Development of frontotemporal dementia in a patient followed up with late-onset bipolar disorder: A case report

Frontotemporal dementia is an insidious neurodegenerative clinical syndrome characterized by progressive deficits in behavior, executive function, and language. The initial clinical presentation of some patients with FTD may resemble bipolar mood disorder.In this case, it was planned to diagnose FTD in addition to the emergence of behavioral and cognitive problems in the patient followed up with bipolar mood disorder and to discuss the difficulties experienced in the treatment. In 2017, he was diagnosed with bipolar mood disorder due to loud speech, irritability, thinking that he was cast under a spell, increased spending, driving fast, swearing at relatives. He was followed up with lithium, olanzapine and quetiapine treatment, and he benefited from the treatment. The diagnosis of frontotemporal dementia was considered in the patient who underwent brain diffusion MRI and PET CT in December 2020, upon the onset of the complaint of forgetfulness. Informed consent was obtained from the patient and his relatives.In conclusion, in our case who was followed up with bipolar disorder, a co-diagnosis of frontotemporal dementia was made with the emergence of memory and behavioral pathologies in the later follow-ups. With the diagnosis of FTD, the severity of the patient's manic episodes, clinical presentation, and treatment response changed. Therefore, FTD should be considered in the differential diagnosis of patients who are followed up with bipolar disorder and subsequently have clinical changes.