Patients with chronic insomnia have selective impairments in memory that are modulated by cortisol

Abstract

Memory impairment is a frequent complaint in insomniacs; however, it is not consistently demonstrated. It is unknown whether memory impairment in insomniacs involves neuroendocrine dysfunction. The participants in this study were selected from the clinical setting and included 21 patients with chronic insomnia disorder (CID), 25 patients with insomnia and comorbid depressive disorder (CDD), and 20 control participants without insomnia. We evaluated spatial working and reference memory, object working and reference memory, and object recognition memory using the Nine Box Maze Test. We also evaluated serum neuroendocrine hormone levels. Compared to the controls, the CID patients made significantly more errors in spatial working and object recognition memory (p < .05), whereas the CDD patients performed poorly in all the assessed memory types (p < .05). In addition, the CID patients had higher levels (mean difference [95% CI]) of corticotrophin-releasing hormone, cortisol (31.98 [23.97, 39.98] μg/l), total triiodothyronine (667.58 [505.71, 829.45] μg/l), and total thyroxine (41.49 [33.23, 49.74] μg/l) (p < .05), and lower levels of thyrotropin-releasing hormone (-35.93 [-38.83, -33.02] ng/l), gonadotropin-releasing hormone (-4.50 [-5.02, -3.98] ng/l) (p < .05), and adrenocorticotropic hormone compared to the CDD patients. After controlling for confounding variables, the partial correlation analysis revealed that the levels of cortisol positively correlated with the errors in object working memory (r = .534, p = .033) and negatively correlated with the errors in object recognition memory (r = -.659, p = .006) in the CID patients. The results suggest that the CID patients had selective memory impairment, which may be mediated by increased cortisol levels.

The Correlations Between TNF System and Memories in Chronic Insomnia Disorder

“…Increasing findings have shown that CID patients possess significantly objective memory impairment [3-5, 23, 24]. Our current study once again demonstrated that CID patients had SWM and ORcM impairments (see Table 2), consistent with our previous findings [5,12]. Nevertheless, little is known about the mechanism of memory impairment in the CID patients.…”

“…It is sensitive to the deficits of visuo-spatial memory [9]. Consistently, our previous studies showed that the modified Nine Box Maze Test can detect mild-damaged spatail working memory (SWM) and object recognition memory (ORcM) [5,12] or and object working memory (OWM) [12] in the CID patients or SWM, OWM and spatial reference memory (SRM) in the chronic tensiontype headache patients [13]. However, the mechanisms of objectively special-impairment memories in the CID patients have not been known well.…”

“…Nine Box Maze Test [9] was mildly modified to evaluate multiple aspects of memory [5,12,13], i.e., SWM, OWM, SRM, object reference memory (ORM), and ORcM. In brief, the protocol could be described as follow.…”

“…Chronic insomnia disorder (CID) is a subjective experience of persistent sleep initiation, maintenance difficulties and/or early awakening, which can lead to some kinds of daytime functional impairments [1]. The current evidence suggests that patients with CID have not only dysfunctions of subjective learning and memory [2] but also selective impairments of objective memories [3][4][5]. Spatial memory is responsible for identifying, coding, storage and retrieval of spatial information about the arrangement of objects or specific routes [6,7].…”

Alternative Strategies for Managing Insomnia: The Case of Physical Exercise and Transcranial Direct Current Stimulation. A Narrative Review

“…It has been demonstrate that acute physical exercise is linked with insomnia symptoms via cortisol levels since the contents of this hormone have been found increased after acute high-intensity training [26,27]. An elevated cortisol levels in the evening correlate with the number of bouts of nocturnal awakenings in insomnia patients [28]. However, chronic moderate aerobic exercise using treadmill with an initial velocity of 4 km/h, increasing speed by 0.5 km/h each minute until voluntary exhaustion (3 times/week/4 months) decreased the cortisol levels, reduced sleep onset latency, and significantly increased total sleep time [29].…”