A recently recognized form of dementia may be characterized by unusual changes in sound preferences, according to novel research.
Dementia is a broad term for cognitive decline severe enough to interfere with daily life. While Alzheimer’s disease is the most common form, characterized by memory loss and other cognitive changes, We find many types of dementia.
There are three main variants of frontotemporal dementia: a behavioral variant affecting personality and behavior, a non-fluent variant impacting speech production, and a semantic variant affecting knowledge and speech comprehension.
Although, some researchers believe there may be a fourth variant of frontotemporal dementia. Evidence for this fourth variant was detailed in a recent case study.
A 68-year-old man, identified as CP, developed an unusual fondness for the sound of Spitfire airplane engines. His wife first noticed the peculiar behavior approximately two years before his dementia diagnosis.
CP lived near an airfield where older planes frequently flew overhead. He would stop whatever he was doing and rush outside, greeting the aircraft and becoming visibly emotional each time he heard them. This was a new behavior for him.
His affection for the engine sounds was specific to this type of aircraft; he didn’t react similarly to other planes and showed no general interest in aviation.
Conversely, the sound of birdsong and high-pitched human voices irritated him. He too became exceptionally particular about his music choices.
Several years before his newfound love for Spitfire engines, CP had become irritable and bad-tempered. He grew increasingly distant and apathetic towards others, and lost control over his impulses and awareness of socially acceptable behavior.
He also lost his sense of humor, developed a craving for sweets, and became fixated on chess and word searches. At times, he failed to recognize familiar faces, but had no trouble recognizing people’s voices on the phone.
Research Findings
Approximately five years after the onset of his symptoms, CP was diagnosed with behavioral variant frontotemporal dementia. However, researchers suggest he may have had a newer, fourth variant – sometimes called “right temporal variant.”
This variant is named for the significant tissue loss that occurs in the right temporal lobe of the brain. This brain region is primarily involved in understanding concepts and deriving meaning from nonverbal information, such as social cues. Brain scans of CP revealed substantial loss of tissue in this area.
The right temporal variant of frontotemporal dementia appears to cause a combination of symptoms typical of both the behavioral and semantic variants. However, there is ongoing debate within the research community regarding how to best define this subtype.
