What is Pick disease?
Pick disease is a rare neurodegenerative disease that causes dementia or memory loss in patients. In a neurodegenerative disease, nerve cells (neurons) in the brain die and this results in irreversible damage. Pick disease results in aphasia (impaired ability to speak) and behavioral changes. This disorder affects emotional, social, and self-control skills of the patients. Unlike another similar brain condition known as Alzheimer’s disease, which affects individuals mostly after 50 years of age, Pick disease occurs in adults in their 40s. It affects men more often than women.
Pick disease (abbreviated as PiD) affects specific brain areas known as the frontal and temporal lobes. A problem in these brain regions results in frontotemporal dementia (FTD) because both these regions are important for the maintenance of different types of memory, including long term memory and verbal memory.
Picture from Wikimedia Commons
How common is Pick disease?
Pick disease is a rare disorder. In United States, Pick disease accounts for 5% of all the cases of frontotemporal dementias. Pick disease may run in some families in Scandinavian nations, where it might affect more than 40 persons in every 100,000.
Brain changes in Pick disease
In Pick disease, the neurons of the cortex or the outer layer of brain die due to accumulation of an abnormal protein called tau. Deposition of Tau protein in the neurons damages these cells irreversibly. Loss of neurons leads to shrinkage of the frontotemporal areas of the brain.Tau proteins are found in normal neurons as well. These proteins stabilize other proteins that form the cellular skeleton. However, a defect in Tau proteins leads to dementia.
In Pick disease, the defective Tau proteins aggregate to form spherical bodies called pick bodies. When the affected neurons (also called pick cells) are stained with specific dyes, these pick bodies look like large, dark balloons. In the brains of patients with Pick disease, some of the non-neuronal cells known as astrocytes grow abnormally to form a dense fibrous network. This leads to a scar or gliosis, which is one of the characteristic features of Pick disease.
Pick Disease Symptoms
Inappropriate behavior in social setting is one of the major symptoms of Pick disease, and is not significantly different from other neurodegenerative diseases. For friends and family of the patient, it is often among the more disturbing of symptoms. These issues with behavior worsens over time as the condition progresses.
Patients with Pick disease may show any of the following symptoms:
- Increased aggression, irritability and agitation
- Socially inappropriate behaviors
- Obsessive or repetitive behaviors
- Frequent mood swings
- Indifferent and apathetic attitude
- Lack of self-monitoring
- Problems in self-awareness
- Difficulty with decision-making
- Unable to fathom importance or meaning of topics
- Changes in eating habits
- Increased appetite
- Problems in speech and language abnormalities
- Problems with memory
- Repeating and imitating others’ words and actions
- Difficulty naming common objects (anomia)
- Urinary incontinence
- Indifference towards personal hygiene
- Shrinking vocabulary
Complications of Pick disease
Pick disease progresses rapidly in comparison to other neurodegenerative disorders. However, it can be difficult to recognize the onset of the behavioral symptoms. The disease causes irreversible damage to neurons and severely affects the quality of life. Patients with Pick disease become totally disabled even in the early stages of the disease.
Pick’s disease causes death within 2 to 10 years. Death may result from infection or from general failure of the body systems.
Some patients with Pick disease may exhibit pooling of blood on the surface of the brain (subdural hematoma) when CSF samples are taken from them for laboratory tests. This can cause headaches and change in mental status of the patients.
Other complications may include:
- Increased risks of infection
- Loss of ability to care for self
- Loss of ability to interact with others
- Loss of ability to function in daily activities
- Side effects of medications used to treat the disorder
Causes of Pick disease
The cause of Pick disease is not fully understood. Since the disease seems to run in some families, a mutated gene might be responsible for this phenomenon. There are no clearly identifiable risk factors that can be attributed to Pick disease beyond the familial tendency.
Diagnosis and Tests
The following tests can be used for diagnosing Pick disease:
- Lab tests: To rule out other causes of dementia, blood samples can be tested to determine the levels of vitamin B and ceruloplasmin, thyroid and liver functions, unusual antibodies called antinuclear antibodies, and for the presence of syphilis. In Pick disease, cerebrospinal fluid (CSF) surrounding the brain and the spinal cord may show the presence of Tau proteins.
- Imaging studies: A computed tomography (CT) or magnetic resonance imaging (MRI) scan can detect shrinkage of the frontotemporal areas of the brain.
- Cognitive examinations: Cognitive (related to mental abilities) deficits are common in patients with Pick disease. Visuospatial functions (abilities to perceive objects and their relative positions in space) are not affected in such patients. There are also distinct problems with syntax and fluency while speaking.
Pick disease treatment
There is no cure for Pick disease. Treatment aims to protect the patient’s neurological functions and treat the symptoms.
- Drugs such as sedatives, benzodiazepines, and anti-cholinergics should be stopped or changed because these drugs may impair memory or cause confusion.
- Depending on the symptoms, drug prescriptions may include vitamins, cholinergic or dopaminergic agents, or antidepressants.
- Antidepressants like selective serotonin reuptake inhibitors (SSRIs) may control some behavioral symptoms in these patients. However, these medications may cause adverse effects like movement disorders (dyskinesias) and restless leg syndrome (akathisia) in some patients.
- Mirtazapine may be used to control agitation, depression and disinhibition in some patients. However, it also has a sedative effect.
- Venlafaxine can be given to patients who are unable to make decisions or act independently. Ergot derivatives (like bromocriptine) may also be given for the same purpose; however, these agents may worsen the behavioral problems in patients of Pick disease.
- Trazodone is effective in decreasing agitation in the patients.
- Drugs called acetylcholinesterase inhibitors may help those patients who exhibit difficulty in speaking.
- Dopamine agonists, like amantadine may help patients with restless legs syndrome.
- Depending on the severity of the symptoms, the patients may need monitoring, help with personal hygiene, self-care, and day-to-day activities.
Pick disease prognosis
Pick disease leads to disability of social and behavioral skills. The duration of progression of the disease may vary in different patients – the condition may worsen rapidly in some patients, whereas others may get affected over very long periods.
Interestingly, some patients develop artistic or other talents during the progression of dementia in Pick disease. It might be the result of disinhibition of creative brain areas. Some patients may acquire new knowledge or skills. These skills may improve their competence in performing social and daily activities.