Gene Linked to Attention Deficit.

The presence of a gene associated with Alzheimer's disease has been linked to deficits in the cognitive ability of visual attention in middle-aged individuals who don't yet display symptoms of having the disease, according to researchers at The Catholic University of America, Washington, D.C., and the National Institute of Mental Health's Geriatric Psychiatry Branch. The e4 allele of the apolipoprotein (APOE) gene, of ten present in individuals with Alzheimer's disease, has been associated with altered brain physiology in healthy adults prior to old age. Middle-aged, nondemented carriers of the gene showed deficits in two out of three tasks that measured their visual attention.

The researchers conducted three different studies to assess performance of separate aspects of visual attention: the ability to shift attention, adjust the spatial scale of attention, and to sustain attention throughout a visual task. Of the 97 individuals tested, 74 had close relatives diagnosed with Alzheimer's disease. DNA testing determined whether participants were carriers of the e2, e3, or e4 allele of the APOE gene, and they then were grouped accordingly.

In the first test, research subjects were placed at a computer and asked to identify whether a letter flashing on an empty screen was a vowel or consonant. Arrows on the screen also appeared as location cues, but were invalid part of the time...