January 2026 Research Update

This month added early, practical signals that symptom-focused approaches may help some people with hereditary spastic paraplegia, but the evidence is still preliminary. A small community program found that arm-crank exercise could be carried out safely and was acceptable to participants with limited leg mobility, including some people with HSP. Separate single-patient reports described improvements in walking or spasticity after specific medicines or an intensive home physiotherapy program, but case reports cannot show what will happen for most people. [1] [2] [3] [4]

In the exercise pilot, participants completed a group arm-crank program in community gyms, and no serious safety problems were reported. The study also reported improvements in upper-body function and quality of life measures, though results varied by site and there was no comparison group. For people with HSP who have trouble using their legs for aerobic exercise, this study supports the idea that a structured, accessible upper-body option can be tested and refined. [1]

In single-patient reports, fampridine (4-aminopyridine), a nerve-signal medication sometimes used for walking problems in other conditions, was linked with better walking and lower spasticity scores over about a year in one person with SPG4. Another person with SPG4 had a rapid and sustained reduction in leg spasticity after starting allopurinol (a medicine often used to lower uric acid), alongside reduced need for other anti-spastic medicines. These observations are important mainly as starting points for research, because improvements in one person can reflect placebo effects, day-to-day fluctuation, or other factors. [2] [3]

A separate case report in a 2-year-old child with SPG47 described improved motor abilities, trunk control, and spasticity after an 8-week, family-delivered, home developmental physiotherapy program. This fits with the general idea that intensive, structured therapy may support function in some children with complicated forms of HSP, but a single case cannot tell how large or reliable the benefit is across families. It also highlights that studies in children often focus on developmental skills rather than adult walking tests. [4]

For patients and caregivers, the main update is that researchers are testing realistic, everyday options to support function and well-being, but most of this month's evidence is early. The community arm-crank program is the strongest of these studies for day-to-day relevance because it directly tested feasibility and safety in a small group and reported participant experience, although it did not prove effectiveness. The medicine and physiotherapy reports describe what happened in individual people, which can help generate ideas for future trials, but they do not establish that the same approach will work for others or which HSP subtypes would benefit. [1] [2] [3] [4]

This month made the long-term picture of HSP a bit clearer by pairing a real-world progression study with studies looking beyond leg stiffness to the brain and thinking skills. In a large Austrian cohort, symptoms measured by a spasticity disability scale worsened slowly on average, with more rapid progression in complicated HSP than pure HSP. Cross-sectional studies suggested that some genetic types, especially SPG4 and SPG5, can have subtle changes in cognition or visual pathways that may not be the main complaint but can be detected with testing and imaging. [5] [6] [7]

In the Austrian follow-up cohort of 126 people with HSP, the average score change was about 0.9 points per year on the Spastic Paraplegia Rating Scale, and complicated HSP progressed faster than pure HSP. The study also described that many people were using rehabilitation and symptomatic treatments in routine care, and brain MRI changes were common in those who had imaging. This kind of natural-history information matters because it helps researchers choose realistic outcomes and timeframes for future clinical trials. [5]

In SPG4 and SPG3A, another study found that tests of the visual pathways and brain activity sometimes showed abnormalities even when these issues were not necessarily prominent in day-to-day symptoms. In SPG4, a substantial portion had visual evoked potential changes, EEG changes, and MRI changes, and people with certain types of SPAST genetic changes (microrearrangements) had more marked visual-test differences than those with other variant types. This adds to the idea that SPG4 can involve more than the legs for some people, although the study design cannot show how these findings relate to future disability. [6]

A separate study focusing on cognition reported that people with SPG5 had measurable difficulties in areas like visuospatial skills, executive function, and processing speed compared with controls, and it found that certain spinal cord measurements were strongly linked with memory and overall cognitive screening scores. The same study reported brain structure differences (like higher fluid space and lower brain tissue fraction) in those classified as having cognitive impairment. For patients, this supports that cognitive symptoms can be part of HSP for some subtypes, and it also points to spinal cord and brain measurements as possible research tools to track who is affected. [7]

For patients and caregivers, this month offers a more concrete sense of pace and variability, plus a reminder that HSP can include non-motor features in some people. The progression study may matter now for understanding what researchers mean by "slow progression" and why studies often need years of follow-up, especially because complicated HSP showed faster worsening than pure HSP. The cognition and visual-pathway studies mainly add understanding and potential research measures; they do not prove that everyone with HSP will have these issues, and they do not yet establish how test abnormalities should be used in routine care. [5] [6] [7]

This month strengthened the message that "HSP" can be the final label for many different causes, and careful diagnosis can change what families learn about prognosis and testing. One study tested a lab-based functional assay that can support or refute AP-4 related HSP when genetic variants are unclear. Several case-based reports described conditions that can look like HSP but have distinct genetic or metabolic signatures, including X-linked adrenoleukodystrophy and MTHFR deficiency. [8] [9] [10]

For AP-4 associated HSP, a small study in patient-derived skin cells measured an "ATG9A ratio" as a readout of AP-4 function and found evidence of AP-4 deficiency in 6 of 8 people evaluated for suspected AP-4 HSP. Two people did not show the abnormal pattern, suggesting the assay may help avoid mislabeling someone as AP-4 HSP when their variants are not actually causing AP-4 dysfunction. This is still specialized testing and needs broader validation, but it shows progress toward functional confirmation when DNA results are uncertain. [8]

A case report highlighted that a woman with progressive spastic paraparesis was diagnosed with X-linked adrenoleukodystrophy (X-ALD) based on characteristic blood markers and ABCD1 genetic testing. Another case report described adult-onset MTHFR deficiency presenting with spastic gait and very high homocysteine, along with multiple MTHFR variants, and summarized prior adult cases from the literature. Together, these reports emphasize that some HSP-like presentations have identifiable biochemical clues that point to a different underlying disorder. [9] [10]

Several additional reports broadened the list of rarer genetic causes linked to spastic paraplegia plus developmental or other neurologic features. ABHD16A-related disease was described in a new pediatric case and a review of prior cases, with a newly noted metabolic finding of elevated long-chain acylcarnitines in the new child. A child with IBA57-related mitochondrial disease (MMDS3) had spastic paraplegia along with seizures, vision loss, and white matter changes, and a SPG7 case series plus literature review reported that neurodevelopmental disorders were present in a minority of childhood-onset SPG7 cases. [11] [12] [13]

Other case reports focused on diagnostic boundaries and less typical symptoms within the spastic paraplegia spectrum. One person with SPG79A (UCHL1) was reported to have myokymia, a muscle twitching pattern seen on EMG, which had not been previously described for that subtype. Another report described a person whose juvenile-onset parkinsonism picture initially pointed to a different gene but later was reclassified as SPG15 after more comprehensive genetic testing, illustrating how complex symptoms can complicate early labeling. [14] [15]

For patients and caregivers, this month's diagnosis-focused studies mainly matter for understanding why genetic and metabolic testing can be detailed, and why re-checking uncertain genetic results sometimes happens. The AP-4 functional assay work may matter in the future by helping confirm whether a specific AP-4 gene change is truly causing disease, but it is not yet routine everywhere. The case reports about X-ALD and MTHFR deficiency matter as reminders that some people with an HSP-like pattern may have a different underlying condition with distinct lab markers, while the rarer genetic reports help families recognize that developmental delay, seizures, or vision issues can be part of certain spastic paraplegia subtypes or closely related genetic conditions rather than being unrelated. [8] [9] [10] [11] [12] [13] [14] [15]