated anxiety and increased anxiety sensitivity, particularly with regards to cardiac symptoms, and had a poorer health related quality of life in both the physical and mental health domains. While patients with POTS performed worse in tests of current intellectual functioning (verbal and non-verbal IQ) and in measures of focused attention (digits forward) and short term memory (digits back), test results were influenced largely by years of education and the underlying level of depression and anxiety. Acute changes in cognitive performance in response to head up tilt were evident in the POTS patients. From results obtained, it was concluded that participants with POTS have an increased prevalence of depression and higher levels of anxiety. These underlying symptoms impact on cognition in patients with POTS, particularly in the cognitive domains of attention and short-term memory. Our results indicate that psychological interventions may aid in recovery and facilitate uptake and adherence of other treatment modalities in patients with POTS.
    Frontiers in Physiology 06/2014; 5:230. DOI:10.3389/fphys.2014.00230 · 3.53 Impact Factor
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    • "Panerai and colleagues (2005) found other tests, the critical closing pressure (CCP) and resistance area product (RAP), to be better measures of cerebral blood flow responses induced by mental activation tasks rather than cerebrovascular resistance alone. Stewart et al. (2012) has found increasing orthostatic stress impairs cognitive functioning in CFS/POTS. However, these impairments are not related to cerebral blood flow using cerebrovascular resistance alone, but when CCP and RAP were used, cerebral blood flow was related to neurocognitive abilities. "
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    ABSTRACT: Chronic fatigue syndrome (CFS) is characterized by fatigue, sleep dysfunction, and cognitive deficits (Fukuda et al., 1994). Research surrounding cognitive functioning among patients with CFS has found difficulty with memory, attention, and information processing. A similar disorder, postural tachycardia syndrome (POTS), is characterized by increased heart rate, fatigue, and mental cloudiness (Raj et al., 2009). Potential implications of cognitive deficits for patients with CFS and/or POTS are discussed, including difficulties with school and/or employment. A few biological theories (i.e., kindling, impairments in the central nervous system, and difficulty with blood flow) have emerged as potential explanations for the cognitive deficits reported in both CFS and POTS Future research should continue to examine possible explanations for cognitive impairments in CFS and POTS, and ultimately use this information to try and reduce cognitive impairments for these patients.
    Frontiers in Physiology 05/2013; 4:113. DOI:10.3389/fphys.2013.00113 · 3.53 Impact Factor
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    • "To study this, work by Stewart et al. (2012) looked at how CBFv changed during increasing mental and orthostatic stress in a group of subjects with both CFS and POTS. Mental stress was induced by the n-back task, while orthostatic stress was induced with graded tilt-table testing. "
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    ABSTRACT: Chronic Fatigue Syndrome (CFS) is defined as greater than 6 months of persistent fatigue that is experienced physically and cognitively. The cognitive symptoms are generally thought to be a mild cognitive impairment, but individuals with CFS subjectively describe them as "brain fog." The impairment is not fully understood and often is described as slow thinking, difficulty focusing, confusion, lack of concentration, forgetfulness, or a haziness in thought processes. Causes of "brain fog" and mild cognitive impairment have been investigated. Possible physiological correlates may be due to the effects of chronic orthostatic intolerance (OI) in the form of the Postural Tachycardia Syndrome (POTS) and decreases in cerebral blood flow (CBF). In addition, fMRI studies suggest that individuals with CFS may require increased cortical and subcortical brain activation to complete difficult mental tasks. Furthermore, neurocognitive testing in CFS has demonstrated deficits in speed and efficiency of information processing, attention, concentration, and working memory. The cognitive impairments are then perceived as an exaggerated mental fatigue. As a whole, this is experienced by those with CFS as "brain fog" and may be viewed as the interaction of physiological, cognitive, and perceptual factors. Thus, the cognitive symptoms of CFS may be due to altered CBF activation and regulation that are exacerbated by a stressor, such as orthostasis or a difficult mental task, resulting in the decreased ability to readily process information, which is then perceived as fatiguing and experienced as "brain fog." Future research looks to further explore these interactions, how they produce cognitive impairments, and explain the perception of "brain fog" from a mechanistic standpoint.
    Frontiers in Physiology 04/2013; 4:63. DOI:10.3389/fphys.2013.00063 · 3.53 Impact Factor
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