Odor Identification May Be Able to Detect Risk for Cognitive Decline, Study Finds

Olfactory senses may be used for more than determining pleasant or undesirable aromas, that may someday be a tool to assist in predicting risk for memory loss in late life.
From 2004 to 2010, Davangere Devanand, M.B.B.S., M.D., director of geriatric psychiatry at the New York State Psychiatric Institute and a professor of psychiatry at Columbia University, led a series of tests in a multiethnic population of 1,037 senior citizens without a diagnosis of cognitive dysfunction to determine whether a relationship exists between the inability to identify smells and a diagnosis of mild cognitive decline. Odor identification was measured by the University of Pennsylvania Smell Identification Test (UPSIT). 

The results, presented recently at the 2014 Alzheimer’s Association International Conference in Copenhagen, showed that 210 participants transitioned to either dementia or Alzheimer’s disease (AD) during follow-up two to four years after initial UPSIT was administered. Transition to dementia and AD was correlated with lower odor-identification scores on the UPSIT, even after adjusting for demographics, cognitive and functional measures, and apolipoprotein E genotype. Each one-point deduction on the UPSIT was associated with an approximately 10 percent increase in AD risk. 

Dolores Malaspina, M.D., a professor of psychiatry at New York University who has studied the link between olfactory senses and psychiatric illness, told Psychiatric News that, "while sensory and other processes can decline with aging, even in persons without dementia, olfactory process entails important connections in the areas that are most sensitive to the [amyloid-beta] accumulation that is associated with Alzheimer’s pathology. These results show that there may be a great potential in using olfactory-processing tests, along with other measures, to provide an early identification of those at risk for Alzheimer's disease."

To watch Davanand give an overview of the study, "Olfactory Identification Deficits Predict the Transition From MCI to AD in a Multiethnic Community Sample," click here. To read about research on how physiological factors might be used to predict risks of neurocognitive decline, see the Psychiatric News articles, "Plasma APOE Levels Linked to Dementia Risk," and "Hearing Loss in Seniors Linked to Cognitive Decline." 

(Image: Courtesy of the Alzheimer's Association)

Children With ADHD Show Olfactory Deficits

Children with attention-deficit/hyperactivity disorder (ADHD) may not be able to smell as well as their peers, and researchers say that olfactory function might be a useful biological marker for early diagnosis, treatment, and prognosis of ADHD. Researchers at the Research Center for Psychiatry and Behavioral Sciences at the Shiraz University of Medical Sciences in Iran published in the June Psychiatry Investigation the results of their study of 50 participants aged 8 to 15 with ADHD who were compared with 50 controls. The two groups were matched for age, gender, and Mean School Scores (MSS). They assessed odor identification and threshold through a smell test composed of two tests of identification and detection threshold. Odor identification was assessed using chemical essences of five common odorants.

The mean Sensory Identification Score for children with ADHD and for the control group was 3.76 and 4.46, respectively. The mean for Sensory Threshold Score for the ADHD subjects and for the control group was 6.4 and 9.75, respectively. The researchers said their results do not seem to be a result of olfactory task difficulty and were not influenced by age, gender, or MSS.

Recent research has also identified rare genetic variations in children with ADHD that may help identify children at risk for developing the disorder. Read more about those findings in Psychiatric News, here. 

(image: n Goldswain/Shutterstock.com)