Head injuries and cognitive decline among older adults: a population-based study.

Abstract

To examine the relationship between minor and major head injuries caused by fall accidents and cognitive decline among a cohort of adults age 70 years or older (n = 588). Even a mild brain injury may affect cognitive functions. Among older adults, results from case-control studies suggest that the occurrence of head injury is positively associated with the onset of AD. The shortened version of the Mini-Mental State Examination (sMMSE) was performed and a set of demographic and clinical variables were collected at the beginning of the study. All falls were recorded during a period of 2.5 years, after which the sMMSE tests were repeated. The risk of falls causing head injury in terms of a defined cognitive decline was examined during another follow-up period of approximately 2.5 years. There was no association between the occurrence of minor head injuries and decline in sMMSE scores. A positive relationship existed between the occurrence of major head injuries and a decline in sMMSE scores. The risk of cognitive decline increased linearly as higher cut-off points were used to define the decline in sMMSE scores-with relative risks (95% CI) of 0.94 (0.47 to 1.90), 1.35 (0.64 to 2.85), 1.75 (0.78 to 3.91), 2.38 (1.02 to 5.52), and 3.72 (1.64 to 8.44)-for a decline of > or =1, > or =2, > or =3, > or =4, and > or =5 points in the sMMSE score. The high risk remained unchanged after adjustment for other potential factors contributing to cognitive decline or dementia. The risk factors associated with falls causing major head injury during the second follow-up period were high age, OR (95% CI) 3.58 (1.87 to 6.85); use of psychotropic medication, 2.04 (1.09 to 3.83); diagnosis of hypertension, 1.80 (0.96 to 3.37); and decline in sMMSE score of >5 points, 2.41 (0.86 to 6.76). Our results suggest that the occurrence of major head injury increases the risk of cognitive decline. The cause of cognitive decline may be dementia, but this assumption remains to be elucidated in future studies.