Frontotemporal dementia is a term encompassing a group of dementias associated with progressive atrophy of the temporal lobe, frontal lobe, or both. Principal symptoms include behavioral disinhibition and personality changes, as well as deficits in language, both in speech production and word comprehension. The diagnosis can be made only after a thorough clinical and imaging workup.
Identified as the second most common type of early-onset dementia and responsible for approximately 10-20% of all dementias, frontotemporal dementia (FTD) is characterized by a progressive neuronal loss in the frontal and temporal lobes . FTD appears at a rate of 3-15 per 100,000 individuals between 55-65 years of age and affects both sexes almost equally . Several distinct clinical syndromes have been described in the literature      :
- Behavioral-variant frontotemporal dementia (bvFTD) - Considered as the most common form of FTD (presumably caused by genetic mutations), this subtype is responsible for about 50% of all cases and is distinguished by various changes in personality and behavior due to loss of neuronal circuits in the frontal lobe  . Disinhibition is the most prominent feature manifested as inappropriate social behavior (insensitive remarks to others, inclination toward violence, assault, excessive eating, hypersexual and sociopathic behavior), absence of empathy, lack of insight and awareness, abnormal behavioral patterns regarding their thoughts or habits, as well as a lack of personal hygiene and sphincter control are present in the majority of patients   . About 50% of bvFTD patients show either probable or possible signs of amyotrophic lateral sclerosis (ALS, which may develop together with all other forms of FTD, but much rarely as comapred to bvFTD). In that case, symptoms of motor neuron disease are present   .
- Semantic dementia (SD) - Progressive neuronal loss in the anterior temporal lobes is the main pathological entity described in SD, consequently leading to aphasia and loss in semantic memory (presenting as the inability to attach words with objects and an overall loss of vocabulary)   . As a result, patients interact by using nonspecific words and imprecise terms, while agnosia and prosopagnosia (inability to recognize visual objects or familiar faces, respectively), as well as behavioral disturbances seen in bvFTD, develop in later stages of the disease    .
- Progressive non-fluent aphasia (PNFA) - Agrammatism, apraxia (difficulties in speech initiation), dysarthria, and a slow speech full of errors are main characteristics of this type of FTD.
- Overlap syndromes - Some authors have confirmed overlapping of FTD and two clinical syndromes - corticobasal syndrome (CBD) and supranuclear palsy (in addition to ALS). Deficits in vertical gaze, postural instability, ophthalmoplegia and disinhibitory symptoms suggest an association of FTD with supranuclear palsy, whereas apraxia, rigidity, and myoclonus indicate CBD as the overlapping syndrome   .
Entire Body System
- Abnormal Behavior
Researchers looked at when the dementia symptoms began based on the earliest report from family members telling of persistently abnormal behavior. Survival was defined as from the time symptoms began until death. [psychcentral.com]
behavioral patterns regarding their thoughts or habits, as well as a lack of personal hygiene and sphincter control are present in the majority of patients. [symptoma.com]
Their interest in sex may increase abnormally. Behavior may become impulsive and compulsive. They may repeat the same action over and over. They may walk to the same location every day. [merckmanuals.com]
- Inappropriate Sexual Behavior
Examples include shoplifting, encroaching on someone’s personal space, and inappropriate sexual behavior. Social skills like tact and empathy may be lost. They may lose interest in everything, or they may suddenly need to be active all the time. [dementiacarecentral.com]
- Motivation Decreased
decrease in energy, and generally compulsive behavior. [disabilitybenefitscenter.org]
- Disorganized Behavior
At the age of 58, the patient had a sudden onset of disorganized behavior and meaningless speech. Psychotropic drugs were effective for catatonic symptoms. [ncbi.nlm.nih.gov]
- Auditory Hallucination
RESULTS: Detailed histories revealed a higher prevalence of psychosis, including visual and auditory hallucinations and delusions, in the 8 C9ORF72 carriers than in our patients with sporadic FTD. [ncbi.nlm.nih.gov]
These possibilities include: Behavioral variant FTD – these patients have prominent, early changes in their behavior (such as being more impulsive or irritable), social interaction with others (kissing strangers, crude or explicit remarks), initiative [alzheimers.emory.edu]
[…] most common symptoms of bvFTD are behavioral or emotional challenges, including compulsively overeating, having an emotionally-detached demeanor, making socially inappropriate responses, and displaying hypersexual conversation and actions, along with irritability [alzheimers.about.com]
Personality changes can also involve increased irritability, anger and even verbal or physical outbursts toward others (usually the caregiver). [brain.northwestern.edu]
There are medications that can reduce agitation, irritability and/or depression. These treatments should be used to help improve quality of life. [alz.org]
- Memory Impairment
The second patient presented with progressive memory impairment and marked personality changes after a transient ischaemic attack. [ncbi.nlm.nih.gov]
In both FTLD groups, memory impairment was present, as indicated by the collateral source or the participant. This deficit, however, was universal in those with AD. [dx.doi.org]
Memory impairment is not an initial symptom, and yet those with PPA/FTD who are in the earlier stages may be perceived by others as having Alzheimer’s disease. [crisisprevention.com]
Catatonia is a clinical syndrome characterized by symptoms such as immobility, mutism, stupor, stereotypy, echophenomena, catalepsy, automatic obedience, posturing, negativism, gegenhalten and ambitendency. [ncbi.nlm.nih.gov]
These may include simple actions (grunting, hand rubbing, foot tapping); rituals relating to toileting or dressing; wandering and pacing in a fixed route; perseverative responses and stereotyped use of words and phrases 3 ; superstitious rituals (avoiding [doi.org]
Evaluation of patients in whom dementia of any type is suspected must start with a comprehensive history and a thorough physical examination, both being equally important. Physicians should suspect FTD if they detect language deficits and disinhibitory symptoms (which are often noticed by friends or family members, but not by the patients themselves), and if the patients are somewhat younger than the known age for the onset of dementia ( i.e.< 65 years of age). A complete neurological exam (to assess whether motor neuron disease is concomitantly present) and cognitive testing, an integral component in the assessment of dementia, provides vital clues to differentiate between various forms of FTD  . Imaging studies, however, are necessary to rule out other causes of such symptoms (eg. tumors), and magnetic resonance imaging (MRI) is the recommended method    . Atrophy of the frontal and temporal lobes are present, with the dorsolateral prefrontal cortex being involved in the majority of cases  . In addition, the anterior cingulate, orbitofrontal and frontoinsular cortices are commonly affected, often correlating with the extent of manifested symptoms . If findings on MRI are inconclusive, then single photon emission computed tomography (SPECT) or fluorodeoxyglucose positron emission tomography (FDG-PET) are recommended due to their ability to detect dysfunction of specific areas of the brain .
- Ferrari R, Hernandez DG, Nalls MA, et al. Frontotemporal dementia and its subtypes: a genome-wide association study. Lancet neurology. 2014;13(7):686-699.
- Warren JD, Rohrer JD, Rossor MN. Frontotemporal dementia. BMJ. 2013;347:f4827.
- Rabinovici GD, Miller BL. Frontotemporal Lobar Degeneration: Epidemiology, Pathophysiology, Diagnosis and Management. CNS drugs. 2010;24(5):375-398.
- Tsai RM, Boxer AL. Treatment of Frontotemporal Dementia. Curr Treat Options Neurol. 2014;16(11):319.
- Goedert M, Ghetti B, Spillantini MG. Frontotemporal Dementia: Implications for Understanding Alzheimer Disease. Cold Spring Harb Perspect Med. 2012;2(2):a006254.
- Arvanitakis Z. Update on Frontotemporal Dementia. The neurologist. 2010;16(1):16-22
- Forman MS, Farmer J, Johnson JK, et al. Frontotemporal Dementia: Clinicopathological Correlations. Annals of neurology. 2006;59(6):952-962.