Britons have been warned that early-onset Alzheimer’s disease can begin with symptoms that are not linked to obvious memory loss. Although Alzheimer’s is widely associated with forgetfulness, people who develop the condition before the age of 65 may initially experience a different set of warning signs.
Alzheimer’s diagnosed before 65 is known as young-onset or early-onset Alzheimer’s disease. Professor Renaud La Joie, of the University of California, San Francisco (UCSF), said younger patients are more likely to develop symptoms that do not initially affect 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 having a normal eye examination.
“They may struggle to judge distances or have difficulty reading. Some experience a decline in language skills, including trouble finding words or following long sentences, even though their speech remains fluent.
“Others may experience problems with executive functioning, including attention, problem-solving, planning and adapting to changing circumstances.”
Personality and behavioural changes may also develop. These can include increased irritability, a loss of confidence, low mood or reduced interest in activities the person previously enjoyed.
Other potential warning signs include confusion or disorientation, difficulty managing everyday activities such as cooking or paying bills, and movement problems including unsteadiness, stiffness or tremors.
The symptoms have been highlighted after new research identified important differences between the brains of younger and older people with Alzheimer’s disease.
Scientists studied 390 people with early-onset Alzheimer’s, whose average age was 59, and compared them with 211 patients who developed the disease later in life, with an average age of 78.
All the participants had mild cognitive impairment or mild dementia caused by Alzheimer’s disease.
One in five of the younger patients experienced symptoms unrelated to memory. In contrast, memory was affected in 99% of those in the older group.
Brain scans also showed that younger patients had higher levels of tau deposits, one of the proteins associated with Alzheimer’s disease.
Tau built up at more than twice the rate seen in younger patients and spread more extensively throughout the brain.
Professor Gil Rabinovici, also from UCSF, said: “We found that tau accumulation and spread were particularly aggressive in patients with early-onset disease and were more strongly associated with the progression of memory loss.”
Researchers said it remains unclear why Alzheimer’s develops considerably earlier in some people than in others.
Professor Konstantinos Chiotis, from the Karolinska Institutet in Stockholm, said: “We do not fully understand why Alzheimer’s develops so early in some people.
“A small minority carry a known disease-causing mutation, but these individuals were excluded from our study.
“A key question is whether other genetic factors help explain this more aggressive tau pathology.”
The researchers said the findings suggest that treatments targeting tau may be especially important for people with early-onset Alzheimer’s disease.
