Chest
Volume 112, Issue 6, December 1997, Pages 1506-1513
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Clinical Investigations: COPD
Verbal Memory Impairment in COPD: Its Mechanisms and Clinical Relevance

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Study objectives

Identification of mechanisms accounting for verbal memory impairment in patients with severe COPD; assessing the relationship between verbal memory and the overall cognitive performance; verifying if verbal memory impairment affects medication adherence.

Design

Case-comparison study.

Setting

Outpatient Departments of Pneumology and Neurology, Day Hospital of General Surgery.

Patients

Forty-two COPD ambulatory patients, age 70±9.7 years, with hypoxemia and hypercarbia (group A); 27 normal subjects of comparable age and educational level (group B); 31 patients with Alzheimer's disease (group C); and 26 older normal subjects (group D).

Measurements and results

The overall cognitive function and verbal memory were evaluated by the Mental Deterioration Battery and 14 indexes of verbal memory. Defective retrieval and recognition mechanisms distinguished group A from group B. According to discriminant analysis, verbal memory profile of COPD patients was group specific in 38.1% of cases and conformed to that of group B, C, and D in 19%, 16.7%, and 26.2% of cases, respectively. In COPD patients, both immediate and delayed recall, the strongest determinants of the discriminant function, were significantly correlated with the overall cognitive performance (rho=0.64, p=0.001; rho=0.61, p=0.001, respectively). Poor adherence to medication regimen was significantly associated with abnormal delayed recall score (82.3% vs 36% in subjects with normal delayed recall, p<0.008).

Conclusions

Decline of verbal memory parallels that of the overall cognitive function in COPD patients and is due to the impairment of both active recall and passive recognition of learned material. It could be an important determinant of the level of medication adherence.

Section snippets

Subjects

The verbal memory performance of patients with stabilized hypoxic and hypercapnic COPD (group A or study group) was compared with that of normal subjects of the same age (group B), Alzheimer patients (group C), and older normal subjects (group D). The previous demonstration of a peculiar verbal memory profile in the very old and of some analogies between the respective effects of aging and COPD on the cognitive functions was the rationale for including group D in the analysis.2, 4, 6

Subjects of

Results

The general characteristics of the four groups are reported in Table 2. Female subjects prevailed in groups C and D, whereas educational level and level of employment before retirement were uniform across groups, according to criteria of selection. The global cognitive performance of group A, as assessed by the MDB, was better than in Alzheimer patients, but significantly inferior to that of the remaining two groups. Table 3 reports results of verbal memory tests. The study group had

Discussion

Results from the present study disclose a great interindividual variability in verbal memory pattern of COPD patients. A group-specific verbal memory profile was found in a minority of them, while variant profiles were very common. Only a fifth of COPD patients could be considered to have normal verbal memory, that is a verbal memory pattern conforming to that of same-age normal subjects. The high proportion of COPD patients classified as belonging to the older normal group supports the

ACKNOWLEDGMENT

We wish to thank Sabina Magalini, MD, for her careful revision of this article.

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