Concomitant pathologies II : neurodegenerative conditions

• Introduction The term “mixed or concomitant” pathologies in neurodegenerative disease means that, in addition to the hallmark lesions of a neurodegenerative disease entity, further pathological alterations can be observed in the same brain. The term mixed pathology was originally used when describing accompanying vascular pathology. Later, Lewy body pathology was also described as concomitant pathology when seen together with other neurodegenerative diseases. Currently, we classify neurodegenerative diseases according to the predominant protein that shows pathological depositions in the brain. During the diagnostic process, detecting hallmark lesions of a certain disease, like neuritic plaques in the cortex, spongiform change in the cortex, globose tangles in the brainstem nuclei or Lewy bodies in the brainstem or cortex, can lead to negligence of further lesions or performance of further stains. However, deposition of multiple proteins, in addition to co-occurrence of non-neurodegenerative pathology (e.g. vascular, metabolic), is a frequent event. In fact, overlapping neurodegeneration may be more the rule than the exception. This concept is supported by observations in genetic forms of neurodegenerative disorders where various proteins may show pathological deposits in the same brain [1–3]. Complex constellations of clinical symptoms (movement disorders and cognitive decline) may associate with the accompanying presence of diverse neurodegenerative disorders. There are several factors determining overlap between neurodegenerative disorders as proposed by Armstrong et al. [4]): (i) historical factors, which means that the original descriptions of key disorders were based on the descriptions of relatively small numbers of cases; furthermore, the original investigators interpreted these as ‘syndromes’ rather than distinct diseases; (ii) disease heterogeneity; (iii) age-related changes;(iv) apolipoprotein ɛ genotype, especially in cases with significant Aβ deposition but without further features of Alzheimer’s disease (AD); (v) co-occurrence of common diseases, like AD and Parkinson’s disease (PD), as both are more likely to occur in the elderly and thus are more likely to co-occur.

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MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Klinisk laboratoriemedicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Clinical Laboratory Medicine (hsv//eng)

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Patologi

Pathology

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