Subtle brain abnormalities predict mental decline: study

NEW YORK (Reuters Health) - Subtle neurological abnormalities in apparently healthy older adults are independent risk factors for cognitive and functional decline and death, according to an Italian study reported in the Archives of Internal Medicine.

"This study reaffirms that subtle neurologic abnormalities are frequent and should be systematically investigated in older adults, even when they are not referred to the physician for neurological problems," lead author Dr. Marco Inzitari told Reuters Health.

To examine the association between subtle neurologic abnormalities and health outcomes, Inzitari, currently at the Aging Institute of the Autonomous University of Barcelona, and colleagues conducted neurological assessments of 506 subjects who were 65 years or older (average age 72.5 years) in 1996. The subjects had no history of stroke, dementia, cognitive impairment, or Parkinson's disease.

The evaluation included measures of muscle strength; physical sensitivity; deep tendon reflexes; plantar reflex (used to evaluate the neural pathways that control the lower limbs); plus the Purdue Pegboard Test, as a measure of executive function. Executive function refers to the ability to control thought processes and behaviors. For example, it is used to organize thoughts, plan activities and initiate goal-directed behavior.

The researchers tallied the number of subtle neurologic abnormalities (range 0-19) as a measure of neurological damage. The average number of subtle neurologic abnormalities was 1.1. Ninety-six subjects had a score of two, 38 had a score of three, and 33 had a score of four or higher.

By 2003 follow-up, 113 subjects had died and 62 had been hospitalized for a cerebrovascular event, such as a stroke. Mortality rates correlated with test scores -- as the score increased -- so did the patient mortality rate.

"Some of the specific items of our neurological exam were more prevalent than others and were more strongly associated with both poor physical and cognitive functions," including impaired reflexes and postural instability, Inzitari told Reuters Health. When the neurologic abnormalities were totaled, a score of three or more "was a very strong predictor of future health problems."

"This could mean that a given level of neurological damage, up to a critical threshold, might be required before overt consequences become apparent," he said.

The findings suggest a "possible association of these subtle neurologic abnormalities with chronic and subtle vascular brain disease," Inzitari continued. If confirmed, "the detection of multiple neurological abnormalities might prompt further cardiovascular investigation and more careful management of cardiovascular risk factors."

In an accompanying editorial, Drs. Malaz Boustani and Michael D. Justiss, at the Regenstrief Institute in Indianapolis say the research "opens the door for future research investigations using the subtle neurologic abnormalities scale as a method to identify older adults at risk for future disability and enroll them into disability prevention clinical trials."

SOURCE: Archives of Internal Medicine, June 23, 2008