Neuropsychology and Early Diagnosis of Alzheimer’s Disease and other Neurodegenerative Disorders

Friday, August 15, 2014 @ 07:08 AM  posted by Dr. Siders

New diagnostic techniques have revealed pathological changes in the brain that occur early in the process of Alzheimer’s disease and other neurodegenerative disorders.  Researchers suggest that these pathological changes can precede noticeable clinical symptoms (memory loss, personality changes) by as many as ten years (Sperling et al., 2011). Thus, by the time even subtle symptoms are present, these processes may have been taking place for years, so early diagnosis is crucial.

Unfortunately, many who suffer from Alzheimer’s disease are not diagnosed until they have experienced significant decline in cognitive ability and loss of daily functioning. 

This may occur because Alzheimer’s disease can make someone unaware of their own cognitive deficits. Often, someone suffering from Alzheimer’s disease will not report difficulties with memory and other symptoms.  Even when symptoms are known, many people will hide their difficulties from family members or clinicians out of fear that they will lose their independence.  It is important to note that early treatment is generally the most effective way to prolong a patient’s independence, so early diagnosis, as frightening as it may seem, is a patient’s best chance for leading as full a life as possible.

Even when symptoms are reported to a clinician, many clinicians will base their diagnostic decisions on screening tests that are not sensitive to subtle cognitive declines indicative of a neurodegenerative disorder in the early stages.  For example, the Mini Mental Status Exam (MMSE) still remains the most commonly used test to screen for cognitive deficits. However, in several studies involving participants with mild cognitive impairment (MCI, a term describing less intense level of cognitive impairment which is thought to signify a neurodegenerative disorder at the early stages), the MMSE displayed questionable sensitivity. Specifically, among these studies, the percent of those suffering from MCI who fell below the most optimal MMSE cut off score ranged from 45 to 77 percent (Cruz-Orduna et al., 2012; Cullen et al., 2005; Kaufer et al., 2008; Saxton et al., 2009; Tariq et al., 2006). This means that the proportion of those with MCI who were missed by the MMSE ranged from 23 to 55 percent in these studies. 

Fortunately, there are a number of neuropsychological tests that are designed to be sensitive to even subtle changes in cognitive ability associated with neurodegenerative disorders in the early stages.  These tests compare persons taking the test to those who are nearly the same age and sometimes same level of education to reduce the possibility of misdiagnosis.  A thorough neuropsychological evaluation can help detect brain diseases early, which means that intervention can take place sooner.  Prompt treatment can slow cognitive decline and delay the necessity for less desired and more costly interventions such hospitalization and/or group home placement.

References

Cruz-Orduna I., Bellon J.M., Torrero P., Aparicio, E., Sanz, A., Mula, N., Marzana, G., Begue, C., Cabezon, D., & Olazaran, J. (2012). Detecting MCI and dementia in primary care: Efficiency of the MMS, the FAQ and the IQCODE. Family Practice, 29(4), 401–6.

Cullen B., Fahy S., Cunningham C.J., Coen, R.F, Bruce, I., Greene, E., Coakley, D., Walsh, J.B., & Lawlor, B.A. (2005). Screening for dementia in an Irish community sample using MMSE: a comparison of norm-adjusted versus fixed cut-points. International Journal of Geriatric Psychiatry, 20(4), 371–6.

Kaufer D.I., Williams C.S., Braaten A.J., Gill, K., Zimmerman, S., & Sloane, P.D. (2008). Cognitive screening for dementia and mild cognitive impairment in assisted living: comparison of 3 tests. Journal of the American Medical Directors Association, 9(8), 586–93.

Saxton J., Morrow L., Eschman A., Archer, G., Luther, J., & Zuccolotto, A. (2009). Computer assessment of mild cognitive impairment. Postgraduate Medicine, 121(2), 177–85.

Sperling, R.A., Aisen, P.S., Beckett, L.A., Bennett, D.A., Craft, S., Fagan, A.M., Iwatsubo, T., Jack, C.R., & Kaye, J. (2011). Toward defining the preclinical stages of Alzheimer’s disease: Recommendations from the National Institute on Aging and the Alzheimer’s Association workgroup.  Alzheimer’s and Dementia, 7(3), 280-292.

Tariq S.H., Tumosa N., Chibnall J.T., Perry, M.H., & Morley, J.E. (2006). Comparison of the Saint   LouisUniversity mental status examination and the Mini-Mental State Examination for detecting dementia and mild neurocognitive disorder—a pilot study. American Journal of Geriatric Psychiatry, 14(11), 900–10.

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