Although often thought of as a disease of older people, around 5% to 7% of people with Alzheimer’s disease are under age 65. This is called young onset or early onset Alzheimer’s disease. It usually affects people in their 40s, 50s and early 60s. Alzheimer’s disease diagnosed later in life and young onset Alzheimer’s disease have the same causes, involving accumulation of abnormal proteins in the brain. Amyloid which forms plaques, and tau which forms tangles within brain cells are the proteins that together damage brain cells and cause the disease.
While tangles and plaques develop in the brain as we age, in people living with Alzheimer’s disease, these abnormal proteins occur significantly more and cause damage beginning in the parts of the brain that control memory. The symptoms in young onset Alzheimer’s disease are similar to those in Alzheimer’s disease diagnosed in later life. These include impairments in short-term memory which cause difficulty remembering recent events, for example appointments, or difficulty finding your way around familiar places or finding things, for example, car keys. As the disease progresses, long-term memory also becomes affected which impacts ability to recognize people, including family members. Language and other cognitive abilities also become affected and the person with Alzheimer’s disease will need more support to manage day-to-day functions, including self-care.
Although the commonest symptom in young onset Alzheimer’s disease is memory impairment, around 32% of people can have other symptoms. Some individuals may have visual or spatial problems (for example, difficulties with seeing what and where things are when driving or reading), also known as posterior cortical atrophy. Others may have language difficulty, such as with word finding or fluency. This is called logopenic aphasia, a type of primary progressive aphasia. Other individuals may experience changes in their behaviour or personality, for example becoming apathetic, passive, or disinhibited. In some people too, Alzheimer’s disease might be inherited, due to certain rare genes that run within families, affecting several generations. This type of Alzheimer’s disease is called familial Alzheimer’s disease.
Regardless of the symptoms, young onset Alzheimer’s disease is not as rare as people think, although it is poorly recognized. This is in part because of the young age when symptoms are first noticed or diagnosed and the general misconception that dementia affects only older adults. Symptoms can also present differently in individuals and may involve changes to memory as well as other changes in vision or language. As a result, individuals experiencing symptoms of young onset Alzheimer’s disease are more likely to experience delays getting a diagnosis or be misdiagnosed. Because some of these changes can affect a person’s mood and personality, some individuals with young onset Alzheimer’s disease are told they have mental health problems such as depression or are undergoing stress. Individuals with young onset Alzheimer’s disease also face stigma and stereotypes about the disease, for example that they are too young to have dementia or because their memory is still intact their diagnosis is questioned.
Despite delays in getting a diagnosis, it is a first important step to receiving necessary support and care. For individuals with young onset Alzheimer’s disease, this is typically done by a neurologist or psychiatrist. Getting a diagnosis involves several assessments to rule out other medical conditions, which can sometimes be distressing or intrusive and time-consuming. However, this testing is needed to arrive at an accurate diagnosis.