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Pick's disease is a rare neurodegenerative disorder that causes the atrophy, or gradual wasting away, of the frontal and temporal lobes of the brain, which are responsible for higher cognition, speech and vision processing, and long-term memory. It is characterized by the destruction of nerve cells in the brain and the accumulation of tau proteins, a normally occurring protein in neurons of the central nervous system, into concentrations known as "Pick bodies." Pick's disease is named after German neurologist and psychiatrist Arnold Pick, who discovered the pathology in 1892. It is unknown what causes Pick's disease, but no genetic basis has been identified.
Pick's disease is one of many pathologies that can cause frontotemporal lobar degeneration. There are three different manifestations of frontotemporal lobar degeneration: frontotemporal dementia, progressive nonfluent aphasia, and semantic dementia. Semantic dementia is less associated with Pick's disease than the other subtypes.
Frontotemporal dementia causes two types of symptoms: behavioral symptoms and loss of executive function. Behavioral symptoms can include personality change, either apathy and extreme lethargy, or inappropriate behavior due to complete disinhibition. A patient may become unable to take basic care of himself or herself, or may indulge in risky and socially unacceptable behavior such as openly sexual comments or theft. Loss of executive function is characterized by difficulty in performing tasks that involve complex planning and often manifests through language impairment.
Progressive nonfluent aphasia is a type of language impairment in which the patient exhibits difficulty speaking. This impairment can take many forms. The patient may exhibit apraxia, or difficulty forming speech sounds, or may develop a stutter. Other possible forms include anomia, an inability to recall names or nouns; agrammatism, or the inability to speak with normal word order and verb tenses; and phonemic paraphasia, in which the patient uses the wrong consonant or vowel sounds in his or her speech. A patient with progressive nonfluent aphasia may exhibit one or many of these symptoms, and the impairment worsens over time.
Semantic dementia was first described by Arnold Pick in 1904, but is not caused by Pick's disease as often as the other two forms of frontotemporal lobar degeneration. Semantic dementia is characterized by an inability of the patient to remember the meanings of words and visual cues. A patient suffering from semantic dementia may exhibit anomia and impaired comprehension of the speech of others. He or she may also be unable to match semantically related images or may frequently call things by the wrong name.