Because there are many types of dementia, with many potential underlying causes, diagnosing it properly can be challenging. Two commonly used tests can return negative results for patients who have demonstrated abnormal cognitive test results or unexplained cognitive dysfunction.
Early detection and diagnosis of dementia is important, but for some different reasons than it is essential for other conditions. In the case of dementia, the condition may not be as treatable as conditions such as coronary artery disease, rheumatoid arthritis, or cancer. There are many different types and causes of dementia, and some respond to treatment better than others. But for dementia payments, simply understanding what is causing the problems they are experiencing and being able to find sources of support and plan for the future.
Yet, because there are many types of dementia, with many potential underlying causes, diagnosing it properly can be challenging. Two of the common tests are Mini-Mental State Examination (MMSE) and the Clock Drawing Test (CDT), but those tests can be negative for patients who have demonstrated abnormal cognitive test results or unexplained cognitive dysfunction.
A Swiss study published in BMC Geriatrics looked at the use of the Short Smell Test (SST) and the Palmo-Mental Reflex (PMR) tests—both previously used in Alzheimer’s patients but neither used previously to diagnose dementia—to see if either or both could be effective in patients who tested negative on the MMSE and the CDT but who were admitted to a Swiss Memory Clinic because of suspected dementia. The study is aimed at general practitioners but is also applicable to the practice of psychiatrists.
According to the study authors, “…we chose SST and PMR because they turn deficient early in various diffuse subcortical or cortical encephalopathies that often lead to dementia.” The study took place in one Memory Clinic that sees about 200 patients a year, of which 60% are diagnosed with dementia.
Patients were assessed in two sessions. In the first, semi-structured interviews were conducted on reason for admission, cognitive complaints, somatic problems, and behavioral and psychological symptoms of dementia (BPSD), problems in practical daily routines, somatic problems, earlier medical problems, family medical and social history. The session was followed by a clinical examination, checked for neurological abnormalities, and also included the SST and PMR. In the second session, patients were given a standardized battery of neuropsychological tests.
Simple SST was considered abnormal if patients closed their eyes and could not identify instant coffee powder in a can when it was held 5—10 cm under their nose. PMR was considered positive if brushing the thumb under the thenar (the region of the palm at the base of the thumb) elicited a unilateral chin muscle twitch.
In the study, 154 patients suspected of dementia had normal MMSE and CDT test results. Of these, 17 (11%) were demented. If SST or PMR were abnormal, sensitivity was 71% (95% CI 44—90%), and specificity 64% (95% CI 55–72%) for detecting dementia. If both tests were abnormal, sensitivity was 24% (95% CI 7–50%), but specificity increased to 93% (95% CI 88–97%). Dementia was present in over 93% of patients whose SST and PMR were both abnormal. Study limitations include small sample size and the possibility that abnormal SST can also be caused by other physiological changes in patients and normal aging.
The study authors conclude that for patients suspected of dementia but with normal MMSE and CDT results, the SST and PMR can be added diagnostic tools. “If one or both tests are normal, we do not suggest that a change in current practice is necessary: patients, caregivers and doctors should together decide the next steps to take,” the authors note. “However, abnormal results on both tests indicate that further testing is warranted.”