Frontotemporal dementia

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Frontotemporal dementia.
Classification and external resources

A human brain showing frontotemporal lobar degeneration (right), which causes frontotemporal dementia
ICD-10G31.0
ICD-9331.19
OMIM600274 105550 614260
DiseasesDB10034
MeSHD003704
GeneReviews
 
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Frontotemporal dementia.
Classification and external resources

A human brain showing frontotemporal lobar degeneration (right), which causes frontotemporal dementia
ICD-10G31.0
ICD-9331.19
OMIM600274 105550 614260
DiseasesDB10034
MeSHD003704
GeneReviews

Frontotemporal dementia (FTD) is the clinical syndrome caused by degeneration of the frontal lobe of the brain. The degeneration can extend to the temporal lobe. FTD is the clinical manifestation of frontotemporal lobar degeneration, and the second most common pre-senile dementia after Alzheimer's disease.[1]

Contents

Signs and symptoms

FTD is traditionally difficult to diagnose due to the heterogeneity of the condition. This heterogeneity means the signs and symptoms can vary dramatically between patients. Symptoms are classified into three groups which underlie the functions of the frontal and temporal lobes:

Recent studies indicates that patients that are diagnosed with FTD tend to overeat which results to binge eating.[4] These binge eating habitats are often associated with abnormal eating behavior including overeating, stuffing food, changes in food preferences (cravings for more sweets, carbohydrates), eating inedible objects and snatching food from others. Recent findings have indicated that the neural sturctures responsible for eating changes in FTD has been linked with atrophy in the right ventral insula, striatum and orbitofrontal cortex on structural MRI voxel-based morphometry (right hemisphere).[4]

Executive function is the cognitive skill of planning and organizing. Most FTD patients become unable to perform skills that require complex planning or sequencing.[5] In addition to the characteristic cognitive dysfunction, a number of primitive reflexes known as frontal release signs are often able to be elicited. Usually the first of these frontal release signs to appear is the palmomental reflex which appears relatively early in the disease course whereas the palmar grasp reflex and rooting reflex appear late in the disease course.

FTD can occur in patients with motor neuron disease (typically amyotrophic lateral sclerosis) in a small number of cases. The prognosis for people with MND is worse when combined with FTD, shortening survival by about a year.[6]

Pathology

A number of case series have now been published looking at the pathological basis of frontotemporal dementia. As with other syndromes associated with frontotemporal lobar degeneration (FTLD), a number of different pathologies are associated with FTD:

Diagnosis

According to DSM-IV diagnosis is mainly clinical including changed behaviors, changes in language and others, using also image exams and neuropsychological tests.[9]

Structural MRI scans often reveal frontal lobe and/or anterior temporal lobe atrophy but in early cases the scan may seem normal. Atrophy is often asymmetric. Registration of images at different time points (e.g. one year apart) can show evidence of atrophy in two cross-sectional images that may be reported as normal. This is a useful diagnostic technique. However, many research groups are currently looking at ways of making an early diagnosis of FTD using other techniques (magnetic resonance spectroscopy, functional imaging, cortical thickness measurements etc.). FDG-PET scans classically show frontal and/or anterior temporal hypometabolism, which helps differentiate from Alzheimer's disease. The PET scan in Alzheimer's disease classically shows biparietal hypometabolism. Meta-analyses based on imaging methods have shown that frontotemporal dementia mainly affects a frontomedian network discussed in the context of social cognition or 'theory of mind'.[10] This is entirely in keeping with the notion that, on the basis of cognitive neuropsychological evidence, the ventromedial prefrontal cortex is a major locus of dysfunction early on in the course of the behavioural variant of frontotemporal degeneration.[11] The language subtypes of frontotemporal lobar degeneration (semantic dementia and progressive nonfluent aphasia) can be regionally dissociated by imaging approaches in vivo.[12]

Through recent findings it has been suggested that vivo brain imaging of tau aggregation in frontal temporal dementia using [F-18] FDDNP Positron Emission Tomography is more visual and has enhanced the ability to have a deeper understanding in frontal temporal dementia. Previous, fluorescent microscopy studies of Alzheimer’s disease (AD) brain specimens have shown that [F-18] FDDNP, displays and excellent visualization of interneurnnal neurofibrillary tangles (NFTs). With the aid of [F-18]FDDNP depicts that it is useful in imaging frontal temporal dementia. Visual images of [F-18] FDDNP-PET images emphasized a frontal signal in FTD compared to prominent temporal signals in AD. [F-18]FDDNP-PET has allowed the enhance visualization of tauopathies in patients. This has aided in differentiating FTD from parietal and temporal signals in AD. Further, the ability of [F-18] FDDNP to entitle tanopathies in vivo gives a tool for monitoring the effect of therapies to eliminate NFT accumulation.[13]

Genetics

A higher proportion of FTD cases seem to have a familial component than more common neurodegenerative diseases like Alzheimer's disease. More and more mutations and genetic variants are being identified all the time, so the list of genetic influences below may be outdated.

Management

There is no known curative treatment for FTD. Supportive care is essential. Management of behavioural symptoms may be necessary (e.g. SSRIs for depression; atypical neuroleptics etc.).

Because FTD often occurs in younger people (i.e. in their 40's or 50's), it can severely affect families. Patients often still have children living in the home. Financially, it can be devastating as the disease strikes at the time of life that is often the top wage-earning years.[citation needed]

Prognosis

Median survival time is 7 years.[16]

See also

References

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  2. ^ Mendez MF, Shapira JS, Woods RJ, Licht EA, Saul RE (2008). "Psychotic symptoms in frontotemporal dementia: prevalence and review". Dement Geriatr Cogn Disord 25 (3): 206–11. doi:10.1159/000113418. PMID 18204254. http://content.karger.com/produktedb/produkte.asp?DOI=10.1159/000113418.
  3. ^ Hodges, R. John. 1999. "Neuropsychology: The Differentiation of Semantic Dementia and Frontal Lobe Dementia. pg. 31-49
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  6. ^ Olney RK, Murphy J, Forshew D, et al. (December 2005). "The effects of executive and behavioral dysfunction on the course of ALS". Neurology 65 (11): 1774–7. doi:10.1212/01.wnl.0000188759.87240.8b. PMID 16344521. http://www.neurology.org/cgi/pmidlookup?view=long&pmid=16344521.
  7. ^ Liscic RM, Storandt M, Cairns NJ, Morris JC (April 2007). "Clinical and psychometric distinction of frontotemporal and Alzheimer dementias". Arch. Neurol. 64 (4): 535–40. doi:10.1001/archneur.64.4.535. PMID 17420315. http://archneur.jamanetwork.com/article.aspx?doi=10.1001/archneur.64.4.535.
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  9. ^ Demencia frontotemporal y enfermedad de motoneurona
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  13. ^ Small, Gary; Vladimir Kepe, Sung C. Huang, H.M. Wu, Prabha Siddarth, Linda Ercoli, Karen Miller, Helen Lavretsky, Benjamin C. Wright, Kooresh Shoghi-Jadid, Nagichettiar Satyamurthy, Michael E. Phelps, Jorge R. Barrio (July 2004). "In Vivo Brain Imaging of Tau Aggregation in Frontal Temporal Dementia Using [F-18]FDDNP Positron Emission Tomography". Neurobiology of Aging. 2 25 (26): 288-289.
  14. ^ Luc Buée; André Delacourte (1999). "Comparative biochemistry of tau in progressive supranuclear palsy, corticobasal degeneration, FTDP-17 and Pick's disease.". Brain Pathology 9 (4): 681–693. doi:10.1111/j.1750-3639.1999.tb00550.x. PMID 10517507. http://pagesperso-orange.fr/alzheimer.lille/pdf/1999/1999BueeBrainPathol.pdf.
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Liu, W (1 March 2004). "Behavioral disorders in the frontal and temporal variants of frontotemporal dementia". Journal of Neurology. 5 62: 742-748. doi:10.1212/01.WNL.0000113729.77161.C9.

Hodges, J.R (2 April 2003). "A study of stereotypic behaviours in Alzheimer’s disease and frontal and temporal variant frontotemporal dementia". Neurol Neurosurg Psychiatry 74 (10): 1398 - 1402. doi:10.1136/jnnp.74.10.1398.

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