Modulação autonômica do coração avaliada pela variabilidade da freqüência cardíaca, e sua correlação com a função cognitiva na Doença de Alzheimer

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Alzheimers disease (AD) is the most common cause of neurodegenerative dementia among elderly people. Along the years, studies searching for the neurological basis for the Alzheimers disease were particularly aimed at the central neurotransmission, especially in relation to the cholinergic system. The clinical manifestations of cognitive and functional activities decline and behavior disorders are associated with the compromising of the cholinergic system since the earliest stages of the disease. Since acetylcholine is the main neurotransmitter in the parasympathetic branch of the autonomic nervous system (ANS) and in the preganglionar sympathetic neurotransmission, it is possible that the autonomic nervous system is altered in the AD. The objective of the present study is to evaluate and compare the heart autonomic function using the heart rate variability in the time and frequency domains in short-term records (5 minutes) in two functional positions (supine and orthostatic) in 22 patients with AD, who fulfilled the diagnostic criteria for the Alzheimers disease by the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) and probable AD by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimers Disease and Related Disorders Association (NINCDS/ADRDA) and were led to the geriatrics service of the Brasilia University Hospital, and 24 healthy old-aged fellows from the community, all with 4-years minimum educational level. The correlation between autonomic cardiac function and mental status was also performed by means of three cognitive evaluation tests (CAMCOG, CDR and Mini Mental Status Exam) in patients with AD. The 24 healthy volunteers did not present cognitive alterations in the tests performed (CAMCOG; Stroop Test; Digit Span; Digit Symbol ; Mental control test; Trail Making part A and B and Auditory Verbal Learning Test ) or clinical or electrocardiographic evidence of any disease, and were making use of no medication at all. AD patients presenting score above 4 in the Hachinski scale; alterations in the image exam (computed tomography or magnetic ressonance) or those making use of any medication, as well as those presenting any clinical evidence of other disease else than AD were excluded from the study. Their ages ranged from 60 to 89 years (mean 79.6 1.4) in the group with AD and from 60 to 91 years (mean 68.6 1.6) in the group of healthy volunteers. The dementia evolution time ranged from 2-15 years, and six patients presented light dementia (CDR = 1), five presented moderate dementia (CDR = 2) and eleven presented severe dementia (CDR = 3). The CAMCOG score ranged from 0 to 74 (mean 24.14 25.99) and the MEEM from 5 to 18 (mean 6,77 6,86). All patients were able to walk without any help or with minimum help. The temporal and spectral analysis of the heart variability evidenced absolute and relative depression of the parasympathetic activity as well as an increase on the absolute and relative sympathetic activity, regardless the age differences among the groups. Significant and positive correlation between temporal and spectral indexes that express parasympathetic activity and cognitive function was also observed in the AD group in the three cognitive evaluation tests employed. These data suggest an autonomic dysfunction in patients with Alzheimers disease, characterized by mild to moderate absolute and relative parasympathetic depression and relative sympathetic exacerbation, with sympathovagal imbalance towards the sympathetic dominance, which was correlated with the cognitive function.

ASSUNTO(S)

ciencias da saude cognitive impairment alzheimer s disease alteração cognitiva variabilidade da freqüência cardíaca doença de alzheimer função autonômica cardíaca cardiac autonomic function. heart rate variability

ACESSO AO ARTIGO

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