FDG-PET scan does not support clinical FTD diagnosis

GG06

Hi,

Before I get into the reason for my post (my first), I want to express how much this forum has helped me over the last 5 months. I have learned so much from all of you.

Without getting into too much background (because it would be 10+ pages), my 64-year-old husband was diagnosed, separately, by a neuropsychologist and an NP-Memory Center in May 2023 with FTD-behavioral and semantic variants. His CT scan (Feb 2023) was unremarkable. His MRI (Mar 2023) showed slight atrophy in the anterior right temporal lobe. He has had bloodwork to rule out other causes.

This past Friday he had an FDG-PET scan that showed the following:

FINDINGS: Mild hypometabolism is noted in the right greater than left parietal lobes. Moderate decreased activity is noted in the right temporal lobe and mild decreased is noted in the left temporal lobe. However, there is normal activity in the precuneus which indicates that a neurodegenerative dementia is unlikely. Preserved activity is noted in the cingulate gyrus, bilateral frontal lobes, and occipital lobe. Activity in the subcortical gray matter is preserved. Overall, the findings suggests a non-neurodegenerative dementia. Normal uptake in the bilateral frontal lobes indicates that frontotemporal dementia is unlikely.

The geriatric doctor at the memory center called to tell me she sent a message to the neurologist in charge at the memory practice for clarification on the findings. I am in a state of disbelief. I have scoured the internet to find a non-neurodegenerative cause of my husband's dementia, but nothing seems to match his symptoms. He continues to decline - cognitively and behaviorally.

Has anyone else had this issue? It's not that I'm upset he doesn't have FTD or other neurodegenerative disease, I just want to know what is causing his dementia. We've been trying to get a diagnosis (correct) for 6 months now.

SDianeL

This must be so scary and frustrating!! I also don't have a diagnosis for my DH because they can't do an MRI and they don't want to pay for a PET Scan. I Found this: Nondegenerative Dementias and Encephalopathies Nondegenerative dementias are a diverse but important group of cognitive disorders because they may be reversible with treatment. Thus, it is important to evaluate for such when suspected. Many of the causes of nondegenerative dementia result in what is known as a subcortical dementia. Subcortical dementia is thought to be primarily due to damage to the frontal subcortical connections, and typical clinical features include inattention, bradyphrenia (slowed thought process), executive dysfunction (difficulties planning and sequencing tasks), apathy, psychomotor slowing, and mood disorders. Gait apraxia and urinary difficulties may coexist. Cortical features such as agnosia, seizures, aphasia, and ideomotor apraxia are typically absent. Also this: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3039161/

GG06

@SDianeL Thank you for the information. I've actually already read the article. They have ruled out encephalopathies, and the other dementias referenced don't seem to match his symptoms. But, I have no idea. I'm just so frustrated. Hoping the doctor will call me tomorrow. Thanks again for responding.

M1

Hi GG06. The sad truth: imaging doesn't do much in these diagnoses, including PET scans. The changes in the brain are way too much at the microscopic level for scans to help, for the most part. If the clinical diagnosis is still FTD, that's what you've got. Autopsy is the only way to make definitive tissue diagnoses. I hope the doc will have something helpful to say tomorrow.

GG06

@M1 your comment really helped calm me down and relax a bit. Thanks so much for giving your insight.

Iris L.

The two main things to understand about an FTD diagnosis 1) the course of the disease is distinct from the course of Alzheimer's Disease and 2) medications used for Alzheimer's Disease may make patients with FTD worse. There is a book, "What If It's Not Alzheimer's?"

Iris

GG06

Thanks Iris. I really appreciate your response. I’ve read the book and about the differences of the two diseases. It does seem like the PET scan shows more of an AD path, but the radiologist’s wording of “non-degenerative dementia” is what’s throwing me. My husband isn’t on any medication that other than sertraline and a cholesterol med. He also has a strong paternal family history of dementia. His father, two aunts, and uncle had late onset. A cousin died of Alzheimer’s at 62.

Iris L.

What M1 said about imaging is correct, these studies must be viewed in conjunction with the history and clinical presentation. Given the description of nondegenerative dementia, I would look in the direction of a pseudodementia due to depression. Is the sertraline newly prescribed? If there is a question of depression, it should be aggressively treated pharmacologically and with talk therapy for at least 6-8 weeks to see if there is improvement. Antidepressants can be prescribed singly or in combination. Find a psychiatrist who understands pseudodementia. Depression can present as dementia.

The other point to keep in mind is that the degenerative dementias are progressive. It is expected that there will be decline over time. As other diseases are being ruled out, his course and prognosis should become clearer over the next few months. Diagnosing the dementias is not straight-forward.

Iris

GG06

@Iris L. He's been on sertraline for just under 2 years. He worked with a therapist and psychiatrist for about a year. He always struggled with anxiety and was in a high-stress job. The sertraline has helped tremendously, but since January, when his symptoms progressed and he lost self-awareness, he has been happy and anxiety-free. He no longer has a diagnosis of depression.

Just a brief history... in 2019 he told his doctor he was having trouble remembering people and getting his words out. In 2020 we started noticing behavior and personality changes. In 2021 language/speech, inappropriate social behaviors, and deterioration in hygiene became problematic. These issues have become more pronounced and frequent. He has prosagnosia and anasognosia. His behavior seems on the level of a 6-8 year old (I'm a former early childhood teacher).

GG06

@SDianeL I am so sorry you are struggling to get a diagnosis for your DH. It must be maddening not to be able to get diagnostic testing. I wish I had answers to help.

Marta

GG06 - since you are relatively new, I’d like to make you aware that M1 and Iris are both physicians- so now you have had two consultations. Diane is living your dilemma. You are in a good place here.

Iris L.

Given the additional history, I lean more toward dementia versus pseudodementia. I am not making a diagnosis, because that is not my place and this board is not for that. It is for making suggestions. You have covered just about everything I can think of. Bring all of this history to your consultant. Present all of it in the beginning, do not leave significant history out, such as his depression history.

Since his functioning is at a low level already, it is not likely to revert to normal. Be aware that you may not get a specific, definite diagnosis. This happens sometimes. You may get a "presumptive" diagnosis. You will have to come to terms in order to move forward. Keep posting. You can also seek support from the other spouses on the Spouse/Partner board.

Iris

harshedbuzz

I'm not a doctor, but I wonder if this is a situation where your DH has (or is heading into) a mixed dementia diagnosis. This can make pinning down the type of dementia difficult even with advanced testing like a PET scan. We went through a convoluted path to diagnosis with my dad.

My dad was eventually diagnosed with both Alzheimer's and an alcohol-related dementia called Wernicke-Korsakoff's. I had noticed specific behaviors/symptoms of both over the years but didn't fully appreciate what I was seeing at the time. When he was initially diagnosed, the chief resident in the ER thought WKS. Dad was admitted and started IV Thiamine to treat. The attending/professor of Medicine took over the next day; he felt dad had garden variety Alzheimer's and seemed annoyed that he was hospitalized. In retrospect I realize the history given in the ER by my mom (who'd been in denial and fighting me on getting an evaluation) painted the picture of a much more acute onset of psychosis while the conversation I had with neurologist described a more subtle onset with issues starting a full decade prior to his admission.

Dad was discharged to a SNF for physical rehab. During that time the IV Thiamine and abstinent lifestyle prescribed for WKS did clear a lot of the worst of dad's confusion and delusions and he was functioning world's better so it really looked like the resident was correct in his call. Dad wasn't 100% but the improvement was dramatic. At the series of follow-up appointments at the hospital's memory center the new doctor did more testing including a PET scan and neuropsych testing which led to the mixed-dementia diagnosis-- he had both Alzheimers and WKS. I feel like at the time of his diagnosis, the Alzheimer's was fairly mild-- maybe a stage 3-4 with the WKS being more prominent, but over time the Alzheimer's worsened and became the bigger concern.

HB

GG06

@harshedbuzz Thanks for your comments. I've wondered about mixed dementia as well. It's all so frustrating.

@Iris L. Thank you again for your insight.

I just spoke with the neurologist and NP. They both strongly feel my husband has FTD and this scan falls into the 16% of false negative PET scans. It sounds strange, but I am relieved. My stepson and daughter-in-law (who is a pediatric NP) want my husband to repeat the scan. I'm not on-board with that. I told them I don't think insurance will pay for it, nor will my husband go for it, and given all the previous testing, and 3 medical professionals' opinions of an FTD diagnosis, I think this what he has.

I am so appreciative of everyone who chimed in and supported me as I waited for the doctor's update. And just an FYI, I've followed you all since Feb 16, 2023!

MN Chickadee

I wouldn't bother with more testing but I bet if he went through another scan in a year or two it would say something different. My mother had a normal MRI despite some pretty severe signs of dementia. She went through the full neuro-psych testing that took hours and saw the neurologist and they repeatedly told her she was fine. She knew, and we all knew, she was not fine. We finally got the Alz diagnosis a nearly decade later when she had declined to the point of having the skills of a two year old. For some people the diagnosis process follows a predictable trajectory and for others it never happens and you just run with informed assumptions. There is no cure for any of the dementias he could have since it sounds like you have ruled out the causes that could be treated (vitamin deficiencies, tumors etc) or mimics of dementia. To me this means not a whole lot would be gained from further testing since none of this is reversable. But it's good you know to suspect FTD because it could affect what medications he should take. Better than finding out the hard way of guess and check on meds.

Marta

https://alzconnected.org/discussion/comment/177977#Comment_177977

And now you are one of us.

GG06

@Marta Thanks so much. I am so grateful for this forum.

@MN Chickadee Thank you for sharing some of your experience. I learn so much from reading everyone's stories.

SDianeL

@GG06 - your description of your DH's progression is almost exactly like my DH. My husband is 78 yrs old. 2 years ago he started forgetting how to misspell common words, had trouble with familial relationships (he asked my daughter what was her brother to her) he couldn't use our new iPhone and he would interrupt people because he said if he didn't, he would forget what he wanted to say. People thought he was just being rude. During COVID we were isolated together and I noticed more things. He's always been mechanically minded & his jobs were in those fields. He could no longer do simple mechanical tasks. His behavior changed and he would get angry when he couldn't do something or if he misplaced something which was happening all the time. He stopped showering & his behavior worsened and he became angry with me. He began to have language issues and would ask me to tell someone else what he was thinking, and when I didn't know, he would get angry with me. It took over 6 months to get him evaluated. Now he's having hallucinations at night & can't tell dreams from reality. He asks me the same question over & over & over. He can't operate the cable remote. He's obsessed with things & I can't deter him. He is no longer rational, logical or emotional. I spoke to the Neurologist today about a PET Scan since he can't have an MRI. She said PET Scans don't show what they need to see like MRI's do. So since another scan won't change the outcome or the treatment (of which there is none) I can't see putting him through another scan. He started Memantine 6 months ago and started Risperidone low dose last night. He did sleep better and is calmer today so hope it helps him. Please keep us posted. This forum has helped me so much.