Lifestyle Affects Early Impairment?

Patients who develop dementia before age 65 years have more preventable conditions—including cognitive deficits and impaired functioning related to alcohol abuse, head trauma, and HIV—compared with patients with late-onset dementia, according to the largest series to date on early-onset dementia.

The study, presented here at the annual meeting of the American Neurological Association (ANA), showed alcohol abuse accounted for 5% of cases of early-onset dementia (dementia that strikes before age 65) versus 3% of late-onset dementia. Traumatic brain injury accounted for 24% of early-onset dementia versus 4% of late-onset dementia.

HIV accounted for 8% of early-onset dementia versus 3% of late-onset dementia. A group of rare brain disorders that affect the frontal and temporal lobes of the brain, which control speech and personality, accounted for 3% of cases of early-onset dementia versus less than 1% of late-onset dementia.

All the differences reached statistical significance, said Dr. Aaron McMurtray, a neurobehavioural fellow in the department of neurology at the University of California at Los Angeles.

Late-onset mostly due to Alzheimer's

In contrast, Alzheimer's disease accounted for 52% of cases of late-onset dementia, compared with just 17% of cases of early-onset dementia, he said.

The study, which was awarded an ANA fellowship travel award, was designed to investigate the frequency and causes of early-onset dementia versus late-onset dementia at a U.S. Veterans Affairs memory program over a four-year period, he said.

Dementia was diagnosed if patients had deficits in two or more domains of cognition sufficient to cause impairment in social or occupational functioning and representing a significant decline from a previous level of functioning.

Of the 1,683 patients who were evaluated, 948 (56.3%) met criteria for dementia. Of these, 278 (29.3%) developed dementia before age 65 years, at a mean age of 51.5 years, and 670 (70.7%) had an age of onset of 65 years or older.

Dr. Lawrence Honig (PhD), associate professor of clinical neurology in the division of dementia and aging at Columbia University in New York, said the findings confirm what is generally seen in clinical practice.

"While it is very much dependent on who refers your patient, overall we see much more Alzheimer's disease in older patients and dementia due to preventable causes such as TBI (traumatic brain injury) and alcohol abuse in younger patients," he said.

Dr. McMurtray said while the researchers were expecting Alzheimer's disease to be less prevalent in younger persons, they were surprised at their high rates of dementia due to alcohol abuse, traumatic brain injury and HIV.

The findings will be even more important as new treatments for brain injury, alcohol abuse and other causes of early-onset dementia are developed, he said.

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