In some cases, inherited genetic mutations cause temporal wasting, also known as frontotemporal lobar degeneration, but in most cases, the cause is unknown. Further research must be conducted to discover the true cause, according to the National Institute on Aging.
Scientists from the National Institute on Aging describe patterns of change in the brain seen in an autopsy after death, including loss of neurons and abnormal amounts or forms of proteins called tau and TDP-43. These proteins occur naturally in the body and help cells function properly. When the proteins do not work properly, for reasons not yet fully understood, damage occurs to neurons in specific brain regions.
Frontotemporal lobar disorders are grouped into three types that are defined by early symptoms. Behavioral variant frontotemporal dementia causes changes in personality, behavior, emotions and judgment. Primary progressive aphasia is characterized by changes in language ability, including speaking, understanding, reading and writing. Corticobasal syndrome, also known as supranuclear palsy or amyotrophic lateral sclerosis, is characterized by various difficulties with physical movement, including the use of one or more limbs, difficulty walking, frequent falls and poor coordination. Symptoms vary from one person to another and some symptoms are common to more than one disorder, making it difficult to identify which type of frontotemporal lobar disorder is present in the early stages of the disease.