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Frontotemporal dementia (FTD) is the clinical presentation of frontotemporal lobar degeneration, which is characterized by progressive neuronal loss predominantly involving the frontal and/or temporal lobes, and typical loss of over 70% of spindle neurons, while other neuron types remain intact.〔(【引用サイトリンク】title=Brain Cells for Socializing )〕 It was first described by Arnold Pick in 1892 and was originally called "Pick's disease", a term now reserved for Pick disease, one specific type of frontotemporal dementia.〔 Second only to Alzheimer's disease (AD) in prevalence, FTD accounts for 20% of young onset dementia cases. Signs and symptoms typically manifest in late adulthood, more commonly between the ages of 55 and 65, approximately equally affecting men and women.〔 Common signs and symptoms include significant changes in social and personal behavior, apathy, blunting of emotions, and deficits in both expressive and receptive language. Currently, there is no cure for FTD, but there are treatments that help alleviate symptoms. ==Signs and symptoms== FTD is traditionally difficult to diagnose due to the heterogeneity of the associated symptoms. Signs and symptoms are classified into three groups based on the functions of the frontal and temporal lobes: *Behavioural variant frontotemporal dementia (BvFTD) is characterized by changes in social behavior and conduct, with loss of social awareness and poor impulse control. *Semantic dementia (SD) is characterized by the loss of semantic understanding, resulting in impaired word comprehension, although speech remains fluent and grammatically faultless.〔 *Progressive nonfluent aphasia (PNFA) is characterized by progressive difficulties in speech production.〔 However, the following abilities in the person with FTD are preserved:〔 *Perception *Spatial Skills *Memory *Praxis In later stages of FTLD, the clinical phenotypes may overlap.〔 FTD patients tend to struggle with binge eating and compulsive behaviors. These binge eating habits are often associated with abnormal eating behavior including overeating, stuffing oneself with 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 structures responsible for eating changes in FTD include atrophy in the right ventral insula, striatum and orbitofrontal cortex on structural MRI voxel-based morphometry (right hemisphere).〔 Executive function is the cognitive skill of planning and organizing. Most FTD patients become unable to perform skills that require complex planning or sequencing. 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. In rare cases, FTD can occur in patients with motor neuron disease (MND) (typically amyotrophic lateral sclerosis). The prognosis for people with MND is worse when combined with FTD, shortening survival by about a year.〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Frontotemporal dementia」の詳細全文を読む スポンサード リンク
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