1008 — Head Injury in Older Veterans and Risk of Dementia
Barnes DE (REAP - San Francisco), Krueger KR
(REAP - San Francisco), Byers AL
(REAP - San Francisco), Yaffe K
(REAP - San Francisco)
The relationship between head injury and risk of dementia remains controversial, with some studies suggesting an increased risk and some finding no association. The goal of our study was to describe the primary types of head injury diagnosed in older veterans and to examine their association with developing dementia over seven years.
We performed a retrospective cohort study of 281,540 U.S. veterans age > 55 years who had at least one inpatient or outpatient visit during both the baseline (1997-2000) and follow-up (2001-2007) assessment periods, and who did not have dementia prior to follow-up. Head injury and dementia diagnoses were determined using International Classification of Diseases – 9th edition (ICD-9) codes (head injury: 310.2, 800-804, 850, 854, 959.01; dementia: 290.0-209.4, 331.2, 294.8, 331.0, 331.1, 331.82). Cox proportional hazards models were used to determine whether head injury of any type was associated with greater risk of incident dementia, adjusting for demographics, medical comorbidities, and psychiatric disorders.
Veterans had a mean age of 67 +/- 8 years at baseline, and 4% were women. Approximately 2% of veterans had a head injury diagnosis during the baseline assessment period. Diagnoses included intracranial injury (40%), unspecified head injury (34%), concussion (15%), post-concussion syndrome (12%), and skull fracture (5%), with 6% having more than one diagnosis. The risk of dementia was 6.8% in those without a head injury compared to 15.3% in those with any type of head injury (intracranial injury, 15.7%; unspecified head injury, 16.0%; concussion, 11.6%; post-concussion syndrome, 15.6%; skull fracture, 14.9%; all p < 0.001). The adjusted hazard ratio (95% confidence interval) for incident dementia in those with any head injury was 2.6 (2.4-2.8) and was significant for all head injury types.
Head injury in older veterans is associated with more than a two-fold increase in risk of developing dementia over seven years. This association is present regardless of the type of head injury and is independent of comorbid and psychiatric conditions.
Our findings suggest that head injury in older veterans may predispose toward development of symptomatic dementia, and that clinicians should monitor these veterans closely for development of new symptoms.