SAN DIEGO – Patients recently diagnosed with Alzheimer’s disease had an increased prevalence of diagnoses for neuropsychiatric conditions that mimic symptoms of mild cognitive impairment in a large retrospective, case-control study.
The findings underscore the need for an instrument designed to help clinicians differentiate mild cognitive impairment (MCI) from other neuropsychiatric conditions, Jiao Yang, Ph.D., said in an interview at the Clinical Trials Conference on Alzheimer’s Disease.
Dr. Jiao Yang
"We need a better guidance for clinical practice," said Dr. Yang, a project statistician with Deerfield, Ill.–based Takeda Pharmaceuticals International. "We do need some type of a diagnostic test to differentiate or to detect MCI."
In an effort to characterize the 3-year period immediately preceding the first diagnosis of Alzheimer’s disease (AD) and the first 6 months after diagnosis, Dr. Yang and her associates used data from the 2010-2011 Truven Health Analytics MarketScan Commercial and Medicare Supplemental Database to identify risk and prognostic factors in 28,879 newly diagnosed AD patients with a mean age of 79 years. The researchers also randomly selected a control cohort of 28,879 patients, excluding those with dementia or taking AD medications, and matched them in a 1:1 fashion with the AD cohort on age, gender, insurance plan type, and geographic region.
The percentage of AD patients, compared with controls, who had a diagnosis of MCI at 36 months before AD diagnosis to 6 months before AD diagnosis to 6 months after AD diagnosis increased from 0.2% to 5.2% to 7.6%, compared with controls (0% at all three time points). The same significant trend occurred for diagnoses of AD-related conditions or dementias or frontotemporal dementia, dementia with Lewy bodies, and memory loss (from 1.9% to 36.2% to 48.2% for AD patients and from 0.2% to 1.1% to 1.4% for controls) and various neurologic disorders (from 5.4% to 26.4% to 31.9% for AD patients and from 1.1% to 4.2% to 4.9% for controls).
"The steeper slope of the increase in prevalence in the 6 months pre-index period seems to suggest that diagnosis of these disorders may lead a physician to test for AD, while the 6 months post-index increase could indicate higher awareness among physicians of the need to test AD patients for other similar diagnoses," Dr. Yang said.
Over time, a higher percentage of AD patients vs. controls also had anxiety disorder (from 2.4% to 6.6% to 6.5% vs. from 1.1% to 1.7% to 1.9%) and depression (from 4.6% to 11.1% to 11.6% vs. from 1.4% to 2.0% to 2.3%). The percentage of patients with cerebrovascular disease also increased with time (from 8.3% to 41.8% to 47.5% for AD patients and from 5.1% to 19.9% to 22.4% for controls), as did the percentage of patients with congestive heart failure (from 3.7% to 16.5% to 19.4% for AD patients and from 2.9% to 11.4% to 13.0% for controls).
The researchers also noted that, at each subsequent interval, a higher proportion of AD patients were using antidepressants, tranquilizers/antipsychotics, and benzodiazepines, compared with controls. In addition, 37.2% of MCI patients were primarily first diagnosed by neurologists, "possibly highlighting the difficulty of making the diagnosis," she noted in the poster presentation. "This could be due to the lack of tests or procedures to demonstrate conclusively the presence of MCI."
Takeda Pharmaceuticals International sponsored the study.