Pick Disease 

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. (See Etiology.)

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. (See Presentation and Workup.)^{[1, 2]}

Frontotemporal dementia

Pick disease is one of the disorders classified under the term frontotemporal dementia (FTD). Almost all instances can be pathologically classified by abnormal deposited proteins in cells: (1) the tau-positive type, marked by loss of cortical neurons, with minimal microvacuolation and related gliosis; (2) associated with progranulin (FTD-TDP), marked by neuronal cytoplasmic inclusions and, frequently, intranuclear inclusions, as well as variable dystrophic neurites, in frontotemporal cortex; and (3) associated with fused-in-sarcoma (FUS) protein (neuronal intermediate filament inclusion disease, basophilic inclusion body disease, or atypical, with ubiquitin-only immunoreactive changes).^[3] (See Etiology and Workup.)

FTD with abnormal tau protein accumulation has been associated with mutations at chromosome 17; TDP-43 associations are linked to band 9p; ubiquinated FUS accumulation is still under intense investigation; other mutations (CHMP-2B) are also identified in rarer cases.

Primary progressive aphasia is a focal atrophy syndrome that may be associated with Pick disease, Alzheimer disease, or other pathology. Clinically, the deficit appears restricted to the frontal and/or temporal lobes.^[4] Behavioral-variant FTD is the other major FTD syndrome; in this disorder, deficits are nonverbal and primarily affect social, emotional, and self-regulatory skills.

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

Cellular characteristics

Pick disease is defined pathologically by severe atrophy, neuronal loss, and gliosis. Frequently, Pick disease is accompanied by the occurrence of tau-positive inclusions.^[5] Swollen (ballooned) neurons (Pick cells) and argentophilic neuronal inclusions, known as Pick bodies,^[6] can disproportionally affect the frontal and temporal cortical regions. (See Workup.)

Fewer Pick bodies may be present in these regions if the primary symptoms are behavioral (behavioral variant), compared with the primary symptoms of aphasia.^[7]

In a clinicopathologic series, only 5% of patients with clinically diagnosed frontotemporal dementia had classic Pick disease with Pick bodies at postmortem evaluation. (See Epidemiology.)^[8]

Patient education

For patient education information, see the Brain and Nervous System Center, as well as Pick Disease and Dementia Medication Overview.

The specific cause of Pick disease is unknown. As many as 50% of patients with frontotemporal dementia have a positive family history of dementia and inherit frontotemporal dementia as an autosomal dominant trait with high penetrance.^[3]

In families with an inherited frontal lobe dementia (some of which have been found to be pathologically or clinically indistinguishable from Pick disease), linkage to markers on chromosomes 17, 9, and 3 have been reported.

These familial disorders are heterogenous in different family members. Some members may present primarily with amyotrophy, and others may present with primary supranuclear gaze palsy, parkinsonism, schizophrenialike thought disorder, or progressive aphasia and/or apraxia.

Occurrence in the 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, with Alzheimer disease becoming 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 pathologic substrates, the most prevalent of which is frontotemporal lobar degeneration with ubiquitin inclusions. In one pathologic series, 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.^[8]

International occurrence

Familial forms of Pick disease may occur more frequently in Europe (particularly in Scandinavian nations). The estimated frequency ranges from 7-43 cases per 100,000 population.^[9] In a study in the Netherlands, the prevalence was 28 per 100,000 persons.^[3]

Like most dementias, Pick disease is slowly progressive, leading to increased vocational and personal disability. However, a small number of people who have behavioral disturbance consistent with the behavioral variant of FTD may not progress—this has been called the phenocopy variant. In past studies, slow or no progression occurs only in patients with nonlinguistic symptoms—none had primary progressive aphasia.

Some patients can progress slowly over extremely long periods. Some may develop artistic or other talents during the course of their dementia, a phenomenon that is perhaps related to disinhibition of "creative" brain areas. Musical or artistic tastes also may change (eg, the patient may develop a sudden interest in music intended for much younger listeners).

Some patients may be capable of acquiring new knowledge or skills, such as the use of a computer-assisted, simple communication system. This relative sparing of ability to “do things” (process-oriented rather than content-oriented memory) may be helpful in implementing behavioral training techniques to optimize social and daily activity competence.

Race-, sex-, and age-related demographics

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 this population. [#IntroductionAge]

Pick disease occurs in a younger age group than dementia of the Alzheimer type, with peak incidence occurring in individuals aged 55-65 years. More men than women may be affected by Pick disease.^{[10, 11]}

Morbidity and mortality

Pick disease runs a shorter course than Alzheimer disease, on average about 6 years.^{[10, 12]} In some individuals whose main symptoms are a disturbance of speech and language (primary progressive aphasia), the clinical course can be slow. In one small series, these patients survived an average of 5 years longer than patients with behavioral symptoms (behavioral variant).^[7] A patient with primary progressive aphasia may preserve the ability to function at home for 10 or more years after onset.