Postural hypotension and EEG variables predict cognitive decline: results from a 5-year follow-up of healthy elderly women.

Abstract

Quantified electroencephalographic activity (EEG) has been used to study normal ageing and dementia. Few studies have described longitudinal changes in the very old. A cognitive decline has been described in subjects with white-matter lesions and hypertension but the association with hypotension is unclear. Our aim was to study the predictive value of quantified EEG for the development of cognitive decline and associations with postural hypotension. Participants. Thirty-three healthy women aged 75-95 years, with no signs of cerebrovascular disease, dementia or acute illness at baseline examination took part in a longitudinal 5-year follow-up study. The women were recruited from a random selection using the Municipal Registry. Quantified EEG was assessed twice and recorded on a Siemens-Elema connected to a Biological Banker. The medical and neuropsychological examination was conducted twice. Dementia was classified according to DSM criteria. The assessment included Mini-Mental Scale Examination (MMSE), spatial and vocabulary tests. Blood pressure was measured in supine position and an orthostatic test was performed with continuous ECG recording. Seven women (cases) developed cognitive decline at the 5-year follow-up, defined as newly developed MMSE < 27 and dementia symptoms. Low beta activity at baseline predicted development of cognitive decline. The women who remained healthy at follow-up showed an increase of alpha and theta activity. The cases had a higher orthostatic blood pressure fall during tilting at baseline (16 mm Hg) than the controls (1 mm Hg, p < 0.01). The orthostatic reaction was correlated with increased levels of theta and alpha activity at follow-up (r = -0.47 to -0.52; p < 0.01). Low beta activity predicts for cognitive decline in the elderly and an orthostatic blood pressure reaction is a risk factor for cognitive decline.