Frontotemporal dementia is also a relatively common cognitive disorder, and the rate of consultation has been increasing in recent years. Since the onset of the disease is earlier than that of Alzheimer’s disease (commonly known as senile dementia) and vascular dementia, and the burden on individuals and families is relatively heavier, it is necessary to introduce some basic concepts of the disease here. Frontotemporal dementia (FTD), also known as frontotemporal lobe degeneration (FTLD), is a group of diseases characterized by behavioral and personality changes and aphasia. According to the American epidemiological survey and pathological classification, FTLD is the third type of dementia after Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB). The age of onset is 45-70 years, with the vast majority of patients developing the disease before the age of 65. The duration of the disease is 2 to 20 years, with an average of about 8 years.1,2 In 1892, Arnold Pick, a German physician, was the first to report a case of frontotemporal lobe dementia. Several years later, Alois Alzheimer described the pathological features: the cortex is spongy and neurons undergo ballooning. Specific spherical silver-loving inclusions called Pick vesicles, which are tau protein-positive intra-neuronal inclusions, appeared in the neurons. For quite some time thereafter, frontotemporal dementia has been referred to as Pick’s disease. Frontal and temporal pole atrophy is a typical morphological feature of frontotemporal dementia, but these changes are not very obvious in the early stage of the disease, and as the disease progresses, typical imaging manifestations of limited brain atrophy and hypometabolism are seen on MRI or SPECT. According to the 1998 Neary Diagnostic Criteria3 , frontotemporal degeneration mainly includes behavioral variant frontotemporal dementia (bvFTD), which is narrowly defined as frontotemporal dementia or frontotemporal dementia. Dementia or frontotemporal dementia, semantic dementia (SD) and progressive non-fluent aphasia (PNFA) are three clinical syndromes. Clinical features 1. Behavioral abnormalities in frontotemporal dementia (bvFTD) is characterized by personality and behavioral abnormalities with executive impairment, but speech impairment may also be present but is usually not a prominent manifestation and may be masked by more significant clinical symptoms such as personality changes. Personality changes and social deficits are the predominant clinical manifestations, appearing early in the course of the disease and continuing throughout the course of the disease. Perceptual abilities, spatial, use and memory functions are relatively preserved.4 A few patients with temporal lobe dementia with behavioral abnormalities may also exhibit peculiar hallucinations and Parkinson’s syndrome, the mechanism of which is unknown. A small number of patients who meet the diagnostic criteria for temporal lobe dementia with behavioral abnormalities but do not progress for a significant period of time are referred to as slowly progressive frontotemporal dementia. Patients with frontotemporal dementia perform better than Alzheimer’s disease on tests of visuospatial short-term memory, immediate, delayed, cued memory and recognition of words, implicit memory, and attentional persistence, in contrast to the Wisconsin Card Sorting Test (WCRT), the Stroop test, and the Connectedness Test B, which are performed worse than those with Alzheimer’s disease. The pattern of memory deficits in frontotemporal dementia is “frontal” amnesia. Although cognitive tests can distinguish most Alzheimer’s disease from frontotemporal dementia, a single neuropsychological test is not sufficient to diagnose frontotemporal dementia, and non-cognitive behaviors, such as lack of self-awareness, interpersonal dysphoria, antisocial behavior or apathy, and volitional deficits, are more sensitive than cognitive tests to distinguish Alzheimer’s disease from frontotemporal dementia.5 2. Semantic dementia Semantic memory impairment MRI shows severe atrophy of the inferior lateral temporal cortex and relatively normal structure of the medial temporal lobe, i.e., hippocampal system (including hippocampus, parahippocampal gyrus, and internal olfactory cortex); in Alzheimer’s disease, diffuse brain atrophy predominates, and there is no limited atrophy of the temporal cortex. Therefore, the degree of temporal pole and inferior lateral temporal lobe atrophy is the differential diagnostic imaging feature between semantic dementia and Alzheimer’s disease.6 Patients with semantic dementia mainly present with word finding difficulties, loss of general knowledge of objects, and comprehension impairment, and may also present with varying degrees of face recognition; behavioral abnormalities may also be present, but their characteristics are different from those of the behavioral abnormalities of temporal lobe dementia. Patients with semantic dementia mainly have temporal lobe atrophy, which can be further divided into left temporal lobe type and right temporal lobe type according to the severity of atrophy; behavioral abnormalities are mainly found in patients with right temporal lobe type semantic dementia. 3. Progressive nonfluent aphasia is a type of dementia based on language impairment, with disfluent verbal expressions, grammatical errors and telegraphic speech as the main manifestations. Progressive impairment of language is the only obvious area of impairment, at least in the first two years of onset. Standardized neuropsychological tests of language function help in the early identification of primary progressive aphasia (PPA). Behavioral and personality changes are extremely rare in progressive nonfluent aphasia and can distinguish between the behavioral abnormalities of temporal lobe dementia and semantic dementia. Progressive nonfluent aphasia progresses to advanced stages and often presents with extrapyramidal signs and symptoms, sometimes leading the clinician to change the diagnosis to corticobasal ganglia degeneration syndrome (CBS).7 In addition to temporal dementia with abnormal behavior, semantic dementia, and progressive nonfluent aphasia, there are a number of disorders that fall under the broad category of frontotemporal lobar degeneration.8 Kertesz and Munoz et al.8 noted that Progressive supranuclear palsy (PSP) and corticobasal ganglia degeneration syndrome, both Parkinson’s syndromes, are inextricably linked to frontotemporal lobe degeneration in terms of clinical presentation and pathological features. Both are neurodegenerative diseases with behavioral abnormalities and frontal lobe executive disorders; pathologically, both are tauopathies. In addition, patients with progressive nonfluent aphasia, although not showing motor symptoms in the early stages of the disease, can progress to progressive supranuclear palsy and corticobasal ganglia degeneration syndrome in many patients as the disease progresses. Recent studies have also found much overlap between frontotemporal lobar degeneration and amyotrophic lateral sclerosis (ALS), with multiple cases of amyotrophic lateral sclerosis or frontotemporal dementia-amyotrophic lateral sclerosis superimposed syndrome in autosomal dominant frontotemporal lobar degeneration families.8 Lomen-Hoerth et al. 9 found that frontotemporal dementia and amyotrophic lateral sclerosis were also frequently superimposed in sporadic cases. A study looking at 20 consecutive patients with frontotemporal dementia showed that although none of the patients had a family history of amyotrophic lateral sclerosis, three of them met the diagnostic criteria for amyotrophic lateral sclerosis and six met the diagnostic criteria for suspected amyotrophic lateral sclerosis by neuromuscular and electrophysiological examination10; and prospective studies have also shown that patients with amyotrophic lateral sclerosis are at increased risk of developing frontotemporal lobe degeneration increased risk of frontotemporal lobe degeneration. All of these findings suggest that frontotemporal lobar degeneration and amyotrophic lateral sclerosis may share a common neuroanatomical basis. It is now known that frontotemporal lobar degeneration is characterized by extrapyramidal syndromes (motor inability, tonicity, postural instability, etc., rarely tremor), which may suggest a tauopathy. Patients with progressive nonfluent aphasia with aphasia also suggest tauopathy, whereas most of the semantic dementias are TDP-43 proteinopathies. All patients with frontotemporal dementia-motor neuron disease superimposed syndrome have TDP-43 protein disease. The behavioral abnormalities of frontotemporal dementia are mostly TDP-43 protein disease, but a small percentage of them are Pick’s disease, which is a tau protein disease. Familial frontotemporal dementia should be screened for mutations in the MAPT and PRGN genes, but the clinical presentation of frontotemporal dementia caused by these two mutations is currently indistinguishable. Overall, there are no drugs approved for the treatment of patients with frontotemporal dementia. At this stage, the treatment of these patients is mainly symptomatic and does not modify the disease process or improve the prognosis. Moreover, due to the lack of conclusive evidence-based medical evidence, these drugs are empirical. Patients with frontotemporal dementia with abnormal behavior and personality changes are more prominent, and may present with impulsivity, disinhibition, abnormal sexual behavior, and stereotyped behavior, which are the reasons for patients and their families to visit the clinic. The 5-hydroxytryptamine (5-HT) reuptake inhibitors (SSRI) such as fluoxetine, fluvoxamine, sertraline, and paroxetine can be the drugs of choice for patients with behavioral abnormalities. This is mainly based on the results of several open studies with inconsistent findings from randomized controlled trials (RCTs). There are also randomized controlled clinical trials that have shown trazodone to be effective for abnormal behavioral symptoms, but its application is limited by the possibility of drowsiness. The results of a meta-analysis suggest that the application of 5-hydroxytryptamine reuptake inhibitors and trazodone is effective as the treatment of choice for patients with the behavioral abnormalities type of frontotemporal dementia.21 Non-classical antipsychotics may be tried for refractory behavioral abnormalities that are resistant to both of these drugs, and they are also effective for hyperemotional and excessive self-evaluation. However, adverse effects such as drowsiness, increased body mass, and pharmacogenic Parkinson’s syndrome should be noted during application. In particular, patients with frontotemporal dementia are particularly susceptible to extrapyramidal adverse effects of non-classical antipsychotics, and their clinical application requires caution. The cholinergic system is not involved in the pathogenesis of frontotemporal dementia, and therefore cholinesterase inhibitors are not recommended. However, the results of an open study suggest that cabalentine may partially improve behavioral symptoms in the behavioral abnormalities of frontotemporal dementia.22 Patients with frontotemporal dementia with behavioral abnormalities also often have pathological changes in eating habits and hyperphagia, and patients often have an increased body mass due to a sweet tooth, which can be treated with 5-hydroxytryptamine reuptake inhibitor drugs. In addition, patients with frontotemporal dementia with abnormal behavior may have apathy due to cingulate gyrus and middle frontal lobe involvement, which should be distinguished from depression. Treatment of apathy is difficult, and atypical antipsychotic medication may be tried if it occurs after an outbreak of disinhibitory symptoms. The cognitive impairment in patients with the behavioral abnormalities type of frontotemporal dementia is mainly executive impairment, decreased working memory, and the ability to shift timing, conceptualize, abstract, reason, organize, plan, and self-monitor is often involved, and there are no effective therapeutic drugs available. The treatment of patients with semantic dementia and progressive nonfluent aphasia is less well studied. It has been suggested that 5-hydroxytryptamine reuptake inhibitor therapy may be effective in patients with semantic dementia who have compulsive behaviors, for example.19 Since patients with semantic dementia and progressive nonfluent aphasia also do not have defects in the cholinergic system, cholinesterase inhibitors are theoretically ineffective in both. Treatment of frontotemporal lobe degeneration focuses on behavioral abnormalities that generally appear gradually and worsen at the beginning of the disease, reaching a peak in the middle stage of the disease, but in the late stage of the disease, due to frontal middle lobe involvement and impaired motivational capacity, patients show more apathy and withdrawal, and behavioral abnormalities are no longer evident. At this time, however, some patients have more significant symptoms of motor impairment, so non-classical antipsychotics should be discontinued. In addition, considering that patients with frontotemporal dementia are prone to extrapyramidal adverse countermeasures, attention should be paid to low dose use and early withdrawal of drugs in case of adverse reactions. Although there are case reports or series of case reports and small-sample open studies in recent years that have explored or verified the efficacy and safety of various drugs in the treatment of temporal lobe dementia, there is still a lack of large-sample, randomized, double-blind, controlled clinical trials, and the diagnostic criteria and efficacy evaluation methods currently used are not uniform, so in a strict sense, the treatment of temporal lobe dementia at this stage is still mainly empirical, and there is a lack of evidence-based There is a lack of evidence-based therapeutic drugs and methods. There is an urgent need to conduct rigorously designed randomized controlled double-blind clinical trials to evaluate existing treatments for frontotemporal dementia. Uniform diagnostic criteria for temporal lobe dementia should be adopted, and sensitive and applicable efficacy evaluation methods such as neuropsychiatric inventory (NPI), frontal lobe behavioral questionnaire, and executive ability questionnaire should be selected. In recent years, advances in pathology, molecular genetics and other related mechanisms have provided clues for the development of future therapeutic approaches.