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Neuroscience. 2015 Feb 12;286:371-82. doi: 10.1016/j.neuroscience.2014.11.052. Epub 2014 Dec 6.

Psychophysiological correlates of cognitive deficits in family caregivers of patients with Alzheimer Disease.

Author information

1
Laboratório de Biologia e Desenvolvimento do Sistema Nervoso, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga Av. 6681, Building 12D, Room 304, 90619-900 Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga Av. 6681, Building 12A, 90619-900 Porto Alegre, RS, Brazil; Instituto Nacional Ciência e Tecnologia - Medicina Translacional (INCT-TM), RS, Brazil.
2
Laboratório de Biologia e Desenvolvimento do Sistema Nervoso, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga Av. 6681, Building 12D, Room 304, 90619-900 Porto Alegre, RS, Brazil; Instituto Nacional Ciência e Tecnologia - Medicina Translacional (INCT-TM), RS, Brazil.
3
Laboratório de Psiquiatria Molecular, Hospital de Clínicas de Porto Alegre, Ramiro Barcelos St. 2.350, 90035-903 Porto Alegre, RS, Brazil; Instituto Nacional Ciência e Tecnologia - Medicina Translacional (INCT-TM), RS, Brazil.
4
Instituto de Geriatria e Gerontologia, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga Av. 6681, Room 703, 90610-000 Porto Alegre, RS, Brazil.
5
Laboratório de Psiquiatria Molecular, Hospital de Clínicas de Porto Alegre, Ramiro Barcelos St. 2.350, 90035-903 Porto Alegre, RS, Brazil; Instituto Nacional Ciência e Tecnologia - Medicina Translacional (INCT-TM), RS, Brazil; Faculdade Unilasalle, Canoas, RS, Brazil.
6
Laboratório de Biologia e Desenvolvimento do Sistema Nervoso, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga Av. 6681, Building 12D, Room 304, 90619-900 Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga Av. 6681, Building 12A, 90619-900 Porto Alegre, RS, Brazil; Instituto de Geriatria e Gerontologia, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga Av. 6681, Room 703, 90610-000 Porto Alegre, RS, Brazil; Instituto Nacional Ciência e Tecnologia - Medicina Translacional (INCT-TM), RS, Brazil. Electronic address: bromberg@pucrs.br.

Abstract

BACKGROUND:

The progressive loss of memory and autonomy of Alzheimer's Disease (AD) patients, together with their characteristic behavioral and psychological symptoms, subjects their family caregivers to chronic stress. Several studies indicate that these caregivers are predisposed to cognitive impairments, but the physiological correlates of these alterations remain to be elucidated.

OBJECTIVE:

Analyze the effects of chronic stress of family caregivers of AD patients on cognition, cortisol/DHEA ratios and BDNF levels and investigate the relation between these variables.

EXPERIMENTAL PROCEDURE:

Seventeen family caregivers (64.83 ± 3.64 years) of patients with AD and eighteen non-caregivers (58.29 ± 3.16 years) completed stress, depression and anxiety inventories. Exclusion criteria were current neurological disorders, major unstable medical illnesses, use of medications that could interfere with cognitive or HPA axis function and dementia. Attention, working memory and executive function were assessed with Digit Span and Trail Making tests, and declarative memory was analyzed with the Logical Memory test. Saliva was collected at 8 AM and 10 PM and its cortisol and DHEA levels determined by radioimmunoassay. Serum BDNF levels were measured by sandwich-ELISA. Results were analyzed with independent samples t test, covariance analysis and linear regressions. The statistical significance was set at p<0.05 and all p values were adjusted with Holm's Method.

RESULTS:

Caregivers showed more stress, depression and anxiety symptoms than non-caregivers, as well as significantly worse performances on attention, working memory and executive function tests. Caregivers also had higher cortisol/DHEA ratios and lower BDNF levels than non-caregivers. Cortisol/DHEA ratios, especially at 10 PM, were negatively related with all cognitive tasks in which caregivers showed impaired performance. On the other hand, the only cognitive task that related with the BDNF level was digit span.

CONCLUSIONS:

This study showed that caregivers' cognitive impairment is related with alterations on cortisol/DHEA ratios, and that chronic stress experienced by these subjects has the potential to alter their BDNF levels.

KEYWORDS:

BDNF; DHEA; caregivers; chronic stress; cognitive deficits; cortisol

[Indexed for MEDLINE]

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