Progressive supranuclear palsy (PSP), also known as [Steele-Richardson-Olszewski syndrome](/diseases/steele-richardson-olszewski-syndrome), is a [4R-tauopathy](/mechanisms/4r-tau-cbs) that exhibits notable differences between male and female patients. Understanding these gender-specific variations is increasingly recognized as important for clinical trial design, treatment decisions, and patient counseling[1]. Gender differences in neurodegenerative diseases extend beyond mere epidemiological observations and may inform our understanding of disease mechanisms, therapeutic responses, and personalized medicine approaches.[@gozes2023]
Epidemiological studies consistently show a male predominance in PSP prevalence.[@mahale2022] A large retrospective analysis of 334 clinically diagnosed PSP patients conducted over 21 years demonstrated a male-to-female ratio of approximately 1.6:1, with 209 male patients (62.2%) and 125 female patients (37.4%)[2]. This male predominance has been reported across multiple cohort studies globally, suggesting a biological basis for the gender disparity rather than simply diagnostic bias.
Progressive supranuclear palsy (PSP), also known as [Steele-Richardson-Olszewski syndrome](/diseases/steele-richardson-olszewski-syndrome), is a [4R-tauopathy](/mechanisms/4r-tau-cbs) that exhibits notable differences between male and female patients. Understanding these gender-specific variations is increasingly recognized as important for clinical trial design, treatment decisions, and patient counseling[1]. Gender differences in neurodegenerative diseases extend beyond mere epidemiological observations and may inform our understanding of disease mechanisms, therapeutic responses, and personalized medicine approaches.[@gozes2023]
Epidemiological studies consistently show a male predominance in PSP prevalence.[@mahale2022] A large retrospective analysis of 334 clinically diagnosed PSP patients conducted over 21 years demonstrated a male-to-female ratio of approximately 1.6:1, with 209 male patients (62.2%) and 125 female patients (37.4%)[2]. This male predominance has been reported across multiple cohort studies globally, suggesting a biological basis for the gender disparity rather than simply diagnostic bias.
The male predominance in PSP differs from other neurodegenerative conditions. For example, Alzheimer's disease shows a female predominance, particularly in later age groups, while Parkinson's disease exhibits a slight male excess. The 1.6:1 ratio in PSP places it closer to Parkinson's disease in terms of gender distribution, which may reflect shared underlying mechanisms related to testosterone-mediated neuroprotection or vulnerability.
Incidence rates for PSP are estimated at approximately 1-2 per 100,000 person-years in the general population over age 50, with considerable geographic variation. Studies from Europe, North America, and Asia have generally confirmed the male predominance, though the magnitude of the difference varies by population. Some Asian studies have reported a more balanced sex ratio, suggesting potential environmental or genetic modifiers of gender-based risk.
Research indicates that male PSP patients tend to experience older age at disease onset compared to female patients. Additionally, male patients often present with a [@ye2025]longer duration of illness at the time of initial neurological assessment[2]. This delayed presentation in males may relate to the higher threshold for help-seeking behavior observed in men, or alternatively, could reflect a more insidious disease onset that is recognized later by patients and caregivers.
Female patients, on average, develop PSP approximately 2-3 years earlier than males. This earlier onset in women has implications for disease duration, as women may live with PSP for longer periods, potentially accumulating greater disability before death. The earlier onset in women, combined with faster progression, creates a particularly vulnerable population requiring targeted interventions.
Despite the epidemiological differences, studies have largely failed to identify significant gender-based differences in motor skills, overall disease severity, or daily living abilities in PSP patients. A large multicenter retrospective analysis of 191 male and 157 female PSP patients in Germany found no significant differences in motor function between genders[1]. However, when examining specific motor features, meaningful differences emerge that may have clinical relevance for diagnosis and management.
Specific motor phenotypes may differ between sexes:
One of the most consistent and clinically significant gender differences identified in PSP is the higher prevalence of apathy among male patients. A 2025 multicenter retrospective study of 348 PSP patients (191 male, 157 female) found that male patients exhibited significantly higher apathy scores compared to female patients[1]. This finding aligns with observations in other neurological diseases where male patients consistently demonstrate higher rates of apathy, including Parkinson's disease, Alzheimer's disease, and traumatic brain injury.
The neurobiological basis for male susceptibility to apathy in PSP likely involves multiple factors:
Gender differences in cognitive presentation have important implications for clinical management and prognosis:
A critical finding from clinical trials is that female PSP patients experience significantly faster disease progression compared to males. In the davunetide clinical trial, females showed significantly faster deterioration on the PSP Rating Scale (PSPRS) and the Schwab and England Activities of Daily Living (SEADL) scale, with differences becoming apparent as early as trial week 13[3].
One of the most striking examples of gender-based treatment differences in PSP comes from the davunetide clinical trial. This 52-week trial involving over 200 patients revealed dramatic sex-dependent drug efficacy that has reshaped approaches to PSP therapeutic development[3]. The study, initially interpreted as a negative trial when analyzing the total population, became landmark research after post-hoc analysis revealed striking sex-specific effects.
Female-Specific Benefits:
Beyond davunetide, other therapeutic approaches may demonstrate gender-specific effects in PSP:
The gender differences in treatment response highlight the importance of:
Baseline neuroimaging differences between sexes have been documented in PSP:
Research on caregiver burden in PSP reveals that the gender of the patient does not significantly affect caregiver burden. Studies found that patient gender (whether male or female) showed no significant effect on caregiver burden (delta r² < 0.01, NS)[4].
However, caregiver gender does matter:
Caregiver burden in PSP follows a predictable pattern:
While direct research on sex hormone involvement in PSP remains limited, evidence from related tauopathies and neurodegenerative diseases provides valuable context for understanding the observed gender differences. Sex hormones exert profound effects on brain development, neuronal survival, and cognitive function, making them plausible modifiers of neurodegeneration in PSP.
Estrogen has demonstrated neuroprotective effects in various neurodegenerative conditions, including Alzheimer's disease and Parkinson's disease. The faster disease progression observed in female PSP patients, particularly post-menopause, suggests potential hormone-related protective mechanisms that warrant investigation[4]. Estrogen exerts multiple protective effects in the brain:
The higher prevalence of apathy in male PSP patients may be related to testosterone levels, as testosterone deficiency has been associated with apathy and reduced motivation in other neurological conditions. Beyond its well-known effects on motivation and reward processing, testosterone influences:
Research on related frontotemporal dementias has explored progesterone modulation of [tau pathology](/mechanisms/tau-pathology-pathway) and [TDP-43](/mechanisms/tdp-43-proteinopathy) levels[5], though specific PSP-focused studies are lacking. Progesterone's effects in the brain include:
While not a sex hormone per se, melatonin shows gender-dependent patterns and has been studied in PSP:
The emerging understanding of hormone involvement in PSP suggests several clinical considerations:
The documented gender differences have significant implications for clinical trial design:
Key areas requiring further investigation include:
Significant gender differences exist in PSP regarding clinical presentation, disease progression, treatment response, and caregiver impact. Male patients exhibit higher rates of apathy, while female patients demonstrate faster disease progression and specific benefits from certain therapies. These differences underscore the importance of personalized approaches to PSP management and the critical role of sex-specific analysis in both research and clinical practice.
The recognition of gender differences in PSP represents a paradigm shift toward precision medicine in this devastating disease. The dramatic sex-specific effects observed with davunetide demonstrate that treatments may have vastly different efficacy depending on patient sex, and that pooling data across sexes may obscure real therapeutic benefits. As the field moves forward, sex-stratified analysis should become standard in all PSP clinical trials, and clinicians should consider gender as a factor in treatment planning and prognostic counseling.
Future research priorities include: elucidating the biological mechanisms underlying the male apathy phenotype, investigating hormone replacement therapy as a potential disease-modifying strategy, developing sex-specific biomarker panels for diagnosis and prognosis, and identifying genetic factors that may explain the observed gender differences in PSP incidence and progression. The integration of sex-based considerations into PSP research and clinical care represents an important step toward more effective, personalized treatments for this underserved patient population.