Brits have been warned that early-onset Alzheimer's disease can present with signs that do not involve obvious memory problems. While the condition is commonly associated with forgetfulness, people who develop it before the age of 65 can initially experience very different symptoms.
Non-Memory Symptoms in Younger Patients
Professor Renaud La Joie, from the University of California, San Francisco (UCSF), explained that younger patients are more likely to experience symptoms that do not initially involve their memory. He said: "Patients with early-onset Alzheimer’s are more likely than older patients to present with symptoms unrelated to memory, at least initially. They might have difficulty interpreting what they are seeing despite a normal eye exam."
He added that patients might struggle with judging distances and may have trouble reading. Some may experience a decline in language abilities, having difficulty retrieving words and following long sentences, although speech remains fluent. Others may struggle with executive functioning, such as attention, problem-solving, planning, and adapting to changing situations.
Personality and Behaviour Changes
Changes in personality and behaviour can also occur. These can include becoming more irritable, losing confidence, feeling low, or losing interest in activities a person previously enjoyed. Other possible symptoms include becoming confused or disorientated, having difficulty with everyday tasks such as cooking or paying bills, and experiencing problems with movement, including unsteadiness, stiffness, or tremors.
The symptoms were highlighted as new research found important differences in the brains of younger and older Alzheimer's patients. Scientists studied 390 people with early-onset Alzheimer's, with an average age of 59, and compared them with 211 people with later-onset disease, whose average age was 78. All had mild cognitive impairment or mild dementia due to Alzheimer's.
Study Findings on Tau Accumulation
One in five of the younger patients had symptoms that were not related to memory. By comparison, memory was affected in 99% of the older group. Brain scans also found younger patients had greater deposits of tau, one of the proteins linked to Alzheimer's disease. Tau accumulated at more than twice the rate among the younger patients and was found to spread more widely through the brain.
Professor Gil Rabinovici, from UCSF, said: "We found that tau accumulation and spread was particularly aggressive in patients with early-onset disease and was more strongly related to progression in memory loss."
Researchers said it is still unclear why Alzheimer's develops much earlier in some people. Professor Konstantinos Chiotis, from the Karolinska Institutet in Stockholm, said: "We don’t fully understand why Alzheimer’s develops so early in some people. A small minority carry a known disease-causing mutation, but these were excluded from our study. A key question is whether other genetic factors explain this more aggressive tau pathology."
Researchers said the findings suggest treatments targeting tau could be particularly important for people with early-onset Alzheimer's.
