Research Notes-Spring 1998
Dementia/Frailty Study Identifies Improved Assessment Techniques
by Mary Janke
In the Summer 1997 issue of Research Notes, an article on the dementia/frailty study described interim results and stated that final results "should be" available in the Fall. As often happens, this statement underestimated the time involved. But the final report is out now (it was published in December 1997) and has been sent to people and organizations on our mailing list. It is Assessing the Older Driver: Pilot Studies, by Janke and Hersch.
You may remember from the earlier article that we studied older referrals and volunteers to find non-driving "first-tier" tests that could identify those with aging-related disabilities, and non-driving "second-tier" tests that could indicate how well an identified driver would perform on a standardized road test. The second-tier tests needed to be able to predict road test errors. The road test, a modified version of DMV's Driving Performance Evaluation or DPE, was the third tier of testing in our study. (In an operational system, drivers who performed either extremely poorly or extremely well on second-tier tests might not be required to take a road test.)
In studies at the Santa Teresa field office and the Buck Center for Research in Aging (Novato), several tests showed promise. For the first tier--supposed to be made up of brief, inexpensive tests suitable for administering to applicants in the field office--we recommended structured observation of previously listed observable "problems," such as difficulty in understanding test instructions or obvious tremor, and the Pelli-Robson test of contrast sensitivity. The Pelli-Robson, sometimes called a "fog chart," presents letters that fade out gradually toward the bottom of the chart until they are essentially white on white (think of driving in extremely foggy conditions). If the contrast between letters and background is low, older people in particular have trouble making out the letters.
For the second tier (more lengthy and complex tests that ordinarily would be given only to referrals and to applicants who failed in the first tier), we recommended Auto-Trails, a PC-based test in which testees touch randomly arranged numbers in numerical order as fast as possible, and a perceptual response time test, also PC-based, which measures testees' ability to identify a silhouette flashed extremely briefly. Other tests were promising, but would probably need to be converted to PC format in order to be feasible.
The road test discriminated between referrals and volunteers, and a destination-finding task on it ("now drive back to the DMV office") discriminated between cognitively impaired referrals and referrals who were not cognitively impaired.
The report describes in detail each of the individual tests, and their performance in prediction. It also includes a chapter written by the co-author, Sandra Hersch, describing the effects, as measured by surveys, of restricting vs. revoking the licenses of older adults. Other sections describe surveys of an expert advisory panel and the American Association of Motor Vehicle Administrators. The report concludes with implications for policy and future research.
To order a copy of the report Assessing the Older Driver: Pilot Study write to DMV, Research and Development Branch at 2415 First Avenue, Mail Station F-126, Sacramento, CA 95818, Fax No. (916)657-8589, or by e-mail: dluong@dmv.ca.gov