Frontotemporal dementia (FTD) is a neurodegenerative disorder that primarily affects the frontal and temporal lobes of the brain. It is the second most common cause of young-onset dementia, accounting for 10%–20% of dementia cases occurring before the age of 65.1 Current pharmacological options for FTD and its variants are limited. Selective serotonin reuptake inhibitors can help reduce behavioural symptoms such as apathy and compulsions but do not alter the progression of the disease.2 Given the lack of disease-modifying therapies, there is a growing interest in interventions that can modulate brain function and enhance neural plasticity. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that delivers a constant, low-intensity electrical current to specific brain regions through scalp electrodes, which alters cortical excitability, facilitating or inhibiting neuronal activity depending on electrode polarity.3 The effect of tDCS on two cases of FTD spectrum is described. Case 1: A 63-year-old, right-handed man presented with a two-year history of gradually worsening language difficulties, increasing apathy, and social withdrawal. Mini-mental State Examination (MMSE) score was 17 and included deficits in the language domain. Frontal Assessment Battery revealed deficits in conceptual abstraction, perseveration, and performance on Luria sequences. Language impairments were confirmed using the primary progressive aphasia/apraxia (PPA) of speech, and marked motivational decline was noted on the Apathy Evaluation Scale (AES). Magnetic resonance imaging (MRI) of the brain showed frontal and temporal lobe atrophy, aligning with the behavioural and linguistic profile typical of FTD–PPA Figure 1. Treatment with Sertraline 50 mg showed no improvement, so it was stopped. The patient underwent tDCS comprising 30 sessions (20 min each at 2 mA), administered five days per week with 2–3 sessions per day, and was planned for weekly tDCS on follow-up. The anodal electrode was positioned over the left inferior frontal gyrus (F7), with the cathodal electrode placed over the right homologous language region (F8). The intervention was well tolerated. Over the course of treatment, caregivers observed notable improvements in social engagement and spontaneous communication Table 1Figure 1: Magnetic resonance imaging findings of frontotemporal atrophy of case 1Table 1: Changes in cognitive and behavioural scores during transcranial direct current stimulation interventionCase 2: A 61-year-old, right-handed, unemployed for the past three years, presented with a gradual decline in executive abilities, expressive speech, and apathy over two years, accompanied by memory impairment. Over the past 18 months, he developed gait instability with backward falls, axial rigidity, and difficulty looking downwards. Neurological examination revealed vertical supranuclear gaze palsy, bradykinesia, and postural instability. Cognitive evaluation demonstrated frontal-executive dysfunction with mild global decline on MMSE and marked apathy on the AES. MRI brain showed cortical and subcortical atrophy Figure 2. A diagnosis of FTD–progressive supranuclear palsy (FTD–PSP) complex was made in liaison with the neurologist. Levodopa was not well tolerated and therefore discontinued. At the time of the tDCS intervention, he was only taking Melatonin 5 mg along with oral hypoglycaemic agents (Metformin and Glimepiride). The treatment was well tolerated. Caregivers reported improved apathy and some improvement in executive function; however, the motor symptoms persisted Table 1.Figure 2: Magnetic resonance imaging findings of frontotemporal atrophy of case 2The potential efficacy of tDCS as a neuromodulatory treatment in two cases of FTD is examined. Case 1 exhibits significant language impairments and apathy with notable frontotemporal atrophy, indicative of PPA-type FTD. Case 2 presents language and executive dysfunctions alongside severe motor symptoms (gaze palsy, falls, rigidity), suggesting a PPA-PSP variant. tDCS exerts its effects primarily through modulation of cortical excitability. Anodal stimulation depolarizes neuronal membranes, increasing the likelihood of action potential firing, whereas cathodal stimulation can reduce hyperactive or maladaptive contralateral activity, effectively rebalancing interhemispheric inhibition and excitation.4 In these cases, placing the anode over the left inferior frontal gyrus specifically targeted hypoactive nodes within the language and executive control network, while the cathode over the right homologous language region led to inhibition of the inhibitory effect of the right hemisphere over the left hemisphere, leading to disinhibition of the left language area.5 This electrode configuration is informed by functional and structural connectivity studies, which suggest that focal modulation of the left inferior frontal region can influence downstream areas involved in lexical retrieval, semantic integration, and verbal working memory.5 From a network perspective, tDCS may facilitate long-term potentiation-like plasticity and strengthen residual synaptic connections in the degenerated frontotemporal pathways. It may also enhance functional connectivity between the left inferior frontal gyrus and contralateral homologues, compensating for lost lateralized processing.6 Additionally, modulation of frontostriatal circuits could underlie the observed improvements in executive function and motivational drive by indirectly enhancing dopaminergic signalling in prefrontal and striatal regions.6 The modest gains in language performance, despite targeted stimulation, underscore the challenge of restoring function in neurodegenerative networks with progressive synaptic and neuronal loss.7 Nevertheless, even small improvements in naming, word retrieval, or spontaneous speech can have a meaningful functional impact, particularly when combined with pharmacological or behavioural interventions. The cases suggest that tDCS may exert a differential effect across cognitive domains, favouring modulation of network efficiency, attentional control, and motivation, rather than directly reversing linguistic deficits. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Authors’ contributions Conceptualization, patient recruitment, clinical assessment, manuscript drafting: SSS; Data collection: NS; Manuscript editing, critical revision: AJV, MKS, BS, SKS. The final manuscript has been read and approved by all the authors Data availability statement The data supporting the findings of this study are available from the corresponding author upon reasonable request. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Sinha et al. (Fri,) studied this question.