Patients May Show Signs of Disease Years Before Their Diagnosis

Grip strength becomes weaker before obvious symptoms appear, study says

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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People who go on to develop a neurodegenerative disease such as Parkinson’s may experience poorer overall health and show signs of disease many years before they get diagnosed, according to a study from the University of Cambridge in the U.K.

For those with Parkinson’s, grip strength in both hands become weaker over the years prior to diagnosis, researchers say. This means that they may have a harder time doing certain tasks years before their first symptoms appear.

The findings may open the way for doctors to screen people in the future and select those who could benefit from early interventions.

“This is a step towards us being able to screen people who are at greatest risk — for example, people over 50 or those who have high blood pressure or do not do enough exercise — and intervene at an earlier stage to help them reduce their risk,” Nol Swaddiwudhipong, MD, the study’s first author, said in a university press release.

The study, “Pre-diagnostic cognitive and functional impairment in multiple sporadic neurodegenerative diseases,” was published in the journal Alzheimer’s & Dementia.

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Few treatments are effective for neurodegenerative diseases such as Parkinson’s. This is partly because these diseases are often only diagnosed after symptoms appear, perhaps years after the underlying neurodegeneration has begun. By the time patients take part in clinical trials, for example, it may be too late to alter the course of their disease.

“The problem with clinical trials is that by necessity they often recruit patients with a diagnosis, but we know that by this point they are already some way down the road and their condition cannot be stopped,” said Tim Rittman, PhD, from the department of clinical neurosciences at Cambridge, and the study’s senior author.

Researchers are now turning more attention to earlier stages of disease. “If we can find these individuals early enough, we’ll have a better chance of seeing if the drugs are effective,” Rittman added.

However, diagnosing people at the earliest stages of disease, before the onset of symptoms, is difficult.

To investigate whether it was possible to detect changes in brain function before symptom onset, Swaddiwudhipong and colleagues at the University of Cambridge drew on data from the U.K. Biobank, a database with health information from more than half a million adults recruited between 2006 and 2010 from the general U.K. population.

More than 5,600 went on to develop Parkinson’s, Alzheimer’s disease, frontotemporal dementia, progressive supranuclear palsy, dementia with Lewy bodies, or multiple system atrophy.

Those who developed Parkinson’s (2,370 people) were diagnosed a mean of 7.4 years after baseline (the start of the study). Their mean age was 62.8 years and 60.3% were men.

The researchers analyzed patient data on overall health, weight changes, and number of falls, as well as the results of tests measuring grip strength, memory, problem-solving abilities, and reaction times at baseline and over the years prior to diagnosis.

To serve as controls were 493,735 individuals who were not diagnosed with a neurodegenerative disease within the study’s timeframe.

Compared to control individuals, people who went on to develop a neurodegenerative disease experienced poorer overall health at baseline.

They “have preserved pre-symptomatic cognition and good evidence of preserved outcomes on some measures,” the researchers wrote. However, in the years prior to their diagnosis, those who went on to develop Parkinson’s saw their grip strength become gradually weaker in both hands.

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People who went on to develop another neurodegenerative disease, such as Alzheimer’s or frontotemporal dementia, scored worse than control individuals when it came to problem-solving tasks, reaction times, remembering lists of numbers, remembering something later on, and pair matching.

“A screening panel based on cognition and function could be followed by disease-specific biomarkers to further improve risk stratification,” the researchers wrote.

“When we looked back at patients’ histories, it became clear that they were showing some cognitive impairment several years before their symptoms became obvious enough to prompt a diagnosis,” Swaddiwudhipong said. “The impairments were often subtle, but across a number of aspects of cognition.”

However, Rittman said, “people should not be unduly worried if, for example, they are not good at recalling numbers. Even some healthy individuals will naturally score better or worse than their peers.”

Nonetheless, “we would encourage anyone who has any concerns or notices that their memory or recall is getting worse to speak to their [general practitioner],” he added.