~ Mae West
A. Behavioral Variant FTD (bvFTD)/Frontal Variant FTD (FvFTD)/Pick's/Frontotemporal Lobar Degeneration (FTLD)
bvFTD is characterized by the insidious onset of personality changes, behavioral abnormalities and poor insight. The division of frontal lobe function into three separate areas (orbitobasal, medial, and dorsolateral) offers a way to understand the clinical presentation of bvFTD. Orbitobasal involvment leads to some of the most common symptoms encountered in this disorder. These include disinhibition, poor impulse control, antisocial behavior, and stereotypical behaviors. Examples of stereotypical, or ritualized behaviors, include insisting on eating the same food at exactly the same time daily, cleaning the house in precisely the same order, or simple repetitive behaviors such as foot-tapping. Ritualized acts may also include the use of a "catch-phrase" and a change in food preference. A patient's decline in social conduct can include breaches of interpersonal etiquette and tactlessness. Verbally inappropriate sexual comments and gestures are common.
Apathy is correlated with the severity of medial frontal-anterior cingulate involvement. Dietary changes are frequent and typically take the form of overeating, i.e. hyperorality, with a preference for sweet foods. Patients also exhibit emotional blunting. Speech output is attenuated and mutism eventually develops. Echolalia and perseveration may be present.
The most common cognitive deficit in bvFTD is an impairment of executive function or working memory, which is indicative of frontal and prefrontal cortex involvement. Other frequently encountered cognitive abnormalities include attentional deficits, poor abstraction, difficulty shifting mental set, and perseverative tendencies. Deficits in planning, organization, and other aspects of executive function become universal as the disease progresses, and this reflects the involvement of the dorsolateral prefrontal cortex.
Within the clinical subtypes of bvFTD, there is marked heterogeneity of clinical presentations, often as a result of differential involvement of brain regions. Some patients are disinhibited, fatuous, purposelessly overactive, easily distracted, socially inappropriate, and lacking in concern. At the other extreme, others are bland, apathetic, inert, lacking volition, mentally rigid, and perseverative. Social behavior has been shown to be more disrupted in patients with predominantly right-hemisphere pathology. Moreover, Mc Murtray., demonstrated that patients with frontal FTD showed hypoactivity and apathy, whereas patients with temporal FTD showed hypomania-like behavior. Decreased insight was associated with right frontal hypoperfusion, while decreased hygiene and grooming with left frontal hypoperfusion. Patients with left hemisphere FTD had early speech and language difficulty but greater normal behavior, whereas patients with right hemisphere FTD had normal speech and language but more frequent inappropriate behavior.
Review the parts of the brain by clicking here.
B. Semantic Dementia (SD)
Temporal FTD, also known as semantic dementia (SD), is associated with bilateral atrophy of the middle and inferior temporal neocortex. The most common initial presentation in these patients is an abnormality of language, which includes loss of memory for words or a loss of word meaning. Patients with SD are often unaware of their difficulties with comprehension. Speech is fluent, but patients tend to use substitute phrases such as "thing" or "that". Patients lose the ability to name and understand words and to recognize the significance of faces, objects and other sensory stimuli. They also show deficits on non-verbal tasks using visual, auditory, and other modalities, suggesting that the key impairment in SD is a breakdown in conceptual knowledge rather than a specific problem with language. Working memory and autobiographical memory, at least for the recent past, tend to be preserved. However, patients with SD perform poorly on standard anterograde verbal memory tests, such as word-list learning.
Behavioral symptoms may occur early or late in the clinical course. Patients with SD may present as less apathetic and more compulsive than those with FvFTD. They may show interpersonal coldness and impairments in emotional processing. Patients with more marked right temporal lobe involvement tend to present with significant changes in personality, such as emotional disturbances, bizarre alterations in dress, and limited, fixed ideas.
Snowden et al., compared behavioral patterns and functional imaging in patients with FTD to those with SD. Whereas lack of emotional responsiveness was pervasive in FTD, it was often more selective in semantic dementia and particularly affected the capacity to show fear. Apathetic FTD patients also had a higher pain threshold, whereas patients with SD had an exaggerated response to pain. Overall, emotional, repetitive, and compulsive behaviors discriminated FTD from SD with an accuracy of 97%.
C. Progressive aphasia (PNFA)
Progressive non-fluent aphasia (PNFA) is a disorder predominantly of expressive language, in which severe problems in word retrieval occur in the context of preserved word comprehension. This disorder is associated with asymmetric atrophy of the left hemisphere. Patients present with changes in fluency, pronunciation, or word finding difficulty. They do not present with behavioral problems until later in the disease. In a study that assessed discourse in patients with both semantic dementia and PNFA, patients with PNFA had the sparsest output producing narratives and had the fewest words per minute.
This was just a short article I found which addressed the differences in the various forms of FTD. I found it to be a good review in a short amount of space. It is important to always keep in mind that every case of FTD is different. Everybody does not have to have all of the symptoms listed, and some of them may never develop. Though current research is correlating parts of the brain affected with behavior, nobody knows much about it yet.
Everything here is my account of what happened to me, or my interpretation of stuff, except what I copied from somewhere else. Wikepedia is a constant source of information. Every case of FTD is different. Keep in mind as you read this that the person who wrote this has dementia. That would be ME.
Questions and comments are welcome.