Tag: neurocognitive functioning

Increasing orthostatic stress impairs neurocognitive functioning in chronic fatigue syndrome with postural tachycardia syndrome

Abstract:

CFS (chronic fatigue syndrome) is commonly co-morbid with POTS (postural tachycardia syndrome). Individuals with CFS/POTS experience unrelenting fatigue, tachycardia during orthostatic stress and ill-defined neurocognitive impairment, often described as ‘mental fog’. We hypothesized that orthostatic stress causes neurocognitive impairment in CFS/POTS related to decreased CBFV (cerebral blood flow velocity).

A total of 16 CFS/POTS and 20 control subjects underwent graded tilt table testing (at 0, 15, 30, 45, 60 and 75°) with continuous cardiovascular, cerebrovascular, and respiratory monitoring and neurocognitive testing using an n-back task at each angle. The n-back task tests working memory, concentration, attention and information processing. The n-back task imposes increasing cognitive challenge with escalating (0-, 1-, 2-, 3- and 4-back) difficulty levels. Subject dropout due to orthostatic presyncope at each angle was similar between groups.

There were no n-back accuracy or RT (reaction time) differences between groups while supine. CFS/POTS subjects responded less correctly during the n-back task test and had greater nRT (normalized RT) at 45, 60 and 75°. Furthermore, at 75° CFS/POTS subjects responded less correctly and had greater nRT than controls during the 2-, 3- and 4-back tests. Changes in CBFV were not different between the groups and were not associated with n-back task test scores.

Thus we conclude that increasing orthostatic stress combined with a cognitive challenge impairs the neurocognitive abilities of working memory, accuracy and information processing in CFS/POTS, but that this is not related to changes in CBFV. Individuals with CFS/POTS should be aware that orthostatic stress may impair their neurocognitive abilities.

 

Source: Ocon AJ, Messer ZR, Medow MS, Stewart JM. Increasing orthostatic stress impairs neurocognitive functioning in chronic fatigue syndrome with postural tachycardia syndrome. Clin Sci (Lond). 2012 Mar;122(5):227-38. doi: 10.1042/CS20110241. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368269/ (Full article)

 

Single-photon emission computerized tomography and neurocognitive function in patients with chronic fatigue syndrome

Erratum in: Psychosom Med. 2003 Mar-Apr;65(2):210.

 

Abstract:

OBJECTIVE: The purposes of this study were to compare functional imaging under control and experimental conditions among patients with chronic fatigue syndrome (CFS) and healthy persons and to examine perceived and objective performance on a test of attention and working memory previously found to be difficult for persons with CFS.

METHODS: Single-photon emission computerized tomography scans were completed on 15 subjects with CFS and 15 healthy persons twice: at rest and when performing the Paced Auditory Serial Addition Test (PASAT).

RESULTS: No group differences were found for performance on the PASAT despite CFS subjects’ perceptions of exerting more mental effort to perform the task than healthy subjects. Inspection of the aggregate scans by group and task suggested a pattern of diffuse regional cerebral blood flow among subjects with CFS in comparison with the more focal pattern of regional cerebral blood flow seen among healthy subjects. Between-group region-of-interest analysis revealed that although CFS subjects showed less perfusion in the anterior cingulate region, the change in CFS subjects’ activation of the left anterior cingulate region during the PASAT was greater than that observed for healthy subjects. The differences were not attributable to lesser effort by the subjects with CFS, confounding effects of mood perturbation, or to poorer performance on the experimental task.

CONCLUSIONS: Further research regarding CFS subjects’ diffuse cerebral perfusion and its relationship to inefficient neuropsychological performance is warranted.

 

Source: Schmaling KB, Lewis DH, Fiedelak JI, Mahurin R, Buchwald DS. Single-photon emission computerized tomography and neurocognitive function in patients with chronic fatigue syndrome. Psychosom Med. 2003 Jan-Feb;65(1):129-36. http://www.ncbi.nlm.nih.gov/pubmed/12554824

 

Cognitive compromise following exercise in monozygotic twins discordant for chronic fatigue syndrome: fact or artifact?

Abstract:

This study examined the effects of exhaustive exercise on cognitive functioning among 21 monozygotic twin pairs discordant for chronic fatigue syndrome (CFS). The co-twin control design adjusts for genetic and family environmental factors not generally accounted for in more traditional research designs of neuropsychological function.

Participants pedaled a cycle ergometer to exhaustion; maximum oxygen output capacity (VO2max) as well as perceived exertion were recorded. Neuropsychological tests of brief attention and concentration, speed of visual motor information processing, verbal learning and recognition memory, and word and category fluency were administered with alternate forms to participants pre- and postexercise.

The preexercise neuropsychological test performance of CFS twins tended to be slightly below that of the healthy twin controls on all measures. However, twins with CFS did not demonstrate differential decrements in neuropsychological functioning after exercise relative to their healthy co-twins. Because exercise does not appear to diminish cognitive function, rehabilitative treatment approaches incorporating exercise are not contraindicated in CFS.

 

Source: Claypoole K, Mahurin R, Fischer ME, Goldberg J, Schmaling KB, Schoene RB, Ashton S, Buchwald D. Cognitive compromise following exercise in monozygotic twins discordant for chronic fatigue syndrome: fact or artifact? Appl Neuropsychol. 2001;8(1):31-40. http://www.ncbi.nlm.nih.gov/pubmed/11388121

 

Abnormal neuropsychological findings are not necessarily a sign of cerebral impairment: a matched comparison between chronic fatigue syndrome and multiple sclerosis

Abstract:

OBJECTIVE: The aim of this study was to assess the potential impact of effort in comparative studies assessing neurocognitive dysfunction in patients with and without a neurologic diagnosis.

BACKGROUND: It was hypothesized that a subgroup within a group of patients with prominent neurocognitive complaints but without a neurologic diagnosis would have impaired performance on a task originally designed to detect malingering.

METHOD: We compared the neuropsychological performance of a group of 40 patients with a definite diagnosis of multiple sclerosis (MS) with that of 67 patients with chronic fatigue syndrome (CFS). The Amsterdam Short-Term Memory Test, a forced-choice memory task, served as measure to detect submaximal effort. In addition, we administered a regular neuropsychological task generally considered to be sensitive for cognitive deterioration.

RESULTS: Compared with the MS group (13%), a larger proportion of the matched CFS group (30%) obtained scores indicative of reduced effort. In contrast, the proportions of patients scoring below the cutoff value on a conventional neuropsychological test did not differ significantly (17% of MS patients and 16% of CFS patients).

CONCLUSIONS: The results obtained raise the question of to what extent abnormal test findings in the absence of documented neurologic impairment should be interpreted as a sign of cerebral impairment. The suggestion has been made to screen more often for biased results in comparative research studies so as to enhance valid interpretation of neuropsychological findings.

 

Source: van der Werf SP, Prins JB, Jongen PJ, van der Meer JW, Bleijenberg G. Abnormal neuropsychological findings are not necessarily a sign of cerebral impairment: a matched comparison between chronic fatigue syndrome and multiple sclerosis. Neuropsychiatry Neuropsychol Behav Neurol. 2000 Jul;13(3):199-203. http://www.ncbi.nlm.nih.gov/pubmed/10910092

 

Neurocognitive functioning in chronic fatigue syndrome

Abstract:

Although substantial research has been conducted on chronic fatigue syndrome (CFS) over the past decade, the syndrome remains poorly understood. The most recent case definition describes CFS as being characterized both by disabling fatigue and by subjective reports of difficulty with concentration and “short-term” memory. However, research into the neurocognitive and psychological functioning of individuals with CFS has provided mixed objective results. The current paper reviews studies that have examined the neurocognitive and/or psychological functioning of individuals with CFS. Changes in research design and instruments employed to study individuals with CFS are suggested.

 

Source: DiPino RK, Kane RL. Neurocognitive functioning in chronic fatigue syndrome. Neuropsychol Rev. 1996 Mar;6(1):47-60. http://www.ncbi.nlm.nih.gov/pubmed/9144668