Excerpt from Pick Disease

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Background

Pick disease (named after Arnold Pick) is a progressive dementia defined by clinical and pathologic criteria. Unlike Alzheimer disease, which typically presents with impairment of recent memory associated with entorhinal cortex and hippocampal dysfunction, Pick disease typically affects the frontal and/or anterolateral temporal lobes. First described in 1892, with the defining pathologic characteristics first reported by Alois Alzheimer in 1911, Pick disease is now considered by some to be part of a "complex" of neurodegenerative disorders with similar or related histopathologic and clinical features.^{1, 2}

Nomenclature history

Frontotemporal dementia (of which Pick disease is an example) is a broader term including Pick disease. Frontal lobe dementia is a term signifying neuropsychological features localizing to the frontal lobes. Clinically, Pick disease may be identical or very similar to frontal lobe degeneration.³

Some cases diagnosed premorbidly as Pick disease are shown pathologically to be progressive subcortical gliosis.⁴ Other cases may be diagnosed pathologically as dementia lacking distinctive histopathology.⁵ A clinical/genetic nosology includes frontotemporal dementia linked to chromosome 17.⁶ Primary progressive aphasia is a focal atrophy syndrome that may be associated with Pick, Alzheimer, or other pathology; clinically the deficit appears restricted to the frontal and/or temporal lobes.⁷

In a recent clinicopathological series, only 5% of patients with clinically diagnosed frontotemporal dementia had classical Pick disease with Pick bodies at postmortem evaluation.⁸

Pathophysiology

Pick disease is defined pathologically by severe atrophy, neuronal loss, and gliosis. Classified as a tauopathy, Pick disease is always accompanied by the occurrence of tau-positive inclusions.⁹ Swollen (ballooned) neurons (Pick cells) and argentophilic neuronal inclusions known as Pick bodies^{10, 11} disproportionally affect the frontal and temporal cortical regions.

Images of these abnormal findings can be viewed online at Internet Pathology Laboratory, University of Utah, CNS Degenerative Diseases.

Frequency

United States

Frontotemporal dementias as a group are the fourth most common cause of dementia. In most parts of the United States, among patients younger than 60 years, the frontotemporal dementias are the first or second most common cause of dementia. In patients older than 60 years, the incidence and prevalence of Alzheimer disease begins to take off and Alzheimer disease becomes by far the most prevalent form of dementia.⁸

Pick disease is sometimes used to refer to the clinical phenotype of the frontotemporal dementias. This group of disorders has a variety of pathological substrates, the most prevalent is frontotemporal lobar degeneration with ubiquitin inclusions. Pick disease itself (as defined by the presence of tau-positive, silver staining, cytoplasmic inclusions) accounted for only 5% of all cases of frontotemporal dementias in a recent pathological series.⁸

International

Familial forms of Pick disease may occur more frequently in Europe (particularly in Scandinavian nations). In a recent study in the Netherlands, the prevalence was only 28 per 100,000 persons.¹²

Mortality/Morbidity

• The disorder is progressive and invariably leads to increasing disability. The disease runs a shorter course than Alzheimer disease, on average about 6 years.^{13, 14}
• In some individuals whose main symptoms are a disturbance of speech and language (primary progressive aphasia), the clinical course can be slow. The patient's ability to function at home may be spared for 10 or more years after onset.

Race

• Familial forms of Pick-complex dementias, linked to chromosome arm 17q, may be particularly common in people of Scandinavian origin/descent.
• It may represent as many as 17% of dementias in these populations.

Sex

More men than women may be affected.^{13, 15}

Age

• Pick disease occurs in a younger age group than dementia of the Alzheimer type.
• Peak incidence occurs in individuals aged 55-65 years, and in most patients, Pick disease often presents when younger than 70 years.

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