Tag: working memory

Effects of exercise on cognitive and motor function in chronic fatigue syndrome and depression

Abstract:

OBJECTIVES: Patients with chronic fatigue syndrome complain of physical and mental fatigue that is worsened by exertion. It was predicted that the cognitive and motor responses to vigorous exercise in patients with chronic fatigue syndrome would differ from those in depressed and healthy controls.

METHODS: Ten patients with chronic fatigue syndrome, 10 with depressive illness, and 10 healthy controls completed cognitive and muscle strength testing before and after a treadmill exercise test. Measures of cardiovascular functioning and perceived effort, fatigue, and mood were taken during each stage of testing.

RESULTS: Depressed patients performed worst on cognitive tests at baseline. During the treadmill test, patients with chronic fatigue syndrome had higher ratings of perceived effort and fatigue than both control groups, whereas patients with depression reported lower mood. After exertion, patients with chronic fatigue syndrome showed a greater decrease than healthy controls on everyday tests of focused (p=0.02) and sustained (p=0.001) attention, as well as greater deterioration than depressed patients on the focused attention task (p=0.03). No between group differences were found in cardiovascular or symptom measures taken during the cognitive testing.

CONCLUSIONS: Patients with chronic fatigue syndrome show a specific sensitivity to the effects of exertion on effortful cognitive functioning. This occurs despite subjective and objective evidence of effort allocation in chronic fatigue syndrome, suggesting that patients have reduced working memory capacity, or a greater demand to monitor cognitive processes, or both. Further insight into the pathophysiology of the core complaints in chronic fatigue syndrome is likely to be realised by studying the effects of exercise on other aspects of everyday functioning.

 

Source: Blackwood SK, MacHale SM, Power MJ, Goodwin GM, Lawrie SM. Effects of exercise on cognitive and motor function in chronic fatigue syndrome and depression. J Neurol Neurosurg Psychiatry. 1998 Oct;65(4):541-6. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2170292/ (Full study)

 

Attention and verbal learning in patients with chronic fatigue syndrome

Abstract:

Former neuropsychological studies with Chronic Fatigue Syndrome (CFS) patients evaluated a broad range of cognitive functions. Several, but not all, reported subtle attentional and memory impairments suggesting possible mild cerebral involvement.

In this study, a battery of attentional tests and a verbal memory task were administered to 20 CFS patients and 22 healthy controls (HC) in order to clarify the specific nature of attention and memory impairment in these patients. The results provide evidence for attentional dysfunction in patients with CFS as compared to HC.

CFS patients performed more poorly on a span test measuring attentional capacity and working memory. Speeded attentional tasks with a more complex element of memory scanning and divided attention seem to be a sensitive measure of reduced attentional capacity in these patients.

Focused attention, defined as the ability to attend to a single stimulus while ignoring irrelevant stimuli, appears not to be impaired. CFS patients were poorer on recall of verbal information across learning trials, and poor performance on delayed recall may be due to poor initial learning and not only to a retrieval failure.

 

Source: Michiels V, Cluydts R, Fischler B. Attention and verbal learning in patients with chronic fatigue syndrome. J Int Neuropsychol Soc. 1998 Sep;4(5):456-66. http://www.ncbi.nlm.nih.gov/pubmed/9745235

 

Cognitive slowing and working memory difficulties in chronic fatigue syndrome

Abstract:

OBJECTIVE: Patients with chronic fatigue syndrome (CFS) commonly report problems with attention, memory, learning, and speed of cognitive processing. This study attempted to evaluate these complaints using objective test criteria.

METHOD: A test battery composed of six tests assessing these cognitive functions was given on two consecutive days. Twenty CFS patients were compared with 20 healthy control subjects and 14 patients with a history of major depression or dysthymia matched by age, intelligence, education level, and sex.

RESULTS: Compared with control subjects, CFS patients consistently scored lower on tests in which motor and cognitive processing speeds were a critical factor, eg, reaction-time tasks. They also had more difficulty on working-memory tests in which rapid cognitive processing speed is also an important factor. The effort made on the first day of testing did not result in a decline in cognitive function on the following day. CFS patients did not qualify as having affective disorder by several different diagnostic criteria. Nonetheless, CFS patients’ test performances did not differ from patients with a history of major depression or dysthymia.

CONCLUSIONS: It is concluded that, although CFS and major depression and dysthymia have distinct clinical features, these disorders have slowed motor and cognitive processing speed in common.

Comment in: Cognitive slowing in chronic fatigue syndrome (CFS) [Psychosom Med. 1997]

 

Source: Marshall PS, Forstot M, Callies A, Peterson PK, Schenck CH. Cognitive slowing and working memory difficulties in chronic fatigue syndrome. Psychosom Med. 1997 Jan-Feb;59(1):58-66. http://www.ncbi.nlm.nih.gov/pubmed/9021867

 

Selective impairment of auditory processing in chronic fatigue syndrome: a comparison with multiple sclerosis and healthy controls

Abstract:

The most consistent deficit observed in individuals with Chronic Fatigue Syndrome has been in efficiency of information processing. To examine the possibility of a modality-specific impairment, the present study examined subjects with Chronic Fatigue Syndrome, multiple sclerosis, and healthy controls on an auditory-versus visual-paced serial-addition test. 20 subjects with Chronic Fatigue Syndrome, 20 subjects with clinically definite Multiple Sclerosis, and 20 sedentary healthy controls were compared.

One-half of the subjects in each group were administered the Paced Auditory Serial Addition Test and the other half were administered the Paced Visual Serial Addition Test. The group with Chronic Fatigue Syndrome was differentially impaired on the auditory relative to the visual processing task. The group with Multiple Sclerosis was equally impaired on both versions of the task. The results are discussed within the framework of Baddeley’s model of working memory.

 

Source: Johnson SK, DeLuca J, Diamond BJ, Natelson BH. Selective impairment of auditory processing in chronic fatigue syndrome: a comparison with multiple sclerosis and healthy controls. Percept Mot Skills. 1996 Aug;83(1):51-62. http://www.ncbi.nlm.nih.gov/pubmed/8873173