Loss of Y chromosome linked to Alzheimer’s disease

ADHD may appear for first time in adulthood

MIAMI, May 24, (Agencies): About one in five men over age 80 lose the Y chromosome from their blood cells, and this condition has now been linked to an increased risk of Alzheimer’s disease, researchers said Monday.

The condition known a loss of Y, or LOY, is the most common genetic mutation acquired during a man’s lifetime.

Previous research has shown LOY can raise the likelihood of cancer and is more frequently found in smokers.

Now, researchers say the condition may serve as a predictive biomarker for a wider range of health problems.

For the study in the American Journal of Human Genetics — led by Lars Forsberg and Jan Dumanski of Uppsala University in Sweden, along with colleagues Britain, France, the United States and Canada — researchers examined cases of LOY in more than 3,200 men with an average age of 73.

Around 17 percent showed LOY in blood cells.

Those who had been already diagnosed with Alzheimer’s had a higher degree of LOY, they found.

Also, those who had not yet been diagnosed with dementia but had LOY were more likely to develop Alzheimer’s in subsequent years.

Predictive

“Having loss of Y is not 100 percent predictive that you will have either cancer or Alzheimer’s,” cautioned Forsberg.

Some men with LOY in the study lived with no symptoms well into their 90s.

“But in the future, loss of Y in blood cells can become a new biomarker for disease risk and perhaps evaluation can make a difference in detecting and treating problems early.”

According to Chris Lau, professor in the department of medicine at the University of California, San Francisco, the study sheds little light on why Alzheimer’s risk may be elevated in these men.

“Although informative, the study is preliminary in nature and only highlights the fact that the Y chromosome could serve important functions beyond male sex determination and sperm production,” said Lau, who was not involved in the study.

“What exactly on the Y chromosome that increases the risk of Alzheimer’s disease is the key issue.”

Since the Y chromosome contains many genes — some unique to men and others shared with women, who do not have a Y chromosome — more research is needed.

“It depends on what is lost to determine what is important for Alzheimer’s disease. Without such information, the loss of Y is just an observation,” Lau said.

ADHD:

Attention Deficit Hyperactivity Disorder (ADHD), usually diagnosed in children, may show up for the first time in adulthood, two recent studies suggest.

And not only can ADHD appear for the first time after childhood, but the symptoms for adult-onset ADHD may be different from symptoms experienced by kids, the researchers found.

“Although the nature of symptoms differs somewhat between children and adults, all age groups show impairments in multiple domains — school, family and friendships for kids and school, occupation, marriage and driving for adults,” said Stephen Faraone, a psychiatry researcher at SUNY Upstate Medical University in Syracuse, New York and author

of an editorial accompanying the two studies in JAMA Psychiatry.

Faraone cautions, however, that some newly diagnosed adults might have had undetected ADHD as children. Support from parents and teachers or high intelligence, for example, might prevent ADHD symptoms from emerging earlier in life.

It’s not clear whether study participants

“were completely free of psychopathology prior to adulthood,” Faraone said in an email.

One of the studies, from Brazil, tracked more than 5,200 people born in 1993 until they were 18 or 19 years old.

At age 11,393 kids, or 8.9 percent, had childhood ADHD. By the end of the study, 492 participants, or 12.2 percent,

met all the criteria for young adult ADHD except the age of diagnosis. Symptoms Childhood ADHD was more prevalent among males, while adult ADHD was more prevalent among females, the study also found.

Just 60 of the nearly 400 kids with ADHD still had symptoms at the end of the study, and only 60 of the nearly 500 adults with ADHD had been diagnosed as children.

“The main take-home message is that adult patients experiencing significant and lasting symptoms of inattention, hyperactivity or impulsivity that cause impairment should seek evaluation, even if they began recently by their perception or if family members deny their existence in childhood,” senior study author Dr Luis Augusto Rohde, a psychiatry researcher at Federal University of Rio Grande Do Sul in Brazil said by email.

The second study focused on 2,040 twins born in England and Wales in 1994 and 1995. During childhood, 247 of them met the diagnosis criteria for ADHD. Of those, 54 still met the diagnosis criteria for the disease at age 18.

Among 166 individuals with adult ADHD, roughly one third didn’t meet the criteria for ADHD at any of four evaluations during childhood, the study also found.

It’s possible some of these adults had undiagnosed ADHD as kids, but symptoms may also look different in older people than they do in children, said senior study author Louise Arseneault of King’s College in London.

People with adult ADHD may have more inattentive symptoms like being forgetful or having difficulty concentrating, whereas children with ADHD may have more hyperactive symptoms, Arseneault said by email. “And if adults do experience hyperactive symptoms, these symptoms may manifest more as feelings of internal restlessness rather than obvious hyperactive behavior like running or climbing around in inappropriate situations,” she said.